Nonfullerene-based organic solar cells(NFOSCs)have received great interest recently due to their higher performance and greater potential compared with fullerene-based solar cells[1].Power conversion efficiencies(PCEs...Nonfullerene-based organic solar cells(NFOSCs)have received great interest recently due to their higher performance and greater potential compared with fullerene-based solar cells[1].Power conversion efficiencies(PCEs)over 13% have been realized in single-junction NFOSCs[2].Compared with traditional fullerene acceptors,the greatest advantage of nonfullerene acceptors is their stronger light-harvesting capability in the visible and展开更多
Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight,flexibility and roll-to-roll fabrication.Nowadays,18%power conversion efficiency has been achieved in the sta...Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight,flexibility and roll-to-roll fabrication.Nowadays,18%power conversion efficiency has been achieved in the state-of-the-art organic solar cells.The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies,and the deep understanding on film morphology,molecular packing and device physics.Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance.The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors.In this review,we focus on those star materials and milestone work,and introduce the molecular structure evolution of key materials.These key materials include homopolymer donors,D-A copolymer donors,A-D-A small molecular donors,fullerene acceptors and nonfullerene acceptors.At last,we outlook the challenges and very important directions in key materials development.展开更多
Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells(PSCs). A power conversion efficiency(PCE) of 17.22% is achieved in the optimized ternary PSCs with10 wt% MF1 ...Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells(PSCs). A power conversion efficiency(PCE) of 17.22% is achieved in the optimized ternary PSCs with10 wt% MF1 in acceptors. The over 8% PCE improvement by employing ternary strategy is attributed to the simultaneously increased JSCof 25.68 mA cm^-2, VOCof 0.853 V and FF of 78.61% compared with Y6 based binary PSCs. The good compatibility of MF1 and Y6 can be confirmed from Raman mapping, contact angle,cyclic voltammetry and morphology, which is the prerequisite to form alloy-like state. Electron mobility in ternary active layers strongly depends on MF1 content in acceptors due to the different lowest unoccupied molecular orbital(LUMO) levels of Y6 and MF1, which can well explain the wave-like varied FF of ternary PSCs. The third-party certified PCE of 16.8% should be one of the highest values for single bulk heterojunction PSCs. This work provides sufficient references for selecting materials to achieve efficient ternary PSCs.展开更多
In recent years,power conversion efficiency(PCE)of organic solar cells(OSCs)has made significant improvement.A large number of studies were reported to achieve high PCEs through exploring new active layer materials,es...In recent years,power conversion efficiency(PCE)of organic solar cells(OSCs)has made significant improvement.A large number of studies were reported to achieve high PCEs through exploring new active layer materials,especially the high efficiency fused ring acceptors(FRAs).Compared with FRAs,another type of so-called unfused-ring acceptors(UFAs),possessing some advantages such as simple synthesis and low cost,have attracted a lot of attention.Herein,a new UFA BTzO-4F,incorporating with a benzotriazole moiety and S···O intramolecular noncovalent interactions,has been successfully synthesized.The photovoltaic device based on PBDB-T:BTzO-4F achieved a record PCE of 13.8%for UFAs,which indicates that introducing the benzotriazole moiety is an effective strategy for high quality acceptors.Thus,these findings of this work demonstrate the great potential of UFAs for high performance OSCs.展开更多
The emergence of non-fullerene acceptors(NFA) offers a promising opportunity to develop high-performance donor/acceptor pairs with high power conversion efficiency,as NFAs offer tunable energy levels,broad absorption ...The emergence of non-fullerene acceptors(NFA) offers a promising opportunity to develop high-performance donor/acceptor pairs with high power conversion efficiency,as NFAs offer tunable energy levels,broad absorption and suitable aggregation property.In order to enhance light-harvesting capability of active layers,we choose a wide bandgap polymer PTQ10 as the donor to blend with a narrow bandgap NFAY6 as the acceptor.In comparison with PTQ10:IDIC blend,~130 nm red-shifted absorption spectrum is observed in the PTQ10:Y6 blend,which potentially enhance the short-circuit current density(Jsc) for the PSCs.In addition,the optimal PTQ10:Y6 blend shows higher photoluminescence quenching efficiency and more efficient charge separation,higher charge mobilities,as well as weaker bimolecular recombination over the PTQ10:IDIC blend,which leads to an outstanding power conversion efficiency(PCE) of 16.53%,with a notable Jsc of 26.65 mA cm^-2 and fill factor(FF) of 0.751.展开更多
By simplifying the r-bridge unit,a nonfused ring electron acceptor(NFREA)BM-2F was designed and synthesized with several high-yield steps.The specific molecular structure features of BM-2F are planar molecular backbon...By simplifying the r-bridge unit,a nonfused ring electron acceptor(NFREA)BM-2F was designed and synthesized with several high-yield steps.The specific molecular structure features of BM-2F are planar molecular backbone and out-of-plane side chain,which is favorable for charge transport and can suppress the over-aggregation.BM-2F based neat and blend films display obvious face-on molecular orientation.Specially,D18:BM-2F based blend film can form good bicontinuous interpenetrating network.More excitingly,a power conversion efficiency of 16.15%was achieved with D18:BM-2F based photovoltaic devices,which is the highest one based on NFREAs.Our researches manifest that NFREA is a promising direction for low-cost and high-performance organic solar cells.展开更多
The emergence of Y6-type nonfullerene acceptors has greatly enhanced the power conversion efficiency(PCE)of organic solar cells(OSCs).However,which structural feature is responsible for the excellent photovoltaic perf...The emergence of Y6-type nonfullerene acceptors has greatly enhanced the power conversion efficiency(PCE)of organic solar cells(OSCs).However,which structural feature is responsible for the excellent photovoltaic performance is still under debate.In this study,two Y6-like acceptors BDOTP-1 and BDOTP-2 were designed.Different from previous Y6-type acceptors featuring an A–D–Aʹ–D–A structure,BDOTP-1,and BDOTP-2 have no electron-deficient Aʹfragment in the core unit.Instead,there is an electron-rich dibenzodioxine fragment in the core.Although this modification leads to a marked change in the molecular dipole moment,electrostatic potential,frontier orbitals,and energy levels,BDOTP acceptors retain similar three-dimensional packing capability as Y6-type acceptors due to the similar banana-shaped molecular configuration.BDOTP acceptors show good performance in OSCs.High PCEs of up to 18.51%(certified 17.9%)are achieved.This study suggests that the banana-shaped configuration instead of the A–D–Aʹ–D–A structure is likely to be the determining factor in realizing high photovoltaic performance.展开更多
Over the past few years,the development of nonfullerene acceptors(NFAs)has become a prominent focus in both organic and perovskite solar cell(OSCs and PSCs,respectively)research fields.In this context,porphyrinoids,co...Over the past few years,the development of nonfullerene acceptors(NFAs)has become a prominent focus in both organic and perovskite solar cell(OSCs and PSCs,respectively)research fields.In this context,porphyrinoids,compounds structurally related to porphyrins,have emerged as promising solar cell candidates.In contrast to the widely used fullerene acceptors,porphyrinoids exhibit strong,broad absorption properties across the UV–vis/NIR spectrum,which can be easily tuned through chemical modifications.Furthermore,they can be prepared and derivatized using cost-effective and straightforward methodologies,allowing for convenient adjustments in thin-film morphology,processability,supramolecular organization,and energy levels.Additionally,these compounds offer higher thermal and photochemical stability,resulting in longer device lifetimes compared to their fullerene-based counterparts.In this review,we outline the utilization of porphyrinoids as NFAs in OSCs and PSCs,discussing essential aspects such as design guidelines,molecular properties,and device configuration.Our goal is to inspire and further promote the development of n-type porphyrinoids,which have not yet fully unleashed their potential.展开更多
This study attempts to develop a reproducible thin-film formation technique called vacuum-free(VF)lamination,which transfers thin films using elastomeric polymer-based laminating mediators.Precisely,by controlling the...This study attempts to develop a reproducible thin-film formation technique called vacuum-free(VF)lamination,which transfers thin films using elastomeric polymer-based laminating mediators.Precisely,by controlling the interface characteristics of the mediator based on the work of adhesion,VF lamination is successfully performed for various thicknesses(from 20 to 240 nm)of a conjugated photoactive material composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-bʹ]dithiophene))-alt-(5,5-(1ʹ,3ʹ-di-2-thienyl-5ʹ,7ʹ-bis(2-ethylhexyl)benzo[1ʹ,2ʹ-c:4ʹ,5ʹ-cʹ]dithiophene-4,8-dione)](a polymer donor)and 2,2ʹ-((2Z,2ʹZ)-((12,13-bis(2-butyloctyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2ʹʹ,3ʹʹ:4ʹ,5ʹ]thieno[2ʹ,3ʹ:4,5]pyrrolo[3,2-g]thieno[2ʹ,3ʹ:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(a nonfullerene acceptor).Interestingly,the organic photovoltaic and photodetecting applications,prepared by the VF lamination process,showed superior performance compared to those of devices prepared by conventional spin-coating.This is due to the overturned surface morphology,which led to enhanced charge transport ability and blocking of the externally injected charge.Thus,the reproducible VF lamination process,exploiting an adhesion-based elastomeric polymer mediator,is a promising thin-film formation technique for developing efficient next-generation organic optoelectronic materials consistent with the solution process.展开更多
Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at th...Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at the electron donor-acceptor interface are investigated.The film morphology exhibits notable variations,significantly depending on the layer to which 1,8-diiodooctane (DIO) was applied.Grazing incidence wide-angle X-ray scattering analysis reveals distinctly separated donor/acceptor phases and vertical crystallinity details in SD films.Time-of-flight secondary ion mass spectrometry analysis is employed to obtain component distributions in diverse vertical phase structures of SD films depending on additive control.In addition,nanosecond transient absorption spectroscopy shows that DIO control significantly affects the dynamics of separated charges in SD films.In SD OPVs,DIO appears to act through distinct mechanisms with minimal restriction,depending on the applied layer.This study emphasizes the significance of morphological optimization in improving device performance and underscores the importance of independent additive control in the advancement of OPV technology.展开更多
Theπ-πinteraction is acknowledged as the predominant factor to determine the molecular packing in organic photovoltaic materials,while other non-covalent intermolecular interactions especially theσ-πhyperconjugati...Theπ-πinteraction is acknowledged as the predominant factor to determine the molecular packing in organic photovoltaic materials,while other non-covalent intermolecular interactions especially theσ-πhyperconjugation are often ignored.Herein,a perylene diimide(PDI)derivative named FIDT-PDI is designed and synthesized to shed light into the effect of hyperconjugation on the molecular packing and further the photovoltaic performance.Dynamic NMR and 2D NOE NMR demonstrate the formation of intermolecularσ-πhyperconjugation between the C—H bond of the PDI moiety in one molecule and the phenyl sidechain in another molecule of FIDT-PDI.Benefiting from theσ-πhyperconjugation,FIDT-PDI with twisted backbone reversely exhibits more ordered packing and stronger crystallinity compared with another PDI derivative FIDTT-PDI which has better planarity,consequently achieving superior PCE and higher carrier mobility.This contribution is the first paradigm to unravel the structure-property relationship betweenσ-πhyper-conjugation of conjugated materials and corresponding photovoltaic performance.展开更多
Recently,solution-processed organic solar cells combining small-molecule donor and nonfullerene acceptor have achieved breakthrough results with the certified efficiency over 15%.These impressive progresses are driven...Recently,solution-processed organic solar cells combining small-molecule donor and nonfullerene acceptor have achieved breakthrough results with the certified efficiency over 15%.These impressive progresses are driven by the concerted efforts of modifying the donor and acceptor materials and optimizing the morphology.Considering the defined chemical structures and easily tuned properties of small-molecule materials,it is of great necessity and importance to pay more attentions on the topic of all-small molecule organic solar cells.Here,we summarize the recent progress of all-small molecule organic solar cells from the prospect of materials'evolutions and expect to provide some hints for its future developments.The involved small-molecule donors including oligothiophene-,benzodithiophene-,naphthodithiophene-,and porphyrin-based materials are discussed to illustrate the relationship of chemical structures,properties,and device performance.Then,the small-molecule nonfullerene acceptors in all-small molecules organic solar cells are discussed to highlight their vital role.Finally,we will present the challenges and future of this research area.展开更多
Nonfullerene acceptors(NFAs),which usually possess symmetric skeletons,have drawn great attention in recent years due to their pronounced advantages over the fullerene counterparts.Moreover,breaking the symmetry of NF...Nonfullerene acceptors(NFAs),which usually possess symmetric skeletons,have drawn great attention in recent years due to their pronounced advantages over the fullerene counterparts.Moreover,breaking the symmetry of NFAs could fine tune the molecular dipole,solubility,energy level,intermolecular interaction,molecular packing,crystallinity,etc.,and give rise to improved photovoltaic performance.Currently,there are three main strategies for the design of asymmetric NFAs.This review highlights the recent advances of high-performance asymmetric NFAs and briefly outlooks the materials exploration for the future.展开更多
The polymer/small-molecule electron donor and nonfullerene organic electron acceptor are of structural similarity with both donor and acceptor molecules consisting of polycyclic fused-ring backbone and being decorated...The polymer/small-molecule electron donor and nonfullerene organic electron acceptor are of structural similarity with both donor and acceptor molecules consisting of polycyclic fused-ring backbone and being decorated with alkyl-chains.In this study,we report that the introduction of binary fullerenes(C_(60)-/C_(70)-PCBM and C_(60)-/C_(70)-ICBA)into a nonfullerene binary system PBDB-T:ITIC reduces the polymer-nonfullerene acceptor intermixing,obtaining higher crystallinity with(100)crystal coherence length from 28 to 29–33 nm for the ITIC,and from 14 to 20–24 nm for the PBDB-T,and improved electron and hole mobilities both.Unprecedentedly,such a protocol reduces the ITIC optical band gap from 1.59 to 1.55 eV.As consequences,higher short-circuit current-density(17.8–18.4 vs.15.8 m A/cm^2),open-circuit voltage(0.92 vs.0.90 V)and fill-factor(0.72–0.73 vs.0.68)are simultaneously obtained,which ultimately afford higher efficient quaternary polymer solar cells with power conversion efficiencies(PCEs)up to 12.0%–12.8%comparing to the host binary device with 9.9%efficiency.For the polymer,ITIC,and ICBA/PCBM ternary blends,11%PCEs were recorded.The use of PCBM leads to larger red-shifting in thin film absorption and external quantum efficiency(EQE)response.Such effect is more pronounced when ICBA:PCBM mixture is used.These results indicate the size and shape of C_(60)and C_(70)as well as the substituent position of the second indene unit on C_(60)-/C_(70)-ICBA affect not only the blend morphology but also the electronic coupling in BHJ mixtures:the quaternary device performance increased in sequences of C_(70)-PCBM:C_(70)-ICBA→C_(70)-PCBM:C_(60)-ICBA→C_(60)-PCBM:C_(70)-ICBA→C_(60)-PCBM:C_(60)-ICBA.The resonant soft X-ray scattering(RSoXS)data indicated the most refined phase separation in the C_(60)-PCBM:C_(60)-ICBA based blend,corresponding to its best device function among the quaternary devices.These results indicate that the using of binary fullerenes as the acceptor additives allows for tuning nonfull展开更多
Recently, the fused-ring based low band gap （LBG） small molecule acceptors （SMAs） have emerged as efficient nonfullerene acceptors. So far, these LBG SMAs are mainly designed with IC （2-methylene-（3- （1,1 -dicy...Recently, the fused-ring based low band gap （LBG） small molecule acceptors （SMAs） have emerged as efficient nonfullerene acceptors. So far, these LBG SMAs are mainly designed with IC （2-methylene-（3- （1,1 -dicyanomethylene）indanone）） or its analogs, the benzo-type electron-accepting （A） units. Compared to benzene, thiophene is less aromatic and thus the thiophene-involving semiconducting molecule has more quinoidal character, which effectively reduces the energy gap between the highest occupied molecular orbit （HOMO） and the lowest unoccupied molecular orbit （LUMO）. Herein, we show that replacing the IC units in ITIC with the CT （cyclopenta[c]thiophen-4-one-5-methylene-6-（1,1-dicyano- methylene））, a thiophene-fused A unit, the quinoidal character is enhanced from 0.0353 on ITIC to 0.0349 on ITCT, the CT-ended SMA. The increase in the quinoidal character reduces the optical band gap and enhances the near IR absorptivity. When blended with the wide band gap （WBG） polymer donor, PBDB-T, an average power conversion efficiency of 10.99% is obtained with a short-circuit current-density （Jso） of 17.88 mA/cm2 and a fill-factor （FF） of 0.723. For comparisons, theJsc is of 16.92 mA/cm2, FF is of 0.655 and PCE is of 9.94% obtained from the ITIC：PBDB-T device. This case indicates that the replacement of the benzene ring on the IC unit with a more polarizable five-member ring such as thiophene is an effective way to enhance the absorption of the near IR solar photons towards designing high-performance nonfullerene polymer solar cells.展开更多
Synergistically achieving stability,cost,and efficiency is crucial for the commercialization of organic solar cells(OSCs).Despite the rapid development of 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malo nonitriletypenon ...Synergistically achieving stability,cost,and efficiency is crucial for the commercialization of organic solar cells(OSCs).Despite the rapid development of 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malo nonitriletypenon fullerene acceptors(NFAs),they areinherently unstable due to the vulnerable exocyclic double bond and possess high synthesis complexity(SC).Based on the“all-fused-ring electron acceptor(AFAR)”concept,we report two new near-infrared NFAs,F11 and F13,featuring all fused dodecacyclic rings.By developing a whole set of synthetic procedures,F11 and F13 can be conveniently prepared at a 10 g scale within a notably short period,displaying both the low SC and the lowest costs among reported NFAs,even comparable to the classical photovoltaic material,P3HT.In comparison with the one-dimensional stacking of ITYM(ITYM=2,2′-(7,7,15,15-tetrahexyl-7,15-dihydro-s-indaceno[1,2-b:5,6-b′]diindeno[1,2-d]thiophene-2,10(2H)-diylidene)dimalononitrile),the first AFRA,and mixed J-and H-aggregations in Y6,F-acceptors show a compact honeycomb-type three-dimensional stacking with exclusive J-aggregations,favoring multichannel charge transport.By matching a medium-bandgap polymer donor,F13 delivers greater than 13%power conversion efficiencies,which is the highest performance among non-INCN acceptors,and shows device stability superior to the typical ITIC-and Y6-based OSCs as evidenced by the negligible burn-in losses.This work presents a first and successful example of NFAs achieving an optimal efficiency-cost-stability balance in OSCs.展开更多
In this study,wide bandgap(WBG)two-dimensional(2D)copolymer donors(DZ1,DZ2,and DZ3)based on benzodithiophene(BDT)on alkoxyphenyl conjugated side chains without and with different amounts of chlorine atoms and difluoro...In this study,wide bandgap(WBG)two-dimensional(2D)copolymer donors(DZ1,DZ2,and DZ3)based on benzodithiophene(BDT)on alkoxyphenyl conjugated side chains without and with different amounts of chlorine atoms and difluorobenzotriazole(FBTZ)are designed and synthesized successfully for efficient non-fullerene polymer solar cells(PSCs).Three polymer donors DZ1,DZ2,and DZ3 display similar absorption spectra at 300-700 nm range with optional band-gap(Egopt)of 1.84,1.92,and 1.97 eV,respectively.Compared with reported DZ1 without chlorine substitution,it is found that introducing chlorine atoms into the meta-position of the alkoxyphenyl group affords polymer possessing a deeper the highest occupied molecular orbital(HOMO)energy level,which can increase open circuit voltage(Voc)of PSCs,as well as improve hole mobility.Non-fullerene bulk heterojunction PSCs based on DZ2:MelC demonstrate a relatively high power conversion efficiency(PCE)of 10.22%with a Voc of 0.88 V,a short-circuit current density(Jsc)of 17.62 mA/cm^2,and a fill factor(FF)of 68%,compared with PSCs based on DZ1:MelC(a PCE of 8.26%)and DZ3:MelC(a PCE of 6.28%).The results imply that adjusting chlorine atom amount on alkoxyphenyl side chains based on BDT polymer donors is a promising approach of synthesizing electron-rich building block for high performance of PSCs.展开更多
High-performance donor-acceptor electron acceptors containing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile(INCN)-type terminals are labile toward photooxidation and basic conditions,and new molecular designs ...High-performance donor-acceptor electron acceptors containing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile(INCN)-type terminals are labile toward photooxidation and basic conditions,and new molecular designs toward electron acceptors that can achieve both high power conversion efficiencies and high stability are urgently needed.By replacing the central benzene ring in the classical ladder-type n-type semiconductor,2,2′-(indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile,with the electron-rich 4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene,we report herein the design of 2,2′-(7,7,15,15-tetrahexyl-7,15-dihydro-sindaceno[1,2-b:5,6-b′]diindeno[1,2-d]thiophene-2,10(2H)-diylidene)dimalononitrile(ITYM),a new type of all-fused-ring electron acceptor(AFRA).A threestep reaction including a key Pd-catalyzed double C-H activation/intramolecular cyclization is established for the efficient synthesis of such type of electron acceptors.ITYM is confirmed by singlecrystal X-ray analysis,which shows a planar nonacyclic structure with strongπ-πstacking.Compared with the classical carbon-bridged INCN-type acceptors,ITYM exhibits extraordinary stability with very promising performance.The AFRA concept opens a new avenue toward high-efficiency and-stability organic photovoltaics(OPVs).展开更多
Asymmetric nonfullerene acceptors(NFAs)possess larger dipole moments and stronger intermolecular bonding energy than their symmetric counterparts thereby making them promising candidates for high-performance polymer s...Asymmetric nonfullerene acceptors(NFAs)possess larger dipole moments and stronger intermolecular bonding energy than their symmetric counterparts thereby making them promising candidates for high-performance polymer solar cells(PSCs).Herein,we report twoefficient acceptor–donor–acceptor(A–D–A)type NFAs(M14 and M18)with asymmetric side chains that show enhanced intermolecular interactions compared with their corresponding counterparts(M17 and M19)based on symmetric side chains.Furthermore,M14 and M18 exhibit elevated lowest unoccupiedmolecular orbitals and smallerπ–πstacking distances in comparison with M17 and M19,respectively.In combination with the benchmark polymer donor of PM6,the PM6:M14 blend affords superior charge transport properties,and more importantly,an increased power conversion efficiency(PCE)of 15.49%in comparison with the M17-based counterpart(13.01%PCE).Similarly,the asymmetric M18-based blend also shows a higher PCE of 13.00%than the M19-based blend(11.55%).Through further interface engineering,the bestperforming M14-based device delivers an enhanced PCE of 16.46%,which represents a record value among all asymmetric A–D–A type NFAs.Our results provide new insights into the design of asymmetric NFAs with enhanced intermolecular interactions for highperformance PSCs.展开更多
Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was c...Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized previously.However,the driving force that leads to this reduction was not clearly understood.In this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ composites.We demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination process.The driving force for this deactivation was determined to be the improved interchain hole delocalization between the polymers.An enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)spectroscopy.In particular,increased splitting between the polaron PIA bands was noted.Moreover,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.展开更多
基金supported by the National Natural Science Foundation of China (U1401244, 21374025,21372053,21572041,and 51503050)the National Key Research and Development Program of China (2017YFA0206600)+2 种基金the State Key Laboratory of Luminescent Materials and Devices(2016-skllmd-05)the Youth Association for Promoting Innovation(CAS)the U.S.Office of Naval Research(N00014-15-1-2244)for financial support
文摘Nonfullerene-based organic solar cells(NFOSCs)have received great interest recently due to their higher performance and greater potential compared with fullerene-based solar cells[1].Power conversion efficiencies(PCEs)over 13% have been realized in single-junction NFOSCs[2].Compared with traditional fullerene acceptors,the greatest advantage of nonfullerene acceptors is their stronger light-harvesting capability in the visible and
基金supported by the National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)。
文摘Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight,flexibility and roll-to-roll fabrication.Nowadays,18%power conversion efficiency has been achieved in the state-of-the-art organic solar cells.The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies,and the deep understanding on film morphology,molecular packing and device physics.Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance.The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors.In this review,we focus on those star materials and milestone work,and introduce the molecular structure evolution of key materials.These key materials include homopolymer donors,D-A copolymer donors,A-D-A small molecular donors,fullerene acceptors and nonfullerene acceptors.At last,we outlook the challenges and very important directions in key materials development.
基金This work was supported by the National Natural Science Foundation of China(61805009,61675017,61975006)China Postdoctoral Science Foundation(2018M641170)+1 种基金Beijing Natural Science Foundation(4192049)The authors gratefully acknowledge the assistance of the Shanghai Synchrotron Radiation Facility(beamline BL16B1)for GWAIXS and GISAXS measurements.
文摘Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells(PSCs). A power conversion efficiency(PCE) of 17.22% is achieved in the optimized ternary PSCs with10 wt% MF1 in acceptors. The over 8% PCE improvement by employing ternary strategy is attributed to the simultaneously increased JSCof 25.68 mA cm^-2, VOCof 0.853 V and FF of 78.61% compared with Y6 based binary PSCs. The good compatibility of MF1 and Y6 can be confirmed from Raman mapping, contact angle,cyclic voltammetry and morphology, which is the prerequisite to form alloy-like state. Electron mobility in ternary active layers strongly depends on MF1 content in acceptors due to the different lowest unoccupied molecular orbital(LUMO) levels of Y6 and MF1, which can well explain the wave-like varied FF of ternary PSCs. The third-party certified PCE of 16.8% should be one of the highest values for single bulk heterojunction PSCs. This work provides sufficient references for selecting materials to achieve efficient ternary PSCs.
基金the National Natural Science Foundation of China(21774130,51925306)the National Key R&D Program of China(2018FYA 0305800)+4 种基金the Key Research Program of Frontier Sciences,CAS(QYZDB-SSW-JSC046)Key Research Program of the Chinese Academy of Sciences(XDPB08-2)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB28000000)the International Partnership Program of Chinese Academy of Sciences(211211KYSB20170014)China Postdoctoral Science Foundation(2020M670425)。
文摘In recent years,power conversion efficiency(PCE)of organic solar cells(OSCs)has made significant improvement.A large number of studies were reported to achieve high PCEs through exploring new active layer materials,especially the high efficiency fused ring acceptors(FRAs).Compared with FRAs,another type of so-called unfused-ring acceptors(UFAs),possessing some advantages such as simple synthesis and low cost,have attracted a lot of attention.Herein,a new UFA BTzO-4F,incorporating with a benzotriazole moiety and S···O intramolecular noncovalent interactions,has been successfully synthesized.The photovoltaic device based on PBDB-T:BTzO-4F achieved a record PCE of 13.8%for UFAs,which indicates that introducing the benzotriazole moiety is an effective strategy for high quality acceptors.Thus,these findings of this work demonstrate the great potential of UFAs for high performance OSCs.
基金supported by the National Natural Science Foundation of China(51873140,51603136,91633301)
文摘The emergence of non-fullerene acceptors(NFA) offers a promising opportunity to develop high-performance donor/acceptor pairs with high power conversion efficiency,as NFAs offer tunable energy levels,broad absorption and suitable aggregation property.In order to enhance light-harvesting capability of active layers,we choose a wide bandgap polymer PTQ10 as the donor to blend with a narrow bandgap NFAY6 as the acceptor.In comparison with PTQ10:IDIC blend,~130 nm red-shifted absorption spectrum is observed in the PTQ10:Y6 blend,which potentially enhance the short-circuit current density(Jsc) for the PSCs.In addition,the optimal PTQ10:Y6 blend shows higher photoluminescence quenching efficiency and more efficient charge separation,higher charge mobilities,as well as weaker bimolecular recombination over the PTQ10:IDIC blend,which leads to an outstanding power conversion efficiency(PCE) of 16.53%,with a notable Jsc of 26.65 mA cm^-2 and fill factor(FF) of 0.751.
基金This research was made possible thanks to the financial support from the National Natural Science Foundation of China(51933001,52173174,22109080,21734009).
文摘By simplifying the r-bridge unit,a nonfused ring electron acceptor(NFREA)BM-2F was designed and synthesized with several high-yield steps.The specific molecular structure features of BM-2F are planar molecular backbone and out-of-plane side chain,which is favorable for charge transport and can suppress the over-aggregation.BM-2F based neat and blend films display obvious face-on molecular orientation.Specially,D18:BM-2F based blend film can form good bicontinuous interpenetrating network.More excitingly,a power conversion efficiency of 16.15%was achieved with D18:BM-2F based photovoltaic devices,which is the highest one based on NFREAs.Our researches manifest that NFREA is a promising direction for low-cost and high-performance organic solar cells.
基金the open research fund of the Songshan Lake Materials Laboratory(2021SLABFK02)the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51922032 and 21961160720).
文摘The emergence of Y6-type nonfullerene acceptors has greatly enhanced the power conversion efficiency(PCE)of organic solar cells(OSCs).However,which structural feature is responsible for the excellent photovoltaic performance is still under debate.In this study,two Y6-like acceptors BDOTP-1 and BDOTP-2 were designed.Different from previous Y6-type acceptors featuring an A–D–Aʹ–D–A structure,BDOTP-1,and BDOTP-2 have no electron-deficient Aʹfragment in the core unit.Instead,there is an electron-rich dibenzodioxine fragment in the core.Although this modification leads to a marked change in the molecular dipole moment,electrostatic potential,frontier orbitals,and energy levels,BDOTP acceptors retain similar three-dimensional packing capability as Y6-type acceptors due to the similar banana-shaped molecular configuration.BDOTP acceptors show good performance in OSCs.High PCEs of up to 18.51%(certified 17.9%)are achieved.This study suggests that the banana-shaped configuration instead of the A–D–Aʹ–D–A structure is likely to be the determining factor in realizing high photovoltaic performance.
基金T.T.acknowledges financial support from the Spanish MCIN/AEI/10.13039/501100011033(PID2020-116490GBI00,TED2021-131255B-C43)the Comunidad de Madrid and the Spanish State through the Recovery,Transformation and Resilience Plan[“Materiales Disruptivos Bidimensionales(2D)”(MAD2D-CM)(UAM1)-MRR Materiales Avanzados]+2 种基金the European Union through the Next Generation EU funds.Instituto madrileno de estudios avanzados Nanociencia acknowledges support from the“Severo Ochoa”Programme for Centres of Excellence in R&D(Ministerio de asuntos economicos y transformacion digital,Grant SEV2016-0686)T.T.also acknowledges the Alexander von Humboldt Foundation(Germany)for the A.v.Humboldt-J.C.Mutis Research Award 2023(Ref 3.3-1231125-ESP-GSA)J.L.acknowledgesMinisterio de Eduacion,Cultura y Deporte(MECD),Spain,for an F.P.U.Fellowship.
文摘Over the past few years,the development of nonfullerene acceptors(NFAs)has become a prominent focus in both organic and perovskite solar cell(OSCs and PSCs,respectively)research fields.In this context,porphyrinoids,compounds structurally related to porphyrins,have emerged as promising solar cell candidates.In contrast to the widely used fullerene acceptors,porphyrinoids exhibit strong,broad absorption properties across the UV–vis/NIR spectrum,which can be easily tuned through chemical modifications.Furthermore,they can be prepared and derivatized using cost-effective and straightforward methodologies,allowing for convenient adjustments in thin-film morphology,processability,supramolecular organization,and energy levels.Additionally,these compounds offer higher thermal and photochemical stability,resulting in longer device lifetimes compared to their fullerene-based counterparts.In this review,we outline the utilization of porphyrinoids as NFAs in OSCs and PSCs,discussing essential aspects such as design guidelines,molecular properties,and device configuration.Our goal is to inspire and further promote the development of n-type porphyrinoids,which have not yet fully unleashed their potential.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Science,ICT (MSIT) (Grant Nos.2023R1A2C2008021 and RS-2023-00217270)supported by the Technology Innovation Program (Grant No.20017439,“Development of manufacturing process technique on high-speed signal transmission line for 6G device,”and Grant No.20021915,“Development on Nanocomposite Material of Optical Film[GPa]for Foldable Devices”)funded by the Ministry of Trade,Industry&Energy (MOTIE,Korea).
文摘This study attempts to develop a reproducible thin-film formation technique called vacuum-free(VF)lamination,which transfers thin films using elastomeric polymer-based laminating mediators.Precisely,by controlling the interface characteristics of the mediator based on the work of adhesion,VF lamination is successfully performed for various thicknesses(from 20 to 240 nm)of a conjugated photoactive material composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-bʹ]dithiophene))-alt-(5,5-(1ʹ,3ʹ-di-2-thienyl-5ʹ,7ʹ-bis(2-ethylhexyl)benzo[1ʹ,2ʹ-c:4ʹ,5ʹ-cʹ]dithiophene-4,8-dione)](a polymer donor)and 2,2ʹ-((2Z,2ʹZ)-((12,13-bis(2-butyloctyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2ʹʹ,3ʹʹ:4ʹ,5ʹ]thieno[2ʹ,3ʹ:4,5]pyrrolo[3,2-g]thieno[2ʹ,3ʹ:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(a nonfullerene acceptor).Interestingly,the organic photovoltaic and photodetecting applications,prepared by the VF lamination process,showed superior performance compared to those of devices prepared by conventional spin-coating.This is due to the overturned surface morphology,which led to enhanced charge transport ability and blocking of the externally injected charge.Thus,the reproducible VF lamination process,exploiting an adhesion-based elastomeric polymer mediator,is a promising thin-film formation technique for developing efficient next-generation organic optoelectronic materials consistent with the solution process.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2023-00213920,NRF-2021R1A4A1031761).
文摘Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at the electron donor-acceptor interface are investigated.The film morphology exhibits notable variations,significantly depending on the layer to which 1,8-diiodooctane (DIO) was applied.Grazing incidence wide-angle X-ray scattering analysis reveals distinctly separated donor/acceptor phases and vertical crystallinity details in SD films.Time-of-flight secondary ion mass spectrometry analysis is employed to obtain component distributions in diverse vertical phase structures of SD films depending on additive control.In addition,nanosecond transient absorption spectroscopy shows that DIO control significantly affects the dynamics of separated charges in SD films.In SD OPVs,DIO appears to act through distinct mechanisms with minimal restriction,depending on the applied layer.This study emphasizes the significance of morphological optimization in improving device performance and underscores the importance of independent additive control in the advancement of OPV technology.
基金supported by the Natural Science Foundation of Shanghai (21ZR1435100)Shenzhen Science and Technology Innovation Commission (2021SZVUP075)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University (SL2022MS015).
文摘Theπ-πinteraction is acknowledged as the predominant factor to determine the molecular packing in organic photovoltaic materials,while other non-covalent intermolecular interactions especially theσ-πhyperconjugation are often ignored.Herein,a perylene diimide(PDI)derivative named FIDT-PDI is designed and synthesized to shed light into the effect of hyperconjugation on the molecular packing and further the photovoltaic performance.Dynamic NMR and 2D NOE NMR demonstrate the formation of intermolecularσ-πhyperconjugation between the C—H bond of the PDI moiety in one molecule and the phenyl sidechain in another molecule of FIDT-PDI.Benefiting from theσ-πhyperconjugation,FIDT-PDI with twisted backbone reversely exhibits more ordered packing and stronger crystallinity compared with another PDI derivative FIDTT-PDI which has better planarity,consequently achieving superior PCE and higher carrier mobility.This contribution is the first paradigm to unravel the structure-property relationship betweenσ-πhyper-conjugation of conjugated materials and corresponding photovoltaic performance.
基金the financial support from the Office of Naval Research(N00014-17-1-2260 and N00014-20-1-2191).
文摘Recently,solution-processed organic solar cells combining small-molecule donor and nonfullerene acceptor have achieved breakthrough results with the certified efficiency over 15%.These impressive progresses are driven by the concerted efforts of modifying the donor and acceptor materials and optimizing the morphology.Considering the defined chemical structures and easily tuned properties of small-molecule materials,it is of great necessity and importance to pay more attentions on the topic of all-small molecule organic solar cells.Here,we summarize the recent progress of all-small molecule organic solar cells from the prospect of materials'evolutions and expect to provide some hints for its future developments.The involved small-molecule donors including oligothiophene-,benzodithiophene-,naphthodithiophene-,and porphyrin-based materials are discussed to illustrate the relationship of chemical structures,properties,and device performance.Then,the small-molecule nonfullerene acceptors in all-small molecules organic solar cells are discussed to highlight their vital role.Finally,we will present the challenges and future of this research area.
基金supported by the National Natural Science Foundation of China(Nos.22075069,51933001)Natural Science Foundation of Henan Province(No.212300410002)Program sponsored by Henan Province(Nos.23ZX002,ZYQR201912163).
文摘Nonfullerene acceptors(NFAs),which usually possess symmetric skeletons,have drawn great attention in recent years due to their pronounced advantages over the fullerene counterparts.Moreover,breaking the symmetry of NFAs could fine tune the molecular dipole,solubility,energy level,intermolecular interaction,molecular packing,crystallinity,etc.,and give rise to improved photovoltaic performance.Currently,there are three main strategies for the design of asymmetric NFAs.This review highlights the recent advances of high-performance asymmetric NFAs and briefly outlooks the materials exploration for the future.
基金supported by the National Natural Science Foundation of China (91433202, 21773262, 21327805, 21521062, 91227112)Chinese Academy of Sciences (XDB12010200)+1 种基金Ministry of Science and Technology of China (2013CB933503)the US Office of Naval Research (N00014-15-1-2244)
文摘The polymer/small-molecule electron donor and nonfullerene organic electron acceptor are of structural similarity with both donor and acceptor molecules consisting of polycyclic fused-ring backbone and being decorated with alkyl-chains.In this study,we report that the introduction of binary fullerenes(C_(60)-/C_(70)-PCBM and C_(60)-/C_(70)-ICBA)into a nonfullerene binary system PBDB-T:ITIC reduces the polymer-nonfullerene acceptor intermixing,obtaining higher crystallinity with(100)crystal coherence length from 28 to 29–33 nm for the ITIC,and from 14 to 20–24 nm for the PBDB-T,and improved electron and hole mobilities both.Unprecedentedly,such a protocol reduces the ITIC optical band gap from 1.59 to 1.55 eV.As consequences,higher short-circuit current-density(17.8–18.4 vs.15.8 m A/cm^2),open-circuit voltage(0.92 vs.0.90 V)and fill-factor(0.72–0.73 vs.0.68)are simultaneously obtained,which ultimately afford higher efficient quaternary polymer solar cells with power conversion efficiencies(PCEs)up to 12.0%–12.8%comparing to the host binary device with 9.9%efficiency.For the polymer,ITIC,and ICBA/PCBM ternary blends,11%PCEs were recorded.The use of PCBM leads to larger red-shifting in thin film absorption and external quantum efficiency(EQE)response.Such effect is more pronounced when ICBA:PCBM mixture is used.These results indicate the size and shape of C_(60)and C_(70)as well as the substituent position of the second indene unit on C_(60)-/C_(70)-ICBA affect not only the blend morphology but also the electronic coupling in BHJ mixtures:the quaternary device performance increased in sequences of C_(70)-PCBM:C_(70)-ICBA→C_(70)-PCBM:C_(60)-ICBA→C_(60)-PCBM:C_(70)-ICBA→C_(60)-PCBM:C_(60)-ICBA.The resonant soft X-ray scattering(RSoXS)data indicated the most refined phase separation in the C_(60)-PCBM:C_(60)-ICBA based blend,corresponding to its best device function among the quaternary devices.These results indicate that the using of binary fullerenes as the acceptor additives allows for tuning nonfull
基金the financial support from the National Natural Science Foundation of China(NSFC, Nos. 91433202, 91227112 and 21221002)Chinese Academy of Sciences(CAS, No. XDB12010200)
文摘Recently, the fused-ring based low band gap （LBG） small molecule acceptors （SMAs） have emerged as efficient nonfullerene acceptors. So far, these LBG SMAs are mainly designed with IC （2-methylene-（3- （1,1 -dicyanomethylene）indanone）） or its analogs, the benzo-type electron-accepting （A） units. Compared to benzene, thiophene is less aromatic and thus the thiophene-involving semiconducting molecule has more quinoidal character, which effectively reduces the energy gap between the highest occupied molecular orbit （HOMO） and the lowest unoccupied molecular orbit （LUMO）. Herein, we show that replacing the IC units in ITIC with the CT （cyclopenta[c]thiophen-4-one-5-methylene-6-（1,1-dicyano- methylene））, a thiophene-fused A unit, the quinoidal character is enhanced from 0.0353 on ITIC to 0.0349 on ITCT, the CT-ended SMA. The increase in the quinoidal character reduces the optical band gap and enhances the near IR absorptivity. When blended with the wide band gap （WBG） polymer donor, PBDB-T, an average power conversion efficiency of 10.99% is obtained with a short-circuit current-density （Jso） of 17.88 mA/cm2 and a fill-factor （FF） of 0.723. For comparisons, theJsc is of 16.92 mA/cm2, FF is of 0.655 and PCE is of 9.94% obtained from the ITIC：PBDB-T device. This case indicates that the replacement of the benzene ring on the IC unit with a more polarizable five-member ring such as thiophene is an effective way to enhance the absorption of the near IR solar photons towards designing high-performance nonfullerene polymer solar cells.
基金The authors thank the National Key R&D Program of China(grant nos.2019YFA0705900 and 2017YFA0204701)the National Natural Science Foundation of China(grant nos.22175187,91833304,21805289,and 22171273)+1 种基金Key Research Program of the Chinese Academy of Sciences(grant no.XDPB13)Youth Innovation Promotion Association CAS(grant no.2020031)for their financial support.
文摘Synergistically achieving stability,cost,and efficiency is crucial for the commercialization of organic solar cells(OSCs).Despite the rapid development of 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malo nonitriletypenon fullerene acceptors(NFAs),they areinherently unstable due to the vulnerable exocyclic double bond and possess high synthesis complexity(SC).Based on the“all-fused-ring electron acceptor(AFAR)”concept,we report two new near-infrared NFAs,F11 and F13,featuring all fused dodecacyclic rings.By developing a whole set of synthetic procedures,F11 and F13 can be conveniently prepared at a 10 g scale within a notably short period,displaying both the low SC and the lowest costs among reported NFAs,even comparable to the classical photovoltaic material,P3HT.In comparison with the one-dimensional stacking of ITYM(ITYM=2,2′-(7,7,15,15-tetrahexyl-7,15-dihydro-s-indaceno[1,2-b:5,6-b′]diindeno[1,2-d]thiophene-2,10(2H)-diylidene)dimalononitrile),the first AFRA,and mixed J-and H-aggregations in Y6,F-acceptors show a compact honeycomb-type three-dimensional stacking with exclusive J-aggregations,favoring multichannel charge transport.By matching a medium-bandgap polymer donor,F13 delivers greater than 13%power conversion efficiencies,which is the highest performance among non-INCN acceptors,and shows device stability superior to the typical ITIC-and Y6-based OSCs as evidenced by the negligible burn-in losses.This work presents a first and successful example of NFAs achieving an optimal efficiency-cost-stability balance in OSCs.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51763017,21602150,51425304,51863012,21861025,51833004)the Shen Zhen Technology and Innovation Commission(Nos.JCYJ20170413173814007,JCYJ20170818113905024)+4 种基金the Hong Kong Research Grants Council(Research Impact Fund R6021-18,Nos.16305915,16322416,606012,16303917)Hong Kong Innovation and Technology Commission for the support through projects ITC-CNERC14SC01 and ITS/471/18,the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(No.2018R1A2A1A05077194)Wearable Platform Materials Technology Center(WMCNo.2016R1A5A1009926)funded by the National Research Foundation of Korea(NRF)Grant by the Korean Government(MSIT)the Research Project Funded by Ulsan City(No.1.200042)of UNIST(Ulsan National Institute of Science&Technology).
文摘In this study,wide bandgap(WBG)two-dimensional(2D)copolymer donors(DZ1,DZ2,and DZ3)based on benzodithiophene(BDT)on alkoxyphenyl conjugated side chains without and with different amounts of chlorine atoms and difluorobenzotriazole(FBTZ)are designed and synthesized successfully for efficient non-fullerene polymer solar cells(PSCs).Three polymer donors DZ1,DZ2,and DZ3 display similar absorption spectra at 300-700 nm range with optional band-gap(Egopt)of 1.84,1.92,and 1.97 eV,respectively.Compared with reported DZ1 without chlorine substitution,it is found that introducing chlorine atoms into the meta-position of the alkoxyphenyl group affords polymer possessing a deeper the highest occupied molecular orbital(HOMO)energy level,which can increase open circuit voltage(Voc)of PSCs,as well as improve hole mobility.Non-fullerene bulk heterojunction PSCs based on DZ2:MelC demonstrate a relatively high power conversion efficiency(PCE)of 10.22%with a Voc of 0.88 V,a short-circuit current density(Jsc)of 17.62 mA/cm^2,and a fill factor(FF)of 68%,compared with PSCs based on DZ1:MelC(a PCE of 8.26%)and DZ3:MelC(a PCE of 6.28%).The results imply that adjusting chlorine atom amount on alkoxyphenyl side chains based on BDT polymer donors is a promising approach of synthesizing electron-rich building block for high performance of PSCs.
基金The authors thank the National Key R&D Program of China(nos.2019YFA0705900 and 2017YFA0204701)the National Natural Science Foundation of China(nos.21661132006 and 91833304)for their financial support。
文摘High-performance donor-acceptor electron acceptors containing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile(INCN)-type terminals are labile toward photooxidation and basic conditions,and new molecular designs toward electron acceptors that can achieve both high power conversion efficiencies and high stability are urgently needed.By replacing the central benzene ring in the classical ladder-type n-type semiconductor,2,2′-(indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile,with the electron-rich 4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene,we report herein the design of 2,2′-(7,7,15,15-tetrahexyl-7,15-dihydro-sindaceno[1,2-b:5,6-b′]diindeno[1,2-d]thiophene-2,10(2H)-diylidene)dimalononitrile(ITYM),a new type of all-fused-ring electron acceptor(AFRA).A threestep reaction including a key Pd-catalyzed double C-H activation/intramolecular cyclization is established for the efficient synthesis of such type of electron acceptors.ITYM is confirmed by singlecrystal X-ray analysis,which shows a planar nonacyclic structure with strongπ-πstacking.Compared with the classical carbon-bridged INCN-type acceptors,ITYM exhibits extraordinary stability with very promising performance.The AFRA concept opens a new avenue toward high-efficiency and-stability organic photovoltaics(OPVs).
基金supported by the National Natural Science Foundation of China(nos.22101285,51873138,52130306,21734009,and 22075287)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)(no.QYZDB-SSW-SLH032)+2 种基金the China Postdoctoral Science Foundation(no.2021M703218)the Program of Youth Innovation Promotion Association CAS(no.2021000060)Beijing National Laboratory for Molecular Sciences(no.BNLMS201902).
文摘Asymmetric nonfullerene acceptors(NFAs)possess larger dipole moments and stronger intermolecular bonding energy than their symmetric counterparts thereby making them promising candidates for high-performance polymer solar cells(PSCs).Herein,we report twoefficient acceptor–donor–acceptor(A–D–A)type NFAs(M14 and M18)with asymmetric side chains that show enhanced intermolecular interactions compared with their corresponding counterparts(M17 and M19)based on symmetric side chains.Furthermore,M14 and M18 exhibit elevated lowest unoccupiedmolecular orbitals and smallerπ–πstacking distances in comparison with M17 and M19,respectively.In combination with the benchmark polymer donor of PM6,the PM6:M14 blend affords superior charge transport properties,and more importantly,an increased power conversion efficiency(PCE)of 15.49%in comparison with the M17-based counterpart(13.01%PCE).Similarly,the asymmetric M18-based blend also shows a higher PCE of 13.00%than the M19-based blend(11.55%).Through further interface engineering,the bestperforming M14-based device delivers an enhanced PCE of 16.46%,which represents a record value among all asymmetric A–D–A type NFAs.Our results provide new insights into the design of asymmetric NFAs with enhanced intermolecular interactions for highperformance PSCs.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(2022R1F1A1065586,2019R1A6A1A11053838)the GIST Research Institute(GRI)APRI grant funded by the GIST in 2022.
文摘Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized previously.However,the driving force that leads to this reduction was not clearly understood.In this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ composites.We demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination process.The driving force for this deactivation was determined to be the improved interchain hole delocalization between the polymers.An enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)spectroscopy.In particular,increased splitting between the polaron PIA bands was noted.Moreover,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.
