The easy oxidation and surface roughness of Cu nanowire （NW） films are the main bottlenecks for their usage in transparent conductive electrodes （TCEs）. Herein, we have developed a facile and scaled-up solution ro...The easy oxidation and surface roughness of Cu nanowire （NW） films are the main bottlenecks for their usage in transparent conductive electrodes （TCEs）. Herein, we have developed a facile and scaled-up solution route to prepare Cu NW-based TCEs by embedding Cu NWs into pre-coated smooth poly（3,4-ethylenedioxythiophene）：poly（styrenesulfonate） （PEDOT：PSS） films on poly（ethylene terephthalate） （PET） substrates. The so obtained Cu NW- PEDOT：PSS/PET films have low surface roughness （-70 nm in height）, high stability toward oxidation and good flexibility. The optimal TCEs show a typical sheet resistance of 15Ω·sq-1 at high transparency （76% at A = 550 nm） and have been used successfully to make polymer （poly（3-hexylthiophene）：phenyl-C61- butyric acid methyl ester） solar cells, giving an efficiency of 1.4%. The overall properties of Cu NW-PEDOT：PSS/PET films demonstrate their potential application as a replacement for indium tin oxide in flexible solar cells.展开更多
Field-effect transistors（FETs） of three diketopyrrolopyrroles（DPP）-based small molecules, 3,6-bis（5-phenylthiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolopyrrole-1,4-dione（PDPPP）, 3,6-bis（5-（4-fluorophenyl）th...Field-effect transistors（FETs） of three diketopyrrolopyrroles（DPP）-based small molecules, 3,6-bis（5-phenylthiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolopyrrole-1,4-dione（PDPPP）, 3,6-bis（5-（4-fluorophenyl）thiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolo pyrrole-1,4-dione（FPDPPPF） and 3,6-bis（5-（4-n-butylphenyl）thiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolo pyrrole-1,4-dione（Bu PDPPPBu）, have been studied in this work. Well aligned crystals of the three molecules were grown from para-xylene by droplet-pinned crystallization method. FETs based on these aligned crystals exhibit a hole mobility up to0.19 cm^2 V 1s 1and electron mobility up to 0.008 cm^2 V 1s 1. The achieved hole mobility is of the same order of magnitude as reported highest hole mobility for DPP-based small molecules, but it is much lower than that of the high-performance DPP-based polymers. The relative low mobility is mainly attributed to the rough crystal surfaces with steps and, thus, non-smooth charge transport channels at the interfaces between the crystals and the dielectrics. This work has implications for understanding the low charge mobility of DPP-based small molecules.展开更多
The development of high-performance solution-processed red organic light-emitting diodes(OLEDs) remains a challenge,particularly in terms of maintaining efficiency at high luminance. Here, we designed and synthesized ...The development of high-performance solution-processed red organic light-emitting diodes(OLEDs) remains a challenge,particularly in terms of maintaining efficiency at high luminance. Here, we designed and synthesized four novel orange-red thermally activated delayed fluorescence(TADF) dendrimers that are solution-processable: 2GCz BP, 2DPACz BP, 2FBP2GCz and 2FBP2DPACz. We systematically investigated the effect of substitution position and strength of donors on the optoelectronic properties. The reverse intersystem crossing rate constant(kRISC) of the emitters having donors substituted at positions 11and 12 of the dibenzo[a,c]phenazine(BP) is more than 10-times faster than that of compounds substituted having donors substituted at positions 3 and 6. Compound 2DPACz BP, containing stronger donors than 2GCz BP, exhibits a red-shifted emission and smaller singlet-triplet energy splitting, ΔE_(ST), of 0.01 e V. The solution-processed OLED with 10 wt% 2DPACz BP doped in m CP emitted at 640 nm and showed a maximum external quantum efficiency(EQE_(max)) of 7.8%, which was effectively maintained out to a luminance of 1,000 cd m-2. Such a device's performance at relevant display luminance is among the highest for solution-processed red TADF OLEDs. The efficiency of the devices was improved significantly by using 4Cz IPN as an assistant dopant in a hyperfluorescence(HF) configuration, where the 2DPACz BP HF device shows an EQEmaxof 20.0% at λEL of 605 nm and remains high at 11.8% at a luminance of 1,000 cd m-2, which makes this device one of the highest efficiency orange-to-red HF SP-OLEDs to date.展开更多
Curvature sensing plays an important role in structural health monitoring,damage detection,real-time shape control,modification,etc.Developing curvature sensors with large measurement ranges,high sensitivity,and linea...Curvature sensing plays an important role in structural health monitoring,damage detection,real-time shape control,modification,etc.Developing curvature sensors with large measurement ranges,high sensitivity,and linearity remains a major challenge.In this study,a curvature sensor based on flexible one-dimensional photonic crystal(1D-PC)films was proposed.The flexible 1D-PC films composed of dense chalcogenide glass and water-soluble polymer materials were fabricated by solution processing.The flexible 1D-PC film curvature sensor has a wide measurement range of 33-133 m-1and a maximum sensitivity of0.26 nm/m^(-1).The shift of the transmission peak varies approximately linearly with the curvature in the entire measurement range.This kind of 1D-PC film curvature sensor provides a new idea for curvature sensing and measurement.展开更多
A solution-processed CuOx film has been successfully integrated as the hole-transporting layer（HTL） for inverted planar heterojunction perovskite solar cells（PVSCs）. The CuOx layer is fabricated by simply spin-coa...A solution-processed CuOx film has been successfully integrated as the hole-transporting layer（HTL） for inverted planar heterojunction perovskite solar cells（PVSCs）. The CuOx layer is fabricated by simply spin-coating a copper acetylacetonate（Cu（acac）2） chloroform solution onto ITO glass with high transparency in the visible range. The compact and pinhole-free perovskite film with large grain domains is grown on the CuOx film. The inverted PVSCs with the structure of ITO/CuOx/MAPbI3/PC（61）BM/ZnO/Al are fabricated and show a best PCE of 17.43% under standard AM 1.5G simulated solar irradiation with a VOCof 1.03 V, aJ（SC） of 22.42 mA cm^（-2）, and a fill factor of 0.76, which is significantly higher and more stable than that fabricated from the often used hole-transporting material PEDOT：PSS（11.98%） under the same experimental conditions. The enhanced performance is attributed to the efficient hole extraction through the CuOx layer as well as the high-quality CH3NH3PbI3 films grown on the CuOx. Our results indicate that low-cost and solution-processed CuOx film is a promising HTL for high performance PVSCs with better stability.展开更多
Covalent organic polymers(COPs)have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures.However,their layered stacks and limited solubility preclude further processing for l...Covalent organic polymers(COPs)have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures.However,their layered stacks and limited solubility preclude further processing for large-scale applications in devices,especially optoelectronic equipment.Herein,a universal strategy to adjust the electron donor–acceptor(D-A)moieties of the building blocks in COPs is proposed,achieved by in situ charge exfoliation of COP blocks into few-layer true solutions in(Lewis)acid and base media.The electron D-A moieties of the building blocks endow the COPs with the ability to accept or donate electrons,by altering the electron cloud distribution as well as the relative energy levels of the frontier molecular orbitals.The resultant soluble COPs can easily be processed into a uniform film by solution processing via the spin-coat method.The obtained COP-N achieves efficient and stable perovskite electroluminescence as a novel hole injection material on indium tin oxide,and the operating lifetime for a perovskite quantum dot light-emitting diodes device exceeds that of a poly(ethylene dioxythiophene):polystyrene sulphonate counterpart.This straightforward electronic regulation strategy provides a new avenue for the rational synthesis of processable reticular molecular polymers for practical electronic devices.展开更多
Nickel oxide(NiOx),a p-type oxide semiconductor,has gained significant attention due to its versatile and tunable properties.It has become one of the critical materials in wide range of electronics applications,includ...Nickel oxide(NiOx),a p-type oxide semiconductor,has gained significant attention due to its versatile and tunable properties.It has become one of the critical materials in wide range of electronics applications,including resistive switching random access memory devices and highly sensitive and selective sensor applications.In addition,the wide band gap and high work function,coupled with the low electron affinity,have made NiOx widely used in emerging optoelectronics and p-n heterojunctions.The properties of NiOx thin films depend strongly on the deposition method and conditions.Efficient implementation of NiOx in next-generation devices will require controllable growth and processing methods that can tailor the morphological and electronic properties of the material,but which are also compatible with flexible substrates.In this review,we link together the fundamental properties of NiOx with the chemical processing methods that have been developed to grow the material as thin films,and with its application in electronic devices.We focus solely on thin films,rather than NiOx incorporated with one-dimensional or two-dimensional materials.This review starts by discussing how the p-type nature of NiOx arises and how its stoichiometry affects its electronic and magnetic properties.We discuss the chemical deposition techniques for growing NiOx thin films,including chemical vapor deposition,atomic layer deposition,and a selection of solution processing approaches,and present examples of recent progress made in the implementation of NiOx thin films in devices,both on rigid and flexible substrates.Furthermore,we discuss the remaining challenges and limitations in the deposition of device-quality NiOx thin films with chemical growth methods.展开更多
Flexible organic field-effect transistors(OFETs)using solution-processable functionalized graphene for all the electrodes(source,drain,and gate)have been fabricated for the first time.These OFETs show performance comp...Flexible organic field-effect transistors(OFETs)using solution-processable functionalized graphene for all the electrodes(source,drain,and gate)have been fabricated for the first time.These OFETs show performance comparable to corresponding devices using Au electrodes as the source/drain electrodes on SiO2/Si substrates with Si as the gate electrode.Also,these devices demonstrate excellent flexibility without performance degradation over severe bending cycles.Furthermore,inverter circuits have been designed and fabricated using these all-graphene-electrode OFETs.Our results demonstrate that the long-sought dream for all-carbon and flexible electronics is now much closer to reality.展开更多
文摘The easy oxidation and surface roughness of Cu nanowire （NW） films are the main bottlenecks for their usage in transparent conductive electrodes （TCEs）. Herein, we have developed a facile and scaled-up solution route to prepare Cu NW-based TCEs by embedding Cu NWs into pre-coated smooth poly（3,4-ethylenedioxythiophene）：poly（styrenesulfonate） （PEDOT：PSS） films on poly（ethylene terephthalate） （PET） substrates. The so obtained Cu NW- PEDOT：PSS/PET films have low surface roughness （-70 nm in height）, high stability toward oxidation and good flexibility. The optimal TCEs show a typical sheet resistance of 15Ω·sq-1 at high transparency （76% at A = 550 nm） and have been used successfully to make polymer （poly（3-hexylthiophene）：phenyl-C61- butyric acid methyl ester） solar cells, giving an efficiency of 1.4%. The overall properties of Cu NW-PEDOT：PSS/PET films demonstrate their potential application as a replacement for indium tin oxide in flexible solar cells.
基金supported by the 973 Program (No. 2014CB643503)National Natural Science Foundation of China (Nos. 51373150, 51461165301)+1 种基金Zhejiang Province Natural Science Foundation (No. LZ13E030002)Fundamental Research Funds for the Central Universities
文摘Field-effect transistors（FETs） of three diketopyrrolopyrroles（DPP）-based small molecules, 3,6-bis（5-phenylthiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolopyrrole-1,4-dione（PDPPP）, 3,6-bis（5-（4-fluorophenyl）thiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolo pyrrole-1,4-dione（FPDPPPF） and 3,6-bis（5-（4-n-butylphenyl）thiophene-2-yl）-2,5-bis（2-ethylhexyl）pyrrolo pyrrole-1,4-dione（Bu PDPPPBu）, have been studied in this work. Well aligned crystals of the three molecules were grown from para-xylene by droplet-pinned crystallization method. FETs based on these aligned crystals exhibit a hole mobility up to0.19 cm^2 V 1s 1and electron mobility up to 0.008 cm^2 V 1s 1. The achieved hole mobility is of the same order of magnitude as reported highest hole mobility for DPP-based small molecules, but it is much lower than that of the high-performance DPP-based polymers. The relative low mobility is mainly attributed to the rough crystal surfaces with steps and, thus, non-smooth charge transport channels at the interfaces between the crystals and the dielectrics. This work has implications for understanding the low charge mobility of DPP-based small molecules.
基金the China Scholarship Council(201806890001)support from the Royal Academy of Engineering Enterprise Fellowship (EF2122-13106)EPSRC (EP/W015137/1, EP/W524505/1) for financial support。
文摘The development of high-performance solution-processed red organic light-emitting diodes(OLEDs) remains a challenge,particularly in terms of maintaining efficiency at high luminance. Here, we designed and synthesized four novel orange-red thermally activated delayed fluorescence(TADF) dendrimers that are solution-processable: 2GCz BP, 2DPACz BP, 2FBP2GCz and 2FBP2DPACz. We systematically investigated the effect of substitution position and strength of donors on the optoelectronic properties. The reverse intersystem crossing rate constant(kRISC) of the emitters having donors substituted at positions 11and 12 of the dibenzo[a,c]phenazine(BP) is more than 10-times faster than that of compounds substituted having donors substituted at positions 3 and 6. Compound 2DPACz BP, containing stronger donors than 2GCz BP, exhibits a red-shifted emission and smaller singlet-triplet energy splitting, ΔE_(ST), of 0.01 e V. The solution-processed OLED with 10 wt% 2DPACz BP doped in m CP emitted at 640 nm and showed a maximum external quantum efficiency(EQE_(max)) of 7.8%, which was effectively maintained out to a luminance of 1,000 cd m-2. Such a device's performance at relevant display luminance is among the highest for solution-processed red TADF OLEDs. The efficiency of the devices was improved significantly by using 4Cz IPN as an assistant dopant in a hyperfluorescence(HF) configuration, where the 2DPACz BP HF device shows an EQEmaxof 20.0% at λEL of 605 nm and remains high at 11.8% at a luminance of 1,000 cd m-2, which makes this device one of the highest efficiency orange-to-red HF SP-OLEDs to date.
基金supported by the National Key Research and Development Program of China(No.2022YFB3805800)the National Natural Science Foundation of China(No.62175082)+2 种基金the Science,Technology and Innovation Commission of Shenzhen Municipality(No.JCYJ20190809105615053)the Huazhong University of Science and Technology Startup Funding(No.5003182125)the Multidisciplinary Research Support Program of Huazhong University of Science and Technology(No.2023JCYJ039)。
文摘Curvature sensing plays an important role in structural health monitoring,damage detection,real-time shape control,modification,etc.Developing curvature sensors with large measurement ranges,high sensitivity,and linearity remains a major challenge.In this study,a curvature sensor based on flexible one-dimensional photonic crystal(1D-PC)films was proposed.The flexible 1D-PC films composed of dense chalcogenide glass and water-soluble polymer materials were fabricated by solution processing.The flexible 1D-PC film curvature sensor has a wide measurement range of 33-133 m-1and a maximum sensitivity of0.26 nm/m^(-1).The shift of the transmission peak varies approximately linearly with the curvature in the entire measurement range.This kind of 1D-PC film curvature sensor provides a new idea for curvature sensing and measurement.
基金supported by the Major State Basic Research Development Program (No. 2014CB643503)the National Science Foundation for Post-doctoral Scientists of China (No. 2015M580512)partly supported by the program for Innovative Research Team in University of Ministry of Education of China (No. IRT13R54)
文摘A solution-processed CuOx film has been successfully integrated as the hole-transporting layer（HTL） for inverted planar heterojunction perovskite solar cells（PVSCs）. The CuOx layer is fabricated by simply spin-coating a copper acetylacetonate（Cu（acac）2） chloroform solution onto ITO glass with high transparency in the visible range. The compact and pinhole-free perovskite film with large grain domains is grown on the CuOx film. The inverted PVSCs with the structure of ITO/CuOx/MAPbI3/PC（61）BM/ZnO/Al are fabricated and show a best PCE of 17.43% under standard AM 1.5G simulated solar irradiation with a VOCof 1.03 V, aJ（SC） of 22.42 mA cm^（-2）, and a fill factor of 0.76, which is significantly higher and more stable than that fabricated from the often used hole-transporting material PEDOT：PSS（11.98%） under the same experimental conditions. The enhanced performance is attributed to the efficient hole extraction through the CuOx layer as well as the high-quality CH3NH3PbI3 films grown on the CuOx. Our results indicate that low-cost and solution-processed CuOx film is a promising HTL for high performance PVSCs with better stability.
基金This work was supported by the National Key Research and Devel-opment Program of China(2019YFA0210300)the NSF of China(21922802+4 种基金22220102003)the Beijing Natural Science Foundation(JQ19007)Talent cultivation of State Key Laboratory of Organic-Inorganic Composites“Double-First-Class”construction projects(XK180301,XK1804-02)Distinguished Scientist Program at BUCT(buctylkxj02).
文摘Covalent organic polymers(COPs)have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures.However,their layered stacks and limited solubility preclude further processing for large-scale applications in devices,especially optoelectronic equipment.Herein,a universal strategy to adjust the electron donor–acceptor(D-A)moieties of the building blocks in COPs is proposed,achieved by in situ charge exfoliation of COP blocks into few-layer true solutions in(Lewis)acid and base media.The electron D-A moieties of the building blocks endow the COPs with the ability to accept or donate electrons,by altering the electron cloud distribution as well as the relative energy levels of the frontier molecular orbitals.The resultant soluble COPs can easily be processed into a uniform film by solution processing via the spin-coat method.The obtained COP-N achieves efficient and stable perovskite electroluminescence as a novel hole injection material on indium tin oxide,and the operating lifetime for a perovskite quantum dot light-emitting diodes device exceeds that of a poly(ethylene dioxythiophene):polystyrene sulphonate counterpart.This straightforward electronic regulation strategy provides a new avenue for the rational synthesis of processable reticular molecular polymers for practical electronic devices.
基金Aziz FoundationDowning College,Cambridge+2 种基金Engineering and Physical Sciences Research Council,Grant/Award Numbers:EP/L016087/1,EP/P027032/1Isaac Newton TrustRoyal Academy of Engineering,Grant/Award Number:RF\201718\1701 and CieT1819\24。
文摘Nickel oxide(NiOx),a p-type oxide semiconductor,has gained significant attention due to its versatile and tunable properties.It has become one of the critical materials in wide range of electronics applications,including resistive switching random access memory devices and highly sensitive and selective sensor applications.In addition,the wide band gap and high work function,coupled with the low electron affinity,have made NiOx widely used in emerging optoelectronics and p-n heterojunctions.The properties of NiOx thin films depend strongly on the deposition method and conditions.Efficient implementation of NiOx in next-generation devices will require controllable growth and processing methods that can tailor the morphological and electronic properties of the material,but which are also compatible with flexible substrates.In this review,we link together the fundamental properties of NiOx with the chemical processing methods that have been developed to grow the material as thin films,and with its application in electronic devices.We focus solely on thin films,rather than NiOx incorporated with one-dimensional or two-dimensional materials.This review starts by discussing how the p-type nature of NiOx arises and how its stoichiometry affects its electronic and magnetic properties.We discuss the chemical deposition techniques for growing NiOx thin films,including chemical vapor deposition,atomic layer deposition,and a selection of solution processing approaches,and present examples of recent progress made in the implementation of NiOx thin films in devices,both on rigid and flexible substrates.Furthermore,we discuss the remaining challenges and limitations in the deposition of device-quality NiOx thin films with chemical growth methods.
基金The authors acknowledge financial support from the National Natural Science Foundation of china(NSFC)(Nos.50933003,20774047)the Ministry of Science and Technology of the People’s Repulic of China(MOST)(No.2009AA032304)Natural Science Foundation(NSF)of Tianjin City(No.08JCZDJC25300).
文摘Flexible organic field-effect transistors(OFETs)using solution-processable functionalized graphene for all the electrodes(source,drain,and gate)have been fabricated for the first time.These OFETs show performance comparable to corresponding devices using Au electrodes as the source/drain electrodes on SiO2/Si substrates with Si as the gate electrode.Also,these devices demonstrate excellent flexibility without performance degradation over severe bending cycles.Furthermore,inverter circuits have been designed and fabricated using these all-graphene-electrode OFETs.Our results demonstrate that the long-sought dream for all-carbon and flexible electronics is now much closer to reality.
