Perovskite based light-emitting diodes(PeLEDs)have become a powerful candidate for next-generation solid-state lightings and high-definition displays due to their high photoluminescence quantum yield(PLQY),tunable emi...Perovskite based light-emitting diodes(PeLEDs)have become a powerful candidate for next-generation solid-state lightings and high-definition displays due to their high photoluminescence quantum yield(PLQY),tunable emission wavelength over the visible spectrum,and narrow emission linewidths.Over the past few years,the development of red-and green-emissive PeLEDs has rapidly increased,and the corresponding external quantum efficiencies(EQE)have exceeded 20%.However,the research progress of blue-emitting PeLEDs is limited by its poor material quality and inappropriate device structure.Currently,the maximum EQE of blue PeLED is only 6.2%,which is far from the industrialization requirements.In order to promote the development of blue PeLEDs,we summarize the recent research progress of blue perovskite materials and LEDs and discuss several fatal challenges,mainly embodied in low efficiency and poor stability.In order to overcome these challenges,detailed analysis and strategies are put forward in terms of the materials and devices.For the former,we summarize the feasible strategy for the preparation of efficient and stable blue-emissive perovskites using component engineering.For the latter,we analyze the advantages and limitations of the different strategies for blue-emissive perovskite in LEDs.At the end of the review,a comprehensive outlook is detailed,including future development directions and several technical problems to be solved.Thus,we aim to highlight the significance and promote the industrialization of PeLEDs.展开更多
PSR B2111+46 is studied and analyzed by the method of Gaussian fit separation of the average profile (GFSAP). It has been observed at six frequencies,408, 610, 925, 1408, 1640, and 4850 MHz, serving as an excellent sa...PSR B2111+46 is studied and analyzed by the method of Gaussian fit separation of the average profile (GFSAP). It has been observed at six frequencies,408, 610, 925, 1408, 1640, and 4850 MHz, serving as an excellent sample for a multifrequency analysis. Applying the GFSAP method we find that PSR B2111+46 hasfive components in its profile at all six frequencies. The result supports Rankin's 'core-double cone' model in emission region. On the basis of component decomposition, we discuss the geometrical structure of core, inner cone and outer cone, the emission beam radius, the emission region altitude and the geometry symmetry. We also examine the spectrum characteristics of core, inner cone and outercone. It is found that the spectrum of the core is steeper than the inner and outer cone.展开更多
The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed w...The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed wetlands,were investigated with laboratoryscale systems.N_(2)O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent,and the total N_(2)O emission in the system with middle COD influent concentration was the least.The relationships between N_(2)O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N_(2)O flux.The multiple linear regression model against principal components indicated that different water parameters affected N_(2)O flux with different COD concentrations in the influent,but nitrate nitrogen affected N_(2)O flux in all systems.展开更多
White-light emitting(WLE) polymers have attracted continuous attention for their promising applications in solid-state lighting,flexible display and related fields. However, achieving dual-emission and pure white-ligh...White-light emitting(WLE) polymers have attracted continuous attention for their promising applications in solid-state lighting,flexible display and related fields. However, achieving dual-emission and pure white-light emission in a single-component polymer is still challenging. In this study, a brominated single-component polymer Br OD-TFB was designed and synthesized,which shows dual-emission and white light emission properties in solution and room-temperature phosphorescence(RTP) in thin films. The dual-emission properties can be tuned by concentration, solvent polarity, and excitation energy. Spectral analyses and theoretical calculations reveal that the origin of the high-energy emission band(HEB) is intramolecular charge transfer(ICT)along the polymer chain, whilst the low-energy emission band(LEB) originates from the excited-state related to the intra-chain and inter-chain C–Br···π interactions as demonstrated by the single-crystal structure of the model compound. Appropriate control of the formation and the destruction of the halogen-assisted interactions can initiate white-light emission in the singlecomponent polymer. More interestingly, by dispersing Br OD-TFB(0.1 wt%) in a non-emissive, colorless and transparent polymer, the characteristics of this white-light emission can be fully demonstrated while exhibiting unexpected RTP properties,with photoluminescence quantum efficiency(Φ_(PL)) of up to 23% and CIE coordinates of(0.32, 0.32).展开更多
基金supported by NSFC(61604074,61725402)the National Key Research and Development Program of China(2016YFB0401701)+2 种基金the Natural Science Foundation of Jiangsu Province(BK20180020,BK20160827)the Fundamental Research Funds for the Central Universities(No.30917011202)PAPD of Jiangsu Higher Education Institutions,and large instrument equipment open fund of Nanjing University of Science and Technology.
文摘Perovskite based light-emitting diodes(PeLEDs)have become a powerful candidate for next-generation solid-state lightings and high-definition displays due to their high photoluminescence quantum yield(PLQY),tunable emission wavelength over the visible spectrum,and narrow emission linewidths.Over the past few years,the development of red-and green-emissive PeLEDs has rapidly increased,and the corresponding external quantum efficiencies(EQE)have exceeded 20%.However,the research progress of blue-emitting PeLEDs is limited by its poor material quality and inappropriate device structure.Currently,the maximum EQE of blue PeLED is only 6.2%,which is far from the industrialization requirements.In order to promote the development of blue PeLEDs,we summarize the recent research progress of blue perovskite materials and LEDs and discuss several fatal challenges,mainly embodied in low efficiency and poor stability.In order to overcome these challenges,detailed analysis and strategies are put forward in terms of the materials and devices.For the former,we summarize the feasible strategy for the preparation of efficient and stable blue-emissive perovskites using component engineering.For the latter,we analyze the advantages and limitations of the different strategies for blue-emissive perovskite in LEDs.At the end of the review,a comprehensive outlook is detailed,including future development directions and several technical problems to be solved.Thus,we aim to highlight the significance and promote the industrialization of PeLEDs.
文摘PSR B2111+46 is studied and analyzed by the method of Gaussian fit separation of the average profile (GFSAP). It has been observed at six frequencies,408, 610, 925, 1408, 1640, and 4850 MHz, serving as an excellent sample for a multifrequency analysis. Applying the GFSAP method we find that PSR B2111+46 hasfive components in its profile at all six frequencies. The result supports Rankin's 'core-double cone' model in emission region. On the basis of component decomposition, we discuss the geometrical structure of core, inner cone and outer cone, the emission beam radius, the emission region altitude and the geometry symmetry. We also examine the spectrum characteristics of core, inner cone and outercone. It is found that the spectrum of the core is steeper than the inner and outer cone.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50508019)the National Natural Science Foundation of China-Japan Science and Technology Agency(NSFC-JST)Strategic Joint Research Project(Grant No.50721140117).
文摘The effects of chemical oxygen demand(COD)concentration in the influent on nitrous oxide(N_(2)O)emissions,together with the relationships between N_(2)O and water quality parameters in free water surface constructed wetlands,were investigated with laboratoryscale systems.N_(2)O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent,and the total N_(2)O emission in the system with middle COD influent concentration was the least.The relationships between N_(2)O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N_(2)O flux.The multiple linear regression model against principal components indicated that different water parameters affected N_(2)O flux with different COD concentrations in the influent,but nitrate nitrogen affected N_(2)O flux in all systems.
基金supported by the National Natural Science Foundation of China(51873239,51373204,U20A20255)the Science and Technology Project of Guangdong Province(2015B090915003,2019B040401002,2020B010182001)+2 种基金National Basic Research Program of China(2014CB643605)the Leading Scientific,Technical and Innovation Talents of Guangdong Special Support Program(2016TX03C295)the Natural Science Foundation of Guangdong Province(2114050001078)。
文摘White-light emitting(WLE) polymers have attracted continuous attention for their promising applications in solid-state lighting,flexible display and related fields. However, achieving dual-emission and pure white-light emission in a single-component polymer is still challenging. In this study, a brominated single-component polymer Br OD-TFB was designed and synthesized,which shows dual-emission and white light emission properties in solution and room-temperature phosphorescence(RTP) in thin films. The dual-emission properties can be tuned by concentration, solvent polarity, and excitation energy. Spectral analyses and theoretical calculations reveal that the origin of the high-energy emission band(HEB) is intramolecular charge transfer(ICT)along the polymer chain, whilst the low-energy emission band(LEB) originates from the excited-state related to the intra-chain and inter-chain C–Br···π interactions as demonstrated by the single-crystal structure of the model compound. Appropriate control of the formation and the destruction of the halogen-assisted interactions can initiate white-light emission in the singlecomponent polymer. More interestingly, by dispersing Br OD-TFB(0.1 wt%) in a non-emissive, colorless and transparent polymer, the characteristics of this white-light emission can be fully demonstrated while exhibiting unexpected RTP properties,with photoluminescence quantum efficiency(Φ_(PL)) of up to 23% and CIE coordinates of(0.32, 0.32).
