Suchergebnisse

Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs. ; Funding Agencies|ERC Starting grantEuropean Research Council (ERC) [717026]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; China Scholarship Council (CSC)China Scholarship Council

Black phase CsPbI3 is attractive for optoelectronic devices, while usually it has a high formation energy and requires an annealing temperature of above 300 degrees C. The formation energy can be significantly reduced by adding HI in the precursor. However, the resulting films are not suitable for light-emitting applications due to the high trap densities and low photoluminescence quantum efficiencies, and the low temperature formation mechanism is not well understood yet. Here, we demonstrate a general approach for deposition of gamma -CsPbI3 films at 100 degrees C with high photoluminescence quantum efficiencies by adding organic ammonium cations, and the resulting light-emitting diode exhibits an external quantum efficiency of 10.4% with suppressed efficiency roll-off. We reveal that the low-temperature crystallization process is due to the formation of low-dimensional intermediate states, and followed by interionic exchange. This work provides perspectives to tune phase transition pathway at low temperature for CsPbI3 device applications. Exploiting low-temperature formed black phase CsPbI3 for light-emitting applications remains a challenge. Here, the authors propose a method to enable the deposition of gamma -CsPbI3 films at 100C and demonstrate a light-emitting diode with an external quantum efficiency of 10.4% with suppressed efficiency roll-off. ; Funding Agencies|Major Research Plan of the National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [91733302]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [51703094, 61935017, 61974066]; Natural Science Foundation of Jiangsu Province, ChinaNatural Science Foundation of Jiangsu Province [BK20170991]; National Science Fund for Distinguished Young ScholarsNational Natural Science Foundation of China (NSFC)National Science Fund for Distinguished Young Scholars [61725502]; Major Program of Natural Science Research of Jiangsu Higher Education Institutions of China [18KJA510002]; National Key Research and Development Program of China [2018YFB0406704]; Natural Science Fund for Colleges and Universities in Jiangsu Province of China [17KJB150023]; ERC Starting GrantEuropean Research Council (ERC) [717026]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Marie Skodowska-Curie [798861]; Linkoping University