Cheng Guoqing, Liu Yan, Chen Tao, Chen Wenjing, Fang Zhibin, Zhang Ji, Ding Liming, Li Xinhua, Shi Tongfei, Xiao Zhengguo
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
ACS Appl Mater Interfaces. 2020 Apr 15;12(15):18084-18090. doi: 10.1021/acsami.9b23170. Epub 2020 Apr 1.
Stability is becoming a main issue for perovskite light-emitting diodes (PeLEDs), as their external quantum efficiency (EQE) has been boosted to above 20%. An all-inorganic perovskite, cesium lead iodide (CsPbI), has better stability than organic-inorganic hybrid perovskites but suffers from a transition to yellow δ-CsPbI phase at room temperature. Herein, we report stabilization of the α-CsPbI phase by in situ formation of perovskite nanocrystals (NCs). By incorporation of a proper ratio of bulky organoammonium halides, 4-fluoro-phenylmethylammonium iodide (4-F-PMAI), stable α-CsPbI films with nanometer-sized crystals can be obtained using a one-step spin-coating approach. The PeLEDs using α-CsPbI NC films as emitters show a pure red emission at 692 nm and a high EQE of 14.8%. The EQE is further boosted to 18.6% using CsPbIBr as the emissive layer. Furthermore, the PeLEDs show a very decent half-lifetime of over 1200 min and a shelf stability of over 2 months, much longer than that of hybrid PeLEDs.
随着钙钛矿发光二极管（PeLEDs）的外量子效率（EQE）提高到20%以上，稳定性正成为一个主要问题。全无机钙钛矿碘化铯铅（CsPbI）比有机-无机杂化钙钛矿具有更好的稳定性，但在室温下会转变为黄色的δ-CsPbI相。在此，我们报道了通过原位形成钙钛矿纳米晶体（NCs）来稳定α-CsPbI相。通过掺入适当比例的大体积有机卤化铵，4-氟苯基甲基碘化铵（4-F-PMAI），可以使用一步旋涂法获得具有纳米尺寸晶体的稳定α-CsPbI薄膜。使用α-CsPbI NC薄膜作为发光体的PeLEDs在692 nm处显示出纯红色发射，外量子效率高达14.8%。使用CsPbIBr作为发光层时外量子效率进一步提高到18.6%。此外，PeLEDs显示出非常良好的半衰期超过1200分钟，储存稳定性超过2个月
