Dual Passivation of Perovskite Defects for Light-Emitting Diodes with External Quantum Efficiency Exceeding 20%
Dual Passivation of Perovskite Defects for Light-Emitting Diodes with External Quantum Efficiency Exceeding 20%
复制标题
Dual%20Passivation%20of%20Perovskite%20Defects%20for%20Light—Emitting%20Diodes%20with%20External%20Quantum%20Efficiency%20Exceeding%2020%
DOI：
10.1002/adfm.201909754
复制
发表时间：
2020-02-05
影响因子：
19
通讯作者：
Xiao, Zhengguo
中科院分区：
文献类型：
--
作者：
Fang, Zhibin;Chen, Wenjing;Xiao, Zhengguo
溶液处理的金属卤化物钙钛矿（MHP）由于其宽色域、高色纯度、可调谐发射波长、平衡电子/空穴输运等优点而在发光二极管（LED）中的应用引起了广泛的关注。尽管MHP对缺陷非常宽容，但溶液处理的钙钛矿LED（PeLED）中的缺陷仍然会导致严重的非辐射复合和器件不稳定性。在这里，分子设计的添加剂的双重钝化钙钛矿中的铅和卤化物缺陷的报道。采用简单的溶液法合成了双功能添加剂对氟苯甲基三氟乙酸铵（FPMATFA）。TFA阴离子和FPMA阳离子可以分别与配位不足的铅和卤素离子结合，导致铅和卤素缺陷的双重钝化。此外，大体积的FPMA基团可以抑制3D钙钛矿的晶粒生长，提高电子-空穴捕获率和辐射复合率。结果表明，采用甲脒铯碘化溴化铅（FA（0.33）Cs（0.67）Pb（I0.7Br 0.3）（3））制备的高性能PeLED的峰值外量子效率达到20.9%，发射波长为694 nm。此外，由于钙钛矿膜中的低陷阱密度，PeLED的工作寿命也大大提高。
Solution-processed metal halide perovskites (MHPs) have attracted much attention for applications in light-emitting diodes (LEDs) due to their wide color gamut, high color purity, tunable emission wavelength, balanced electron/hole transportation, etc. Although MHPs are very tolerant to defects, the defects in solution-processed perovskite LEDs (PeLEDs) still cause severe nonradiative recombination and device instability. Here, molecular design of additives for dual passivation of both lead and halide defects in perovskites is reported. A bi-functional additive, 4-fluorophenylmethylammonium-trifluoroacetate (FPMATFA), is synthesized by using a simple solution process. The TFA anions and FPMA cations can bond with undercoordinated lead and halide ions, respectively, resulting in dual passivation of both lead and halide defects. In addition, the bulky FPMA group can constrain the grain growth of 3D perovskite, enhancing electron-hole capture rates and radiative recombination rates. As a result, high-performance PeLEDs with a peak external quantum efficiency reaching 20.9% and emission wavelength at 694 nm are achieved using formamidinium-cesium lead iodide-bromide (FA(0.33)Cs(0.67)Pb(I0.7Br0.3)(3)). Furthermore, the operational lifetime of PeLEDs is also greatly improved due to the low trap density in the perovskite film.