Elucidating and Mitigating Degradation Processes in Perovskite Light-Emitting Diodes
Elucidating and Mitigating Degradation Processes in Perovskite Light-Emitting Diodes
复制标题
DOI：
10.1002/aenm.202002676
复制
发表时间：
2020-11-16
影响因子：
27.8
通讯作者：
Stranks, Samuel D.
中科院分区：
文献类型：
--
作者：
Andaji-Garmaroudi, Zahra;Abdi-Jalebi, Mojtaba;Stranks, Samuel D.
卤化物钙钛矿由于其作为破坏性显示和照明技术的潜力而引起了极大的兴趣。然而，钙钛矿发光二极管（PeLED）仍然受到操作稳定性差的阻碍。缺乏对降解过程的基本了解，但这将是减缓这些途径的关键。在此，使用操作中和非原位测量的组合来监测（Cs（0.06）FA（0.79）MA（0.15））Pb（I0.85Br0.15）（3）PeLED随时间的性能退化。通过器件，纳米级的横截面化学映射，和光学光谱测量，它揭示了性能下降产生的溴含量在一个接口，这导致注入的电荷载流子的障碍，从而增加非辐射复合的不可逆积累。通过用卤化钾钝化钙钛矿膜来阻止这种离子分离，卤化钾固定了过量的卤化物物质。钝化的PeLED显示出从0.5%到4.5%的增强的外部量子效率（EQE），并且重要的是，显示出显著增强的稳定性，即使在高电流密度（>200 mA cm（-2））下也具有最小的性能衰减。在峰值EQE下连续运行的器械的衰变半衰期从
Halide perovskites have attracted substantial interest for their potential as disruptive display and lighting technologies. However, perovskite light-emitting diodes (PeLEDs) are still hindered by poor operational stability. A fundamental understanding of the degradation processes is lacking but will be key to mitigating these pathways. Here, a combination of in operando and ex situ measurements to monitor the performance degradation of (Cs(0.06)FA(0.79)MA(0.15))Pb(I0.85Br0.15)(3) PeLEDs over time is used. Through device, nanoscale cross-sectional chemical mapping, and optical spectroscopy measurements, it is revealed that the degraded performance arises from an irreversible accumulation of bromide content at one interface, which leads to barriers to injection of charge carriers and thus increased nonradiative recombination. This ionic segregation is impeded by passivating the perovskite films with potassium halides, which immobilizes the excess halide species. The passivated PeLEDs show enhanced external quantum efficiency (EQE) from 0.5% to 4.5% and, importantly, show significantly enhanced stability, with minimal performance roll-off even at high current densities (>200 mA cm(-2)). The decay half-life for the devices under continuous operation at peak EQE increases from