Materials Physics and Application Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Nat Commun. 2016 May 16;7:11574. doi: 10.1038/ncomms11574.
Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0 °C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.
溶液处理的有机金属钙钛矿太阳能电池已成为最有前途的薄膜光伏技术之一。然而，一个关键的挑战是它们在长时间的太阳照射下缺乏稳定性。很少有研究调查过光浸泡对杂化钙钛矿的影响，并将光电性能的退化归因于光化学或场辅助离子迁移。在这里，我们表明，薄膜光伏器件中缓慢的光电流退化是由于形成了光激活的亚稳深能级陷阱态。然而，通过将器件在黑暗中放置<1 分钟，或者将器件在 0°C 下运行，可以完全自我修复；也可以完全防止降解。我们研究了几种物理机制来解释这些陷阱态形成的微观起源，其中涉及局部协同晶格应变和分子取向的小极化子态的形成作为一个可信的微观机制，需要进一步的详细研究。
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