School of Energy and Environment, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong.
ACS Appl Mater Interfaces. 2017 Nov 8;9(44):38467-38476. doi: 10.1021/acsami.7b10994. Epub 2017 Oct 30.
As the electron transport layer (ETL) of perovskite solar cells, oxide semiconductor zinc oxide (ZnO) has been attracting great attention due to its relatively high mobility, optical transparency, low-temperature fabrication, and good environment stability. However, the nature of ZnO will react with the patron on methylamine, which would deteriorate the performance of cells. Although many methods, including high-temperature annealing, doping, and surface modification, have been studied to improve the efficiency and stability of perovskite solar cells with ZnO ETL, devices remain relatively low in efficiency and stability. Herein, we adopted a novel multistep annealing method to deposit a porous PbI film and improved the quality and uniformity of perovskite films. The cells with ZnO ETL were fabricated at the temperature of <150 °C by solution processing. The power conversion efficiency (PCE) of the device fabricated by the novel annealing method increased from 15.5 to 17.5%. To enhance the thermal stability of CHNHPbI (MAPbI) on the ZnO surface, a thin layer of small molecule [6,6]-phenyl-C-butyric acid methyl ester (PCBM) was inserted between the ZnO layer and perovskite film. Interestingly, the PCE of PCBM-passivated cells could reach nearly 19.1%. To our best knowledge, this is the highest PCE value of ZnO-based perovskite solar cells until now. More importantly, PCBM modification could effectively suppress the decomposition of MAPbI and improve the thermal stability of cells. Therefore, the ZnO is a promising candidate of electron transport material for perovskite solar cells in future applications.
作为钙钛矿太阳能电池的电子传输层（ETL），氧化物半导体氧化锌（ZnO）由于其较高的迁移率、光学透明度、低温制备和良好的环境稳定性而受到极大关注。然而，ZnO 的性质会与甲胺的衬底发生反应，从而降低电池的性能。尽管已经研究了许多方法，包括高温退火、掺杂和表面改性，以提高具有 ZnO ETL 的钙钛矿太阳能电池的效率和稳定性，但器件的效率和稳定性仍然相对较低。在此，我们采用了一种新颖的多步退火方法来沉积多孔的 PbI 薄膜，从而改善钙钛矿薄膜的质量和均匀性。通过溶液处理在 <150°C 的温度下制备具有 ZnO ETL 的电池。通过新颖的退火方法制备的器件的功率转换效率（PCE）从 15.5%提高到 17.5%。为了增强 ZnO 表面上 CHNHPbI（MAPbI）的热稳定性，在 ZnO 层和钙钛矿薄膜之间插入了一层小分子[6,6]-苯基-C-丁酸甲酯（PCBM）。有趣的是，PCBM 钝化电池的 PCE 可达到近 19.1%。据我们所知，这是迄今为止基于 ZnO 的钙钛矿太阳能电池的最高 PCE 值。更重要的是，PCBM 修饰可以有效抑制 MAPbI 的分解并提高电池的热稳定性。因此，ZnO 是未来应用中钙钛矿太阳能电池的有前途的电子传输材料候选物。
