Li Qi, Zhao Yicheng, Fu Rui, Zhou Wenke, Zhao Yao, Liu Xin, Yu Dapeng, Zhao Qing
State Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing, 100871, China.
Collaborative Innovation Center of Quantum Matter, Beijing, 100084, China.
Adv Mater. 2018 Aug 23:e1803095. doi: 10.1002/adma.201803095.
The fabrication of high-quality perovskite film highly relies on chemical composition and the synthesis method of perovskite. So far, sequentially deposited MA FA Pb(I Br ) polycrystalline film is adopted to produce high-performance perovskite solar cells with record power conversion efficiency (PCE). Fewer grain boundaries and incorporation of inorganic cation (e.g., cesium) would further increase device performance via sequential deposition. Here, cesium chloride (CsCl) is introduced into lead iodide (PbI ) precursor solution that beneficially modulates the property of PbI film, leading to larger grains with cesium incorporation in the resulting perovskite film. The enlarged crystal grains originate from a slower nucleation process for CsCl-containing PbI film when reacting with formamidine iodide, confirmed by in situ confocal photoluminescence imaging. Photovoltaic devices based on CsCl-containing PbI film demonstrate a higher averaging efficiency of 21.3% than 20.3% of the devices without CsCl additives for reverse scan. More importantly, the device stability is improved by CsCl additives that retain over 90% of their initial PCE value after 4000 min tracking at maximum power point under 1-sun illumination. This work paves a way to further improve the photovoltaic performance of mixed-cation-halide perovskite solar cells via a sequential deposition method.
高质量钙钛矿薄膜的制备高度依赖于钙钛矿的化学成分和合成方法。到目前为止，采用顺序沉积的MA FA Pb(I Br )多晶薄膜来制备具有创纪录功率转换效率（PCE）的高性能钙钛矿太阳能电池。更少的晶界和无机阳离子（如铯）的掺入将通过顺序沉积进一步提高器件性能。在此，将氯化铯（CsCl）引入碘化铅（PbI ）前驱体溶液中，这有利于调节PbI 薄膜的性质，从而在所得钙钛矿薄膜中形成掺入铯的更大晶粒。原位共聚焦光致发光成像证实，含CsCl的PbI 薄膜与碘化甲脒反应时，其成核过程较慢，由此产生了更大的晶粒。基于含CsCl的PbI 薄膜的光伏器件在反向扫描时的平均效率为21.3%，高于不含CsCl添加剂的器件的20.3%。更重要的是，CsCl添加剂提高了器件稳定性，在1个太阳光照下最大功率点跟踪4000分钟后，器件仍保持其初始PCE值的90%以上。这项工作为通过顺序沉积方法进一步提高混合阳离子卤化物钙钛矿太阳能电池的光伏性能铺平了道路。
