Xue Ding-Jiang, Hou Yi, Liu Shun-Chang, Wei Mingyang, Chen Bin, Huang Ziru, Li Zongbao, Sun Bin, Proppe Andrew H, Dong Yitong, Saidaminov Makhsud I, Kelley Shana O, Hu Jin-Song, Sargent Edward H
Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, M5S 1A4, Canada.
Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, China.
Nat Commun. 2020 Mar 23;11(1):1514. doi: 10.1038/s41467-020-15338-1.
Thermally-induced tensile strain that remains in perovskite films following annealing results in increased ion migration and is a known factor in the instability of these materials. Previously-reported strain regulation methods for perovskite solar cells (PSCs) have utilized substrates with high thermal expansion coefficients that limits the processing temperature of perovskites and compromises power conversion efficiency. Here we compensate residual tensile strain by introducing an external compressive strain from the hole-transport layer. By using a hole-transport layer with high thermal expansion coefficient, we compensate the tensile strain in PSCs by elevating the processing temperature of hole-transport layer. We find that compressive strain increases the activation energy for ion migration, improving the stability of perovskite films. We achieve an efficiency of 16.4% for compressively-strained PSCs; and these retain 96% of their initial efficiencies after heating at 85 °C for 1000 hours-the most stable wide-bandgap perovskites (above 1.75 eV) reported so far.
退火后残留在钙钛矿薄膜中的热致拉伸应变会导致离子迁移增加，这是这些材料不稳定的一个已知因素。先前报道的用于钙钛矿太阳能电池（PSC）的应变调节方法使用了具有高热膨胀系数的衬底，这限制了钙钛矿的加工温度并损害了功率转换效率。在这里，我们通过从空穴传输层引入外部压缩应变来补偿残余拉伸应变。通过使用具有高热膨胀系数的空穴传输层，我们通过提高空穴传输层的加工温度来补偿PSC中的拉伸应变。我们发现压缩应变增加了离子迁移的活化能，提高了钙钛矿薄膜的稳定性。我们实现了压缩应变PSC的效率为16.4%；并且在85°C下加热1000小时后，这些PSC保留了其初始效率的96%——这是迄今为止报道的最稳定的宽带隙钙钛矿（高于1.75 eV）。
