Xiao Xun, Li Wenhao, Fang Yanjun, Liu Ye, Shao Yuchuan, Yang Shuang, Zhao Jingjing, Dai Xuezeng, Zia Rashid, Huang Jinsong
Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, 27599, USA.
School of Engineering and Department of Physics, Brown University, Providence, RI, 02912, USA.
Nat Commun. 2020 May 5;11(1):2215. doi: 10.1038/s41467-020-16075-1.
Grain boundaries have been established to impact charge transport, recombination and thus the power conversion efficiency of metal halide perovskite thin film solar cells. As a special category of grain boundaries, ferroelastic twin boundaries have been recently discovered to exist in both CHNHPbI thin films and single crystals. However, their impact on the carrier transport and recombination in perovskites remains unexplored. Here, using the scanning photocurrent microscopy, we find that twin boundaries have negligible influence on the carrier transport across them. Photoluminescence (PL) imaging and the spatial-resolved PL intensity and lifetime scanning confirm the electronically benign nature of the twin boundaries, in striking contrast to regular grain boundaries which block the carrier transport and behave as the non-radiative recombination centers. Finally, the twin-boundary areas are found still easier to degrade than grain interior.
已证实晶界会影响电荷传输、复合,进而影响金属卤化物钙钛矿薄膜太阳能电池的功率转换效率。作为一类特殊的晶界,铁弹孪晶界最近被发现在CHNHPbI薄膜和单晶中均存在。然而,它们对钙钛矿中载流子传输和复合的影响仍未得到探索。在此,我们使用扫描光电流显微镜发现,孪晶界对载流子穿过它们的传输影响可忽略不计。光致发光(PL)成像以及空间分辨的PL强度和寿命扫描证实了孪晶界在电子学上是无害的,这与常规晶界形成鲜明对比,常规晶界会阻碍载流子传输并充当非辐射复合中心。最后,发现孪晶界区域仍比晶粒内部更容易降解。