Li Dongni, Wang Qiuwen, Zhao Lu, Sun Xiangyu, Song Tinglu, Liu Fangze, Wei Jing, Li Hongbo
Beijing Key Laboratory of Construction-Tailorable Advanced Functional, Materials and Green Applications, Experimental Center of Advanced Materials School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
Nanotechnology. 2022 Jul 14;33(40). doi: 10.1088/1361-6528/ac73a6.
Metal halide perovskite solar cells (PSCs) have developed rapidly in recent years, due to their high performance and low-cost solution-based fabrication process. These excellent properties are mainly attributed to the high defect tolerance of polycrystalline perovskite films. Meanwhile, these defects can also facilitate ion migration and carrier recombination, which cause the device performance and the long-term stability of PSCs to deteriorate heavily. Therefore, it is critical to passivate the defects, especially at the surfaces of perovskite grains where the defects are most concentrated due to the dangling bonds. Here we propose a surface-capping engineering (SCE) method to construct 'dangling-bond-free' surfaces for perovskite grains. Diamine iodide (methylenediammonium diiodide, MDAI) was used to construct an electroneutral PbX-MDA-PbX(X = Cl, Br or I) layer at the perovskite surfaces. Compared to the monovalent FAwhich can only coordinate one [PbX]slab, the bivalent MDAcan coordinate two [PbX]slabs on both sides, thus realizing a dangling-bond-free surface. Solar cells based on SCE-perovskite films exhibited a higher power conversion efficiency (PCE) of 21.6%, compared with 19.9% of the control group; and maintained over 96% of its initial PCE after 13 h during the maximum power point tracking test under continuous AM1.5G illumination, whereas the control group only lasted 1.5 h. Constructing a dangling-bond-free capping layer on the grain boundary opens new avenues for the fabrication of ultralow-defect polycrystalline semiconductors, paving the way to further improve the PCE and lifetime of PSCs.
近年来，金属卤化物钙钛矿太阳能电池（PSCs）发展迅速，这得益于其高性能以及基于溶液的低成本制造工艺。这些优异性能主要归因于多晶钙钛矿薄膜的高缺陷容忍度。同时，这些缺陷也会促进离子迁移和载流子复合，从而导致PSCs的器件性能和长期稳定性严重下降。因此，钝化这些缺陷至关重要，尤其是在钙钛矿晶粒表面，由于悬空键的存在，这些表面的缺陷最为集中。在此，我们提出一种表面封端工程（SCE）方法，为钙钛矿晶粒构建“无悬空键”表面。使用二胺碘化物（亚甲基二铵二碘化物，MDAI）在钙钛矿表面构建一个电中性的PbX-MDA-PbX（X = Cl、Br或I）层。与只能配位一个[PbX]板的单价FA相比，二价MDA可以在两侧配位两个[PbX]板，从而实现无悬空键表面。基于SCE-钙钛矿薄膜的太阳能电池表现出更高的功率转换效率（PCE），为21.6%，而对照组为19.9%；在连续AM1.5G光照下的最大功率点跟踪测试中，13小时后其初始PCE保持在96%以上，而对照组仅持续了1.5小时。在晶界上构建无悬空键的封端层为制造超低缺陷多晶半导体开辟了新途径，为进一步提高PSCs的PCE和寿命铺平了道路。
