Song Jingfeng, Zhou Yuanyuan, Padture Nitin P, Huey Bryan D
Department of Materials Science and Engineering, University of Connecticut, Storrs, CT, 06269, USA.
School of Engineering, Brown University, Providence, RI, 02912, USA.
Nat Commun. 2020 Jul 3;11(1):3308. doi: 10.1038/s41467-020-17012-y.
While grain boundaries (GBs) in conventional inorganic semiconductors are frequently considered as detrimental for photogenerated carrier transport, their exact role remains obscure for the emerging hybrid perovskite semiconductors. A primary challenge for GB-property investigations is that experimentally they need to be performed at the top surface, which is not only insensitive to depth-dependent inhomogeneities but also could be susceptible to topographic artifacts. Accordingly, we have developed a unique approach based on tomographic atomic force microscopy, achieving a fully-3D, photogenerated carrier transport map at the nanoscale in hybrid perovskites. This reveals GBs serving as highly interconnected conducting channels for carrier transport. We have further discovered the coexistence of two GB types in hybrid perovskites, one exhibiting enhanced carrier mobilities, while the other is insipid. Our approach reveals otherwise inaccessible buried features and previously unresolved conduction pathways, crucial for optimizing hybrid perovskites for various optoelectronic applications including solar cells and photodetectors.
虽然传统无机半导体中的晶界通常被认为对光生载流子传输不利，但其在新兴的混合钙钛矿半导体中的具体作用仍不清楚。晶界性质研究的一个主要挑战是，实验需要在顶表面进行，这不仅对深度相关的不均匀性不敏感，而且可能容易受到形貌伪像的影响。因此，我们开发了一种基于断层扫描原子力显微镜的独特方法，在混合钙钛矿中实现了纳米尺度的全三维光生载流子传输图谱。这揭示了晶界作为载流子传输的高度互连导电通道。我们进一步发现混合钙钛矿中存在两种晶界类型，一种表现出增强的载流子迁移率，而另一种则平淡无奇。我们的方法揭示了原本无法访问的埋藏特征和以前未解决的传导途径，这对于优化包括太阳能电池和光电探测器在内的各种光电器件的混合钙钛矿至关重要。
