A positive correlation between local photocurrent and grain size in a perovskite solar cell

Developing an interplay between the local morphological character and its local photovoltaic (PV) parameters in a perovskite thin film is essential for guiding the construction of highly-efficient perovskite solar cells (PSCs). To achieve a higher PSC performance, great efforts have been devoted to the growth of larger perovskite grains; however, how the gain size can influence the PSC performance in a working device remains unclear. Herein, using laser-scanned confocal microscopy coupled with a photocurrent detection module, we realize local photocurrent, photoluminescence (PL) intensity and PL lifetime mappings directly in a working PSC. For perovskite grains of various sizes (from -500 nm to a few micrometers), their local photocurrent exhibit a statically positive correlation with the grain size, but anti-correlated with the grain's local PL intensity. This result suggests that a larger perovskite grain likely has fewer defects and more importantly better interfacial contact with the charge collection layers and thus leads to higher charge collection efficiency, and the optimum grain size is found to be >2 lm. Our result provides important guidance to the growth and control of perovskite microstructures toward the further improvement of PSC performance. (c) 2022 Published by ELSEVIER B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

Automated summary

Developing an interplay between the local morphological character and its local photovoltaic (PV) parameters in a perovskite thin film is crucial for guiding the construction of highly-efficient perovskite solar cells (PSCs). The study finds that larger perovskite grains often have fewer defects and better charge collection efficiency, with the optimum grain size being >2 micrometers.