Influence of N,N‑Dimethylformamide Annealing on the Local Electrical Properties of Organometal Halide Perovskite Solar Cells: an Atomic Force Microscopy Investigation
journal contributionposted on 2016-09-07, 00:00 authored by Jiang-Jun Li, Jing-Yuan Ma, Jin-Song Hu, Dong Wang, Li-Jun Wan
Organometal halide perovskites have been recognized as a new class of materials for photovoltaic application. Solvent annealing introduced during crystallization of bulk or thin-film materials can improve the performance of perovskite solar cells. Herein, we present Kelvin probe force microscopy and conductive atomic force microscopy (c-AFM) measurements to investigate the local optoelectronic properties of a perovskite film after N,N-dimethylformamide (DMF) annealing. AFM results show that DMF annealing induces recrystallization, yielding a large-size polycrystalline perovskite film. Uniform and higher photocurrent is distributed on the film. However, lower surface potential enhancement and photocurrent are observed at grain boundaries (GBs), illustrating that GBs acting as recombination sites are detrimental to photocurrent transport and collection. Our observation provides a nanoscale understanding of the device performance improvement after DMF annealing.