Wide-band-gap mixed-halide CH3NH3PbI3–XBrX-based solar cells have been prepared by means of a sequential spin-coating process. The spin-rate for PbI2 as well as its repetitive deposition are important in determining the cross-sectional shape and surface morphology of perovskite, and, consequently, J–V performance. A perovskite solar cell converted from PbI2 with a dense bottom layer and porous top layer achieved higher device performance than those of analogue cells with a dense PbI2 top layer. This work demonstrates a facile way to control PbI2 film configuration and morphology simply by modification of spin-coating parameters without any additional chemical or thermal post-treatment.
Bae, D., Palmstrom, A., Roelofs, K., Mei, B. T., Chorkendorf, I., Bent, S. F., & Vesborg, P. C. (2016). Tailoring Mixed-Halide, Wide-Gap Perovskites via Multistep Conversion Process. ACS applied materials & interfaces, 8(23), 14301-14306. https://doi.org/10.1021/acsami.6b01246