Improving efficiency of planar hybrid CH3NH3PbI3−xClx perovskite solar cells by isopropanol solvent treatment

•Planar heterojunction CH3NH3PbI3−xClx perovskite solar cells were fabricated through a low-temperature solution process.•The performance of perovskite solar cells was enhanced after isopropanol treatment.•The improved performance was attributed to the remove of excess CH3NH3I in perovskite film and modified interfacial properties.

Hybrid organic/inorganic perovskite planar heterojunction (PHJ) solar cells are becoming one of the most competitive emerging technologies. Here, the devices (ITO/PEDOT:PSS/CH3NH3PbI3−xClx/PC60BM/C60/Al) are fabricated based on solution process. A power conversion efficiency (PCE) up to 13.1% was obtained after isopropanol (IPA) solvent treatment, which was 9% improvement than that of the original devices. Photocurrent hysteresis could be reduced to a certain extent by introducing IPA treatment. Solvent treatment can remove as-grown impurities like CH3NH3I and defects formed during the device fabrication. We also demonstrated the electrical and optical properties of perovskite films were improved. The addition of IPA-treated facilitates the formation of a relatively smooth PC60BM films. This work provides a very simple but effective strategy to enhance the power conversion efficiency of perovskite solar cells.

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