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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