Preparation of CuCr1-xGaxO2 (0 ≤ x ≤ 1) nanocrystals for inorganic hole conductor of inverted perovskite solar cells

초록

CuGaO2 (CGO) and CuCrO2 (CCO) belonging to the delafossite family are attracting attention as potential inorganic hole-transporting materials (HTMs) for perovskite solar cells (PSCs). Herein, various solid solutions of CCO and CGO were prepared by hydrothermal reaction to obtain an optimal composition that leads to reproducible size control and high hole conductivity. The particle sizes of the prepared CuCr1-xGaxO2 (CCGO) were maintained at similar to 10 nm with a high uniformity until the Ga/Cr composition ratio was increased to 60/40, whereas the samples derived at the composition ratio of 70/30 or higher contain large disk-like structures. When they were applied as HTMs of the inverted PSC devices employing CH3NH3PbI3, the CCGO with Ga content of 60% provided the best photovoltaic properties. The achieved photovoltaic conversion efficiency was 16.38%, which is 27% and 22% higher than that of the PSCs with bare CCO and CGO, respectively.

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