Stable copper‐based 2D perovskite (NH₃C₃H₆NH₃)CuBr₄ thin film processed from green solvent for thermoelectric application

Abstract Great achievements about lead‐based halide perovskites have been made in the fields of photovoltaic solar cells, light emitting diodes, photodetectors, and thermoelectric devices. However, the toxicity and instability of lead‐based materials hinder their practical application. Herein, we used propane‐1,3‐diammonium cation to construct a copper‐based halide perovskite material (NH₃C₃H₆NH₃)CuBr₄ with a two‐dimensional layered structure. This material exhibits a suitable bandgap of 1.71 eV for a broad‐band absorption. Dense and flexible (NH₃C₃H₆NH₃)CuBr₄ thin film can be obtained by simple spin‐coating of the solution using green solvent DMSO. Furthermore, (NH₃C₃H₆NH₃)CuBr₄ shows excellent stability towards temperature, humidity and UV‐light. Finally, the (NH₃C₃H₆NH₃)CuBr₄ thin film shows a reasonable Seebeck coefficient of −13.8 μV K⁻¹ and a power factor of 1.70 μW m⁻¹ K⁻² at 298 K, demonstrating the great potential for flexible n‐type thermoelectric application. image