Solution‐processed copper (I) thiocyanate (CuSCN) for highly efficient CdSe/CdTe thin‐film solar cells

Solution‐processed CuSCN serving as hole transport, electron reflecting layer (HTL, ERL) and Cu dopant source for CdSe/CdTe thin‐film solar has demonstrated high power conversion efficiency (PCE) of ~17%. Two types of solvent, diethyl sulfide (DES) and aqueous ammonia (NH4OH), are explored to deposit CuSCN on CdTe, and both can enhance the performance of CdSe/CdTe solar cells. However, NH4OH solvent is less toxicity, leading to a smoother surface than DES solvent, enabling the deposition of ultra‐thin CuSCN layer and avoiding the high cost of DES. Temperature‐dependent current‐voltage (J‐V‐T) and capacitance‐voltage (C‐V‐T) measurements reveal that the use of CuSCN HTL increases hole concentration in CdTe absorber and significantly reduces back‐contact barrier height. High power conversion efficiency is achievable with the optimal thickness of the CuSCN layer. Our results demonstrate solution‐processed CuSCN HTL for enhancing the efficiency and reducing the cost of CdTe thin‐film solar cells. Solution‐processed CuSCN serving as hole transport layer (HTL) and Cu dopant source for CdSe/CdTe thin‐film solar has demonstrated high power conversion efficiency (PCE) of ~17%. Two types of solvent, diethyl sulfide (DES) and aqueous ammonia (NH4OH), are explored to deposit CuSCN on CdTe, and both can enhance the performance of CdSe/CdTe solar cells with a reduced cost.