Recent advances in CuSCN doping for electronic and photonic applications

Abstract

Copper(I) thiocyanate (CuSCN), which started from a hole conductor in all-solid-state dye-sensitized solar cells (DSSCs), has progressively become one of the standard p-type inorganic semiconductors or hole-transporting materials in an ever-expanding range of applications, from thin-film transistors (TFTs), sensors, organic light-emitting diodes (OLEDs) to various types of photovoltaics (PVs) and photodetectors (PDs). Its widespread use is based on its cost-effectiveness, solution-processability, high optical transparency, and a suitable electronic structure that enables hole transport while blocking electrons. However, there is plenty of room for improving its properties further, particularly hole mobility and p-type conductivity. To achieve this, various doping techniques have been reported, such as controlling native defects, passivating defects, doping with molecular electron acceptors, and doping by interlayer diffusion. This review summarizes recent doping methods, their underlying mechanisms, and the impact of doping on the development of CuSCN-based electronic and photonic devices. Improvements in hole-transporting characteristics have consistently enhanced device performance, and a deeper understanding of coordination chemistry, defects, and structural control is expected to continue pushing the advancements further.