Recent progress in doping of CuSCN for electronic and photonic applications

Abstract

Copper(I) thiocyanate (CuSCN) has emerged from a hole conductor in all-solid-state dye-sensitized solar cells (DSSCs) to 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). The widespread usage is based on its cost-effectiveness, solution-processability, high optical transparency, and suitable electronic structure that enables hole transport while blocking electrons. However, there is plenty of room for improving its properties further, particularly the hole mobility and p-type conductivity. In doing so, various doping techniques have been reported, such as controlling native defects, defect passivation, doping by molecular electron acceptors, or 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. The improvements in the hole transporting characteristics have consistently enhanced the device performance, and deeper understandings of coordination chemistry, defects, and structural control are expected to continue pushing the advancements further.