Antisolvent treatment of copper(i) thiocyanate (CuSCN) hole transport layer for efficiency improvements in organic solar cells and light-emitting diodes

Copper(i) thiocyanate (CuSCN) has been widely used as a hole-transport layer in organic optoelectronic devices. However, being a coordination polymer, its solution-processing is not straightforward; the typical process requires sulfide-based solvents that strongly interact with Cu(i). Herein, we show that a simple step of washing the CuSCN HTL with antisolvents, specifically acetone (Ace) or tetrahydrofuran (THF), can significantly increase the short-circuit current (J(sc)) and fill factor (FF) of organic photovoltaic (OPV) cells. The treatment leads to an increase in the average power conversion efficiency (PCE) from 8.18% for OPV devices based on untreated CuSCN to 9.16% and 9.25% for cells based on Ace- and THF-treated CuSCN HTL, respectively. Furthermore, for organic light-emitting diodes (OLEDs) based on CuSCN HTL, the treatment by THF also increases the external quantum efficiency (EQE) from 5.2% to 8.2%. The facile antisolvent treatment can be readily applied to the solution-processing of CuSCN which is already employed in various organic optoelectronic devices.

Automated summary

Treatment with antisolvents such as acetone or tetrahydrofuran can significantly improve the performance of organic photovoltaic and organic light-emitting diode devices based on copper(i) thiocyanate (CuSCN) as a hole-transport layer. This simple method increases short-circuit current (Jsc) and fill factor (FF) for OPV cells, as well as external quantum efficiency (EQE) for OLEDs, demonstrating enhanced power conversion efficiency and device efficiency.