A simple synthesis of transparent and highly conducting p-type Cu Al S nanocomposite thin films as the hole transporting layer for organic solar cells.

Inorganic p-type films with high mobility are very important for opto-electronic applications. It is very difficult to synthesize p-type films with a wider, tunable band gap energy and suitable band energy levels. In this research, p-type copper aluminum sulfide (Cu Al S ) films with tunable optical band gap, carrier density, hole mobility and conductivity were first synthesized using a simple, low cost and low temperature chemical bath deposition method. These fabricated Cu Al S films were deposited at 60 °C using an aqueous solution of copper(ii) chloride dihydrate (CuCl·2HO), aluminium nitrate nonohydrate [Al(NO)·9HO], thiourea [(NH)CS], and ammonium hydroxide, with citric acid as the complexing agent. Upon varying the ratio of the precursor, the band gap of the Cu Al S films can be tuned from 2.63 eV to 4.01 eV. The highest hole mobility obtained was 1.52 cm V s and the best conductivity obtained was 546 S cm. The Cu Al S films were used as a hole transporting layer (HTL) in organic solar cells (OSCs), and a good performance of the OSCs was demonstrated using the Cu Al S films as the HTL. These results demonstrate the remarkable potential of Cu Al S as hole transport material for opto-electronic devices.