Thermal vacuum evaporation of thin Cu(I)Br films for photovoltaic application

In the present study, thermally evaporated thin copper (I) bromide films were investigated as a potential hole-transport material for hybrid perovskite solar cells in a standard configuration. The films were deposited on top of glass substrates; the measured transparency was 80 %. The structural and morphological analyses revealed a dense polycrystalline structure of γ-CuBr. The analysis of the surface chemical composition demonstrated that copper was in a Cu1+ state and the films were stoichiometric. Electrical measurements were performed with deposited planar silver or copper electrodes. The layers were highly resistive; however, a current increasing with the time was observed when the samples were biased by a dc voltage of 20 V for two hours, which we speculate might be due to a possible new conduction mechanism.