The Cu2SnS3/AZnO p-n heterojunction was fabricated and the structural and optical properties of the films were studied. The phase formation and the crystallite size of the films was analysed using X-ray diffraction. The morphology was studied using field emission scanning electron microscopy and transmission electron microscopy. The temperature dependent photoluminescence studies were conducted from 123 K to 353 K. The various possible transitions corresponding to the luminescence peaks were indexed. The intensities of the peaks were found to decrease with increase in temperature whereas there was found to be no change in the energy of emission. The chromaticity coordinates for the CTS/AZO heterojunction for different temperatures were found and it corresponded to white light emission at all temperatures.