A novel preparation method and investigation of sprayed CdS films

The main reason for the low photovoltaic efficiency of Cu₂S/CdS cells, in which the CdS film is deposited by solution spraying, is the very small average dimensions of the crystalline grains. The difficulty in depositing films with transverse dimensions of crystalline grains larger than 1 m is due to the fast decrease of substrate temperature during the spraying deposition of the CdS film. We have since arranged an experimental set-up able to maintain the surface temperature of the substrate constant. In this way it is possible to control the parameters which affect the deposition and to obtain a high degree of reproducibility of morphological properties. Average grain sizes of more than 1 m are obtained. We have investigated the crystalline grain sizes and the film thickness as a function of the deposition temperature and the spraying rate.Work supported by Ministero Pubblica Istruzione and Centro Regionale Ricerche Nucleari e Struttura della materia