Alkali assisted enhancement of CZTS absorber layer characteristics

CZTS (Copper Zinc Tin Sulphide) is a quartnery semiconductor consisting of elements which are abundantly available in nature and are completely non-toxic. Moreover it has a band gap of about 1.5 eV and an absorption coefficient of 10 4 cm -1 , making it an ideal material to be used as an absorber layer in solar cells. In the present work, CZTS thin films were grown by Ultrasonic Spray Pyrolysis on two different substrates; soda lime glass and borosilicate glass. Sodium was found to diffuse from the substrate into the film due to high growth temperatures. The crystallite size and electrical conductivity enhanced as a consequence of this alkali penetration into the films. The results are presented in this paper.