Theoretical model and device performance of CuInS2 thin film solar cell

The capacitance vs. voltage characteristics and the current vs. voltage cha racteristics of the thin film solar cell consisting of a transparent conduc tive oxide/CdS/CuInS2 heterostructure are analyzed in terms of the theoreti cal device model where a very thin n-type CuInS2 layer exists on the top su rface of the p-type absorber layer. The CuInS2 absorber layer is prepared b y sulfurization of precursors deposited on a Mo-coated soda lime glass subs trate or a Pt foil substrate. When the absorber layer is prepared on the fo rmer the heterostructure is an abrupt junction in which the net acceptor co ncentration of the absorber layer is of the order of 10(16)-10(17) cm(-3), but when prepared on the latter it is a linearly graded junction in which t he gradient of the acceptor concentration lying in the order of 10(20)-10(2 1) cm(-4) is a decreasing function of precursor thickness. The highest open circuit voltage of 0.755 V is obtained in a solar cell that consists of th e thickest absorber layer prepared on the latter and hence exhibits the low est built-in electric field at the junction interface.