Efficient materials for thin-film CdTe solar cell based on back surface field and distributed Bragg reflector

Abstract

Modifications in the physical properties of photovoltaic materials lead to enhanced conversion efficiency of a solar cell. This paper focuses on the suitable material selection for the cadmium telluride (CdTe) solar cell with special emphasis on improving the electrical parameters such as open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, and efficiency ƞ. Simulation results showed that materials having wide bandgap are more appropriate for each layer in the proposed cell compared to small-bandgap materials. Moreover, the back metal contact, which acts as electrode and also used as light reflector, usually suffers from high intrinsic absorption losses. To reduce such losses, we replaced the metal contact by a highly reflective one-dimensional distributed Bragg reflector, which increases the optical path length in greater amount over a broad span of incident angles and frequencies, and subsequently enhances the performance of the cell. The measured electrical parameters of the proposed cell under global AM 1.5G conditions are JSC = 25.036 mA/cm2, Voc = 1.065 V, FF = 87.56%, and ƞ = 23.94%, respectively.