Design and Simulation of Ultra-Thin CdS-CdTe Thin-Film Solar Cell

Abstract

Cadmium telluride (CdTe) has long been recognized as a strong candidate for thin film solar cell applications. It has a band gap of 1.45 eV, which is nearly ideal for photovoltaic energy conversion. Due to its high optical absorption coefficient essentially all incident radiation with energy above its band-gap is absorbed within 1±2 mm from the surface. Thin film CdTe solar cells are typically hetero junctions, with cadmium sulfide (CdS) being the n-type junction partner.Cadmium telluride (CdTe) is the leading material for realization of low cost and high efficiency solar cell for terrestrial use. In this work, the CdTe conventional structure was investigated and achieved the maximum conversion efficiency of 25.16% with CdS. To explore the possibility of ultra-thin and high efficiency CdS-CdTe solar cell, the CdTe absorber layer and CdS window layer were decreased and found that 1 μm thin CdTe layer showed reasonable range of efficiency. Moreover, it was found that there were scopes to increase cell efficiency by reducing the cadmium sulfide (CdS) window layer thickness. The CdS window layer was reduced to 50 nm. All the simulation have been done using Analysis of Microelectronic and Photonic Structures (AMPS 1D) simulator. The maximum conversion efficiency of 25.16% (Voc= -1.078 V, Jsc= 26.330 mA/cm2, FF = -0.887) was achieved with 1 μm- CdTe absorber layer, 50 nm-CdS window layer.