Impact of Back Surface Field (BSF) Layers in Cadmium Telluride (CdTe) Solar Cells from Numerical Analysis

Abstract

Numerical simulation has been executed using Solar Cell Capacitance Simulator (SCAPS-1D) to study the possibility of favourable efficiency and stable CdS/CdTe cell in various cell configurations. A basic structure of CdS/CdTe cell is studied in this work with 4 𝜇m CdTe absorber layer and 100 nm tin oxide (SnO2) as front contact, 25 nm cadmium sulfide (CdS) as buffer layer, zinc telluride (ZnTe) is used as back surface field (BSF) material compared with ZnTe:Cu, Cu2Te and MoTe2 in order to reduce the minority carrier recombination at back surface field (BSF). The cell structure of glass/SnO2/CdS/CdTe/MoTe2 has shown the highest conversion efficiency of 17.04% (Voc=0.91V, Jsc=24.79 mA/cm2 , FF=75.41). These calculations have verified that SnO2 as buffer layer and MoTe2 as back contacts are suitable for an efficient CdS/CdTe cell. Also, it is found that a few nanometers (about 40 nm) of back surface layer is enough to achieve high conversion efficiency. When MoTe2 is used, high conversion efficiency of more than 17% has been achieved compared to other BSF materials.