Design of high performance and ultra-thin CdTe solar cells with SnTe BSF from numerical analysis

Polycrystalline Cadmium Telluride (CdTe) is one of the leading solar cell materials for its efficiency, cost-effective and thermal stability. In this research work, numerical analysis is done by AMPS (Analysis of Microelectronic and Photonic Structures) simulator to investigate the cell performances (Jsc, FF, Voc, efficiency and temperature stability) of ultra-thin CdTe solar cell. Reduction of absorber layer was done and observed that 1 μm absorber layer is enough for acceptable range of cell conversion efficiency in the proposed cell. The possibility of this ultra-thin CdTe absorber layer was investigated, together with 100 nm SnTe back surface field (BSF) layer to reduce the barrier height in the valence band and to minimize the recombination losses at the back contact of the CdTe PV cell. From the investigation, it was found that the proposed ultra-thin cell have conversion efficiency of 18.68% (Jsc = 21.47 mA/cm2, FF = 0.85, Voc = 1.02 V) without BSF and with 100 nm SnTe BSF conversion efficiency increased to 22.61% (Jsc = 24.27 mA/cm2, FF = 0.876, Voc = 1.06 V) with only 0.7 μm of CdTe absorber layer. Moreover, without BSF and with SnTe BSF, the normalized efficiency of the proposed cell was linearly decreased with the increasing operating temperature at the gradient of -0.18%/°C and -0.16%/°C found in this analysis respectively, which indicated better stability of the proposed CdTe solar cell.