Design of high efficient and stable ultra-thin CdTe solar cells with ZnTe as a potential BSF

The polycrystalline ultra-thin cadmium telluride (CdTe) is familiar as the potential solar cell material for its higher efficiency, cost-effective, cell stability and clean generation of solar electricity. In this study, a numerical analysis has been performed utilizing AMPS (Analysis of Microelectronic and Photonic Structures) simulator to examine the cell performances (V_oc, J_sc, FF and conversion efficiency) of ultra-thin CdTe solar cell. During the research, reduction of CdTe layer was done in the proposed cell and found that 1μm absorber layer is enough for acceptable range for cell conversion efficiency. The possibility of this ultra-thin CdTe absorber layer was examined, as one with 100 nm ZnTe back surface field (BSF) layer to minimize the recombination losses at the back contact and to reduce the barrier height in the valence band of the proposed cell. Higher conversion efficiency of 22.53% (J_sc = 24.28 mA/cm², FF = 0.875, V_oc = 1.06 V) has been achieved with only 0.8 μm of CdTe absorber layer along with 100 nm ZnTe BSF where as conversion efficiency is 18.68% (J_sc = 21.47 mA/cm², FF = 0.85, V_oc = 1.02 V) without BSF layer. Moreover, the proposed CdTe solar cell showed better stability as the normalized efficiency of the proposed cell linearly decreased with the increasing operating temperature at the gradient of -0.16%/°C.