Performance optimization of high efficiency CdSeTe thin film solar cell with back-contact buffer layer using...

Electricity generated by CdTe thin film photovoltaic technology with a power conversion efficiency of 23% becomes a viable option for low-cost electricity production. However, the performance of CdTe based solar cells is limited by the poor compatibility of the back electrode with the high work function of the CdTe or CdSeTe absorber. A back contact buffer (BCB) layer modifies the interface by bridging electronic energy states, and facilitate a feasible charge transport. Here, we investigate the performance of the CdSeTe solar cell, featuring ITO/ZnO/MgZnO/CdSeTe/CuO/Pt, by employing a p-type CuO as BCB layer and Pt back electrode using numerical simulations. The band structure at the CuO/CdSeTe interface exhibits a cliff characterized by a conduction band offset of -0.21 eV and a valence band offset of -0.15 eV, which expedites hole transport to the back electrode through an Ohmic contact. The modified CdSeTe solar cell achieves a PCE of 27.04%, with a V_oc of 1.03 V, and a J_sc of 29.8 mA/cm², for an optimized absorber thickness (1400 nm), carrier concentration (10¹⁶/cm³), and defect density (10¹⁴/cm³), respectively. This study opens the pathways for the development of high-efficiency CdSeTe solar cells by engineered back contact with a suitable semiconductor back buffer layer.