Numerical prediction on the photovoltaic performance of CZTS‐based thin film solar cell

Abstract This article presents an enormously effective Cu2ZnSnS4 (CZTS)‐based n‐ZnS/p‐CZTS/p+‐WSe2 thin film solar cell. The device has been studied by varying the thickness, doping concentration and defect density of each layer utilizing SCAPS‐1D simulation software. The power conversion efficiency (PCE) for n‐ZnS/p‐CZTS single heterojunction is 14.06% with the JSC = 20.26 mA cm−2, VOC = 0.88 V and FF = 78.59%, respectively. This PCE is elevated to 27.31% with the JSC = 33.72 mA cm−2, VOC = 0.97 V and FF = 83.75%, respectively due to insertion of WSe2 back surface field (BSF) layer in the same structure. The significant improvement of PCE mainly depends on short circuit current which is resulted due to WSe2 layer that absorbs sub‐band gap photons through tail‐states‐assisted (TSA) photon upconversion method. These entire results demonstrate the potential of WSe2 as BSF layer in CZTS‐based thin film solar cells.