TCO and back contact buffer significance to achieve highest open circuit voltage and efficiency of CdTe solar cells

Abstract

CdTe thin film (TF) solar cells are most promising in commercial stage photovoltaic (PV) technologies. Cell contacts and interface defects related opto-electrical losses are still vital to limit its further technological benefit. Thin film PV cells voltage and fill factor loss lessening purpose carrier selective back contact selection with band matching interface layers are essential. Beside that buffer and active layer thickness selection is vital for field assisted selective carrier collection. The suitable emitter or buffer layer thickness and band gap matching to the active layer is potential to lessen parasitic absorption and shallow recombination loss. In this purpose SCAPS software based ZnO and SnO2 TCO as well as CdS and CdSe buffer impact are numerically analyzed. The TCO, emitter, back surface field layer and metal contacts effects on electrical performance is studied. In the model, TCO and back contact barrier thickness is shown significant to progress electrical performance. Eventually, open circuit voltage Voc = 0.9757 V and 19.92% efficiency is achieved for 90 nm of ZnTe BSF with ZnO TCO and CdS emitter layer of optimized thickness.