Influence of Substrate on Sb2Se3/CdS Heterojunction Thin Film Solar Cells and Evaluation of Their Performance by Dark J-V Analysis

Abstract

A simple binary antimony selenide (Sb₂Se₃) absorber is evolving as an alternative photovoltaic material in thin film solar cells because of its unique properties and easy processing. Sb₂Se₃ thin films having good crystalline quality are grown via versatile thermal evaporation from pre-synthesized near stoichiometric compound material on molybdenum-coated soda lime glass (SLG) and borosilicate glass (BG) substrates. Following the systematic characterizations on the absorber films, substrate configured Sb₂Se₃/CdS heterojunction devices were fabricated and their photovoltaic characteristics have been studied using current density vs. voltage (J-V), dark J-V modeling, external quantum efficiency and capacitance vs. voltage measurements. The power conservation efficiency values of 4.88% and 5.04% were achieved for the devices fabricated on SLG and BG substrates, respectively with deficit in open circuit voltage. The obtained values are higher in comparison to the reported device efficiencies in substrate configured Sb₂Se₃ solar cells, in which the absorber is prepared through thermal evaporation. To understand the loss in open circuit voltage_, a compact equivalent circuit model was considered and identified the contribution of different shunt leakage paths in the devices. In addition to that, the device fabricated on the SLG was stable with minimal changes in its photovoltaic performance for a period spanning over 200 days. The results obtained are encouraging with scope for improving the device performance through interface engineering and back surface passivation strategies.