Design Simulation of Chalcogenide Absorber‐Based Heterojunction Solar Cell Yielding Manifold Enhancement in Efficiency

Abstract

We report, large efficiency improvement ∽4.5 times in a solar cell based on earth abundant low cost SnS absorber with configuration; Glass/Mo/SnS/CdS/i‐ZnO/AZO/Al in sharp contrast to prior experimental report in literature. Efficiency enhancement is attributed to tailored design at the absorber/buffer interface implemented via two‐step design modification vis‐à‐vis experimental benchmark. Design tailoring using simulation comprises substitution of sulfur composition in SnS by Se followed by replacing CdS buffer layer with wide bandgap, non‐toxic Zn (O, S). The effect of sulfur composition variation by Se (i.e. SnS1‐xSex) indicated an optimal Se mole fraction (x = 0.4) exhibiting maximum efficiency. In addition, optimization of the thickness, carrier density and bulk defect density of SnS1‐xSex absorber resulted in improved design. Replacing CdS buffer layer by ZnO1‐ySy in SnS absorber based solar cell resulted in substantial improvement in device parameters; open circuit voltage (VOC) ∽86% and current density (JSC) ∽78% due to optimal band alignment at the SnS1‐xSex/ZnO1‐ySy heterojunction. It occurred when the sulfur mole fraction is 60% in the absorber layer and 70% in the buffer layer causing efficiency rise to ∽17.87%. An optimal design comprising all the parameters including metal back contact work function, series and shunt resistance delivered an efficiency ∽19.2%.This article is protected by copyright. All rights reserved.