Highly efficient Cesium Titanium (IV) Bromide perovskite solar cell and its point defect investigation: A computational study

Abstract

Lead-free, halide-based perovskites are drawing appreciable attention for solar cell applications due to the non-toxic nature and stable performance in ambient environment. In this study, we investigated different facets of a Cesium Titanium (IV) Bromide (Cs 2 TiBr 6 ) perovskite solar cell (PSC) with ZnO and MoO 3 as charge transport materials. Upon numerical optimization of perovskite layer thickness, its defect density , and the interface defect density, we propose a highly efficient, practically realizable PSC with a power conversion efficiency of 18.15%. Besides, we investigated different point defects in Cs 2 TiBr 6 and the effect of their electronic band positions on the PSC performance. It is found that for Cs 2 TiBr 6 based PSC applications, the material processing of Cs 2 TiBr 6 is a crucial aspect and the PSC may underperform for deep defect states (0.2 eV ~ 1.6 eV) with defect density over 10 15 cm −3 . In addition, we analyzed different back contact materials and found that carbon-based back contact can be a low-cost solution to gold for Cs 2 TiBr 6 PSCs. • A Cesium Titanium (IV) Bromide (Cs 2 TiBr 6 ) based perovskite solar cell with FTO/ZnO/Cs 2 TiBr 6 /MoO 3 /Au structure is proposed. • An optimum power conversion efficiency (PCE) of 18.15% is achieved. • Investigation on possible point defects in Cs 2 TiBr 6 and their electronic band position's effect on the PSC performance. • For deep defect state (0.2 eV ~ 1.6 eV) and defect density over 10 15 cm −3 , the PSC tends to underperform. • Carbon-based back contact can be a possible low cost replacement of gold for Cs 2 TiBr 6 PSCs.