Defects Passivation via Potassium Iodide Post‐Treatment for Antimony Selenosulfide Solar Cells with Improved Performance

Abstract

Antimony selenosulfide (Sb2(S,Se)3) has been emerging as a promising light absorber in the past few years owing to tunable bandgap (1.1–1.7 eV), high absorption coefficient (>105 cm−1) and excellent phase and environmental stability. However, the efficiency of Sb2(S,Se)3 solar cells lags far behind the Shockley–Queisser limit. One of the critical obstacles originates from various extrinsic and intrinsic defects. They mostly locate in the deep energy levels and are prone to form recombination centers, inhibiting the improvement of device performance. Herein, surface post‐treatment via potassium iodide is introduced to fabricate high‐quality Sb2(S,Se)3 films and solar cells. The surface post‐treatment not only manipulates the crystal growth process to form compact films with larger grain size but also forms better band alignment and inhibits the formation of deep‐level defects antimony antisite (SbSe), thus improving the quality of heterojunction. Consequently, the resultant Sb2(S,Se)3 solar cells achieve a champion power conversion efficiency of 9.22%. This study provides a new strategy of passivating deep‐level intrinsic defects via surface post‐treatment for high‐efficiency Sb2(S,Se)3 solar cells.

A comprehensive insight into deep-level defect engineering in antimony chalcogenide solar cells

“…Li et al 85 investigated the role of potassium iodide (KI) surface treatment on Sb 2 (S,Se) 3 thin films and solar cells. KI treatment was found to successfully improve the crystallinity and morphology of the Sb 2 (S,Se) 3 films, inhibit the deep-level defects and improve the band alignment for efficient charge transport.…”

A Review of Carrier Transport in High‐Efficiency Sb2(S,Se)3 Solar Cells

“…Reproduced with permission. [ 88 ] Copyright 2022, John Wiley and Sons. d) Schematic illustration of an Sb 2 (S,Se) 3 solar cell based on a nanorod‐textured Sb 2 (S,Se) 3 bilayer absorber.…”

“…In a separate study, Li et al utilized KI posttreatment to passivate deep‐level defects in Sb 2 (S,Se) 3 films. [ 88 ] The treatment promoted the formation of SB–I chemical bonds (Figure 6c), resulting in the occupation of anion sites and deep‐level antisite defects (Sb Se and Sb S ). This KI treatment led to higher recombination resistance ( R rec ) and lower series resistance ( R s ), indicating effective suppression of carrier recombination.…”

Critical Review on Crystal Orientation Engineering of Antimony Chalcogenide Thin Film for Solar Cell Applications

“…[78] Li et al demonstrated that the posttreatment of Sb 2 (S x Se 1−x ) 3 films with potassium iodide in a vacuum annealing environment can enhance the [211] orientation. [103]…”