Abstract

Sb2(S,Se)3 is a promising thin-film solar absorber with a tunable bandgap (1.3–1.7 eV) and earth-abundant composition, yet its maximum reported efficiency (10.75%) in FTO/CdS/Sb2(S,Se)3/Spiro-OMeTAD/Au remains below the Shockley-Queisser limit. Moreover, the high cost of Spiro-OMeTAD as an HTL limits commercialization. Herein cost-effective triazatruxene-based HTLs (CI-B2, CI-B3, TAT-H, TAT-TY1, TAT-TY2) are introduced for the first time in Sb2(S,Se)3 solar cells and optimize device performance using SCAPS-1D. After replicating the experimental efficiency, optimization of HTL, ETL, and absorber parameters results in VOC (?1 V), JSC >30 mA cm?2), and FF (72–74%). Overall, efficiencies of 22.97%, 23.09%, 22.47%, 21.08%, 23.24%, and 23.11% are achieved for Spiro-OMeTAD, CI-B2, CI-B3, TAT-H, TAT-TY1, and TAT-TY2, respectively, owing to the reduced VOC loss (?0.4 V), enhanced QE (>70%), reduced recombination (by a factor of 3 × 1018 cm?3s?1), and stronger electric fields, positioning triazatruxene-based HTLs as a cost-effective alternative to Spiro-OMeTAD, significantly boosting Sb2(S,Se)3 solar cell performance. © 2025 Wiley-VCH GmbH.