Modelling Insights of Sb₂(S,Se)₃ Solar Cells Using Triazatruxene Hole Transport Layers

Abstract Sb 2 (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/Sb 2 (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 Sb 2 (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 V OC (≈1 V), J SC >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 V OC loss (≈0.4 V), enhanced QE (>70%), reduced recombination (by a factor of 3 × 10 18 cm −3 s −1 ), and stronger electric fields, positioning triazatruxene‐based HTLs as a cost‐effective alternative to Spiro‐OMeTAD, significantly boosting Sb 2 (S,Se) 3 solar cell performance.