Low-Cost Alternatives for the Hole Transport Layer Spiro-OMeTAD in Lead-Free Perovskite Solar Cells Using Numerical Simulation

Abstract

     Lead‑free perovskites such as CsSnI₃ are promising absorber for sustainable solar energy; however, their performance is highly dependent on the choice of hole transport layer (HTL). In this work, SCAPS‑1D simulations (calibrated with experimental data) were employed to investigate a wide range of materials (Cu₂O, CZTSe, CBTS, CuSCN, CuO, Spiro‑IA, MoO₃, PTAA, GaAs, CuSbS₂, MoS₂, P3HT, PEDOT:PSS, CIS) as low‑cost alternatives to Spiro‑OMeTAD. Results indicate that the short‑circuit current density (Jsc) remained nearly constant in the range of (30–32 mA/cm²) for most cases, while the open‑circuit voltage (Voc) and fill factor (FF) varied depending on the material. Materials such as Cu₂O, CZTSe, and CBTS achieved the highest efficiencies (PCE ≈ 20–21%) with (Voc ≈ 0.91 V) and (FF ≈ 70–72%). They were followed by CuSCN, CuO, and Spiro‑IA, which exhibited good efficiencies (PCE ≈ 19–20%) with (Voc ≈ 0.88–0.89 V) and            (FF ≈ 67–69%). Other materials such as MoO₃, PTAA, and GaAs showed acceptable efficiencies (PCE ≈ 17–18%) with (Voc ≈ 0.88–0.90 V) and (FF ≈ 63–66%), whereas CuSbS₂, MoS₂, P3HT, PEDOT:PSS, and CIS were lower efficiencies (PCE ≈ 15–16%) with (Voc ≈ 0.81–0.85 V) and (FF ≈ 54–60%). This study confirms that the availability of several HTL layers that can serve as low‑cost alternatives to Spiro‑OMeTAD.