A comprehensive analysis of PV cell parameters with varying halides stoichiometry in mixed halide perovskite solar cells

The optimized halide stoichiometry in mixed-halide perovskites offers the enhanced photophysical properties of perovskites films for efficient and stable perovskites solar cells (PSCs). Herein, a comprehensive analysis of the impact of the variation of cationic bromide (CH₃NH₃Br or MABr) concentration on the performance parameters of mixed halide (MAPbI_3-xBr_x) PSCs have been presented. It was noted that with an increase of MABr concentration from 10 to 70 mg/ml, open-circuit voltage (V_oc) increases from 942 mV to 992 mV, short circuit current density (J_sc) decreases from 19.83 mA/cm² to 12.36 mA/cm². Device having 20 mg/ml MABr exhibits best performance with an efficiency η = 12.18%, V_oc = 0.96 V, J_sc = 18.99 mA/cm² and fill factor (FF) = 0.67. Furthermore, photovoltaic (PV) cell parameters, i.e., J_ph, R_sh, R_s, n, and J₀ were analytically extracted and analyzed to recognize the influence of MABr. The best performing devices exhibits a higher photocurrent density: J_ph = 19.16 mA/cm², optimum device resistances: R_sh=869.57 Ω-cm², R_s = 7.91 Ω-cm², minimum value of ideality factor n = 1.52 and negligible leakage current density: J₀ = 3.95 × 10⁻¹³ mA/cm². The predicted PV cell parameters suggest that the best performing device possesses optimum morphology, lowest leakage current, and reduced recombination of charge carriers.