In this study, an environmental friendly heterostructure perovskite solar cell is constructed using non-toxic, lead-free double perovskite material (FA)2BiCuI6 as an active layer. The proposed device architecture is FTO/STO/(FA)2BiCuI6/GO/Pd. An extensive theoretical analysis and optimization is conducted using SCAPS-1D simulation tool. The thickness of absorber layer, shallow acceptor density, back metal contact and operating temperature are varied to optimize performance parameter of device. Optimized results have been observed at 700 nm absorber thickness for shallow acceptor density 1.0 × 1019 cm− 3 and 300 K operating temperature. A small value of series resistance 1 Ω cm2 along with high shunt resistance 100000 Ω cm2 is incorporated from the initial condition. The solar cell characteristics obtained are as open circuit voltage 1.10 V, short circuit current density 26.03 mA/cm2, fill factor 86.62 %, and device power conversion efficiency 24.69 %. The study concludes that the metal-work function can be carefully modulated to further enhance the performance characteristics of a device. Further current density–voltage characteristics (J-V), capacitance-voltage (C-V), and capacitance-frequency (C-f) characteristics have also been studied to explore the electrical characteristics of device. These findings suggest that a thorough analysis of materials could lead to their potential use as a high-performance active material for solar applications.