COUPLED OPTIMIZATION OF DEFECT DENSITY, ABSORBER PROPERTIES, AND INTERFACES FOR HIGH-PERFORMANCE PEROVSKITE SOLAR CELLS: A SCAPS-1D STUDY

Abstract

The optimization of defect density is a critical factor governing the photovoltaic performance of perovskite solar cells. The SCAPS-1D simulation results demonstrate that reducing the bulk trap density from 10¹⁵ to 10¹⁰ cm⁻³ substantially improves the device performance by suppressing trap-assisted non-radiative recombination and enhancing the effective lifetime of photogenerated charge carriers. The reduced recombination rate facilitates efficient carrier transport and collection, resulting in improvements in the open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE). These findings emphasize the importance of defect passivation and improved material quality for achieving high-performance perovskite photovoltaic devices. However, the beneficial effects associated with lower bulk defect densities can be limited by imperfections present at the semiconductor surface and heterointerfaces. Surface contamination and interfacial defects may generate localized electronic states that act as recombination centers and adversely influence charge extraction. Such imperfections can lead to undesirable phenomena, including Fermi-level pinning and enhanced recombination losses, thereby reducing the potential performance improvement obtained through bulk defect reduction. Therefore, effective surface and interface engineering is essential for maintaining favorable energy-level alignment and minimizing carrier losses. The comprehensive SCAPS-1D analysis further confirms that the photovoltaic performance of perovskite solar cells depends on the simultaneous optimization of multiple device parameters. An appropriate absorber bandgap is necessary for efficient solar-spectrum utilization, whereas an optimized absorber thickness provides sufficient optical absorption without introducing excessive recombination losses. Similarly, low defect density improves carrier lifetime, while carefully controlled donor and acceptor concentrations promote efficient charge separation and transport. The results indicate that these parameters are strongly interdependent and should be optimized collectively rather than independently. Overall, the study demonstrates that the combined optimization of absorber bandgap, thickness, defect density, doping concentration, and interfacial properties provides an effective pathway toward achieving enhanced photovoltaic performance and improved device efficiency in perovskite solar cells.