Integration of Sustainable Carbon Nanoparticles Into Inverted Hybrid Perovskite Solar Cells to Enhance Optoelectronic Performance

Hybrid Perovskite Solar Cells (HPSCs) using lead halide perovskites offer high performance and low-cost fabrication via solution processes. However, their environmental and thermal instability, along with poor polycrystalline quality—such as trap states and grain boundaries—limit device efficiency. In this study, we propose four novel compositions of carbon nanoparticles (CNPs) as additives for methylammonium PbI 3 (MAPI)-based HPSCs to enhance the optoelectronic performance. The CNPs are synthesized through a green, cost-effective method using citric acid and L-tryptophan for nitrogen doping. Their optical, structural, and morphological properties are thoroughly characterized prior to integration. To assess the impact of CNPs on perovskite crystallization and facet orientation, synchrotron-based 2D Grazing-Incidence Wide-Angle X-ray Scattering (GIWAXS) is employed. Devices are fabricated using an inverted architecture, suitable for flexible substrates and energy-efficient processing. Electrical and electrochemical impedance spectroscopy analyses reveal improved fill factors across all CNP compositions. The optimized system achieves a power conversion efficiency (PCE) of 10%, compared to 8.2% for the reference device without CNPs, confirming the potential of green CNPs to enhance HPSC performance without compromising structural integrity.