Interfacial modification strategy using hydroxyethyl cellulose for enhancing the performance of CsPbBr₃ perovskite solar cells

The performance of inorganic cesium lead bromide (CsPbBr₃) perovskite solar cells (PSCs), known for their inherent stability, is partly limited by morphological defects and radiative recombination losses. This study investigates the efficacy of hydroxyethyl cellulose (HEC) as a passivation agent to address these challenges. A systematic optimization of the interface modification, including solvent selection and HEC concentration, has been conducted. Close inspections of the modified materials properties confirm improved perovskite crystallinity and effective grain boundary passivation. Meanwhile, photoluminescence and electroimpedance spectroscopy measurement of HEC-modified samples demonstrate a reduction in radiative recombination and an increase in charge carrier lifetime. The optimized device produces a power conversion efficiency (PCE) of 5.78%, significantly surpassing the pristine device. The substantial improvement is attributed to the synergistic effect of reduced defect density, enhanced charge carrier transport, and suppressed interfacial charge recombination, thereby highlighting the potential of HEC as a versatile passivation agent for inorganic PSCs.