Defect suppression and crystallization modulation of SnO2 via KCl modification for enhanced performance of carbon-based perovskite solar cells

In situ KCl doping regulates SnO 2 via CBD. • Synergistic Cl − passivation reduces defects in SnO 2 . • SnO 2 modification improves perovskite crystallization. • Carbon-based devices deliver high efficiency and low hysteresis. Perovskite solar cells (PSCs) have attracted significant attention due to their high power conversion efficiency and low-cost fabrication. However, interfacial defects and inefficient charge transport at the electron transport layer (ETL)/perovskite interface remain critical challenges limiting device performance and stability. In this work, a KCl-modified SnO 2 ETL is developed via a chemical bath deposition (CBD) strategy to enhance interfacial properties and charge transport dynamics. The incorporation of KCl effectively passivates oxygen vacancies and undercoordinated Sn 4+ defects in SnO 2 , leading to improved film crystallinity and reduced defect density. As a result, charge extraction is facilitated and non-radiative recombination is suppressed. The optimized device achieves a power conversion efficiency (PCE) of 15.13%, representing a 7.22% enhancement compared to the pristine device. Furthermore, the modified devices exhibit reduced hysteresis, improved moisture resistance, and enhanced long-term stability, retaining 74.2% of the initial efficiency after 1200 h under ambient conditions. Notably, the CBD-based KCl modification offers both superior performance and simplified fabrication compared to conventional spin-coating methods, highlighting its potential for scalable and stable PSCs applications. A KCl-modified SnO 2 electron transport layer (ETL) was developed via a chemical bath deposition (CBD) strategy and integrated into carbon-electrode-based perovskite solar cells (PSCs). The incorporation of KCl effectively passivates oxygen vacancies and undercoordinated Sn 4+ defects in SnO 2 , thereby reducing defect density, facilitating interfacial charge extraction, and suppressing non-radiative recombination. The optimized device achieves a power conversion efficiency (PCE) of 15.13%, representing a 7.22% improvement over the control device, along with reduced hysteresis and enhanced moisture stability, retaining 74.2% of its initial efficiency after 1200 h under ambient conditions. Furthermore, the CBD approach offers simplified fabrication and reduced production costs compared to conventional spin-coating methods, demonstrating promising potential for scalable PSC applications. Download: Download high-res image (274KB) Download: Download full-size image