Enhancing efficiency and stability in carbon-based perovskite solar cells through dual-interface modification

Carbon-based perovskite solar cells (C-PSCs) hold significant promise for enhancing the long-term stability and commercial viability of perovskite solar cells (PSCs). However, the power conversion efficiency (PCE) of C-PSCs is limited by excessive charge carrier recombination, which arises from defects within the perovskite material as well as at the interfaces between the perovskite and charge transport layers (CTLs). This study reports a dualinterface modification (DIM) technique aimed at reducing trap-state densities and interstitial defects at the tin dioxide (SnO2)/perovskite interface while simultaneously enhancing interfacial quality and crystallinity within the perovskite layer. SnO2 incorporated with agmatine sulfate (AGTS) as the electron transport layer (ETL) along with benzyl dimethyl hexadecyl ammonium chloride (HDBAC) to passivate the perovskite surface. This dualinterface modification (DIM) of the SnO2/perovskite interface has demonstrated a reduction in the number of interstitial defects and trap-state densities, while enhancements within the perovskite layer itself have led to improved crystallinity and notable improvements in light absorption properties. The DIM-modified C-PSCs achieve a PCE of 16.09 %, representing a significant enhancement of 32.10 % compared to a PCE of 12.18 % for the pristine device. Furthermore, the DIM-treated PSC retains 90 % of its initial PCE after 31 days at room temperature and ambient humidity.