Improving Thermal Stability of High-Efficiency Methylammonium-Free Perovskite Solar Cells via Chloride Additive...

Tin dioxide (SnO₂), in perovskite solar cells (PSCs), stands out as the material most suited to the electron transport layer (ETL), yielding advantages with regard to ease of preparation, high mobility, and favorable energy level alignment. Nonetheless, there is a chance that energy losses from defects in the SnO₂ and interface will result in a reduction in the V_oc. Consequently, optimizing the interfaces within solar cell devices is a key to augmenting both the efficiency and the stability of PSCs. Herein this present study, we introduced butylammonium chloride (BACl) into the SnO₂ ETL. The resulting optimized SnO₂ film mitigated interface defect density, thereby improving charge extraction. The robust bonding capability of negatively charged Cl^- ions facilitated their binding with noncoordinated Sn⁴⁺ ions, effectively passivating defects associated with oxygen vacancies and enhancing charge transport within the SnO₂ ETL. Concurrently, doped BA⁺ and Cl^- diffused into the perovskite lattice, fostering perovskite grain growth and reducing the defects in perovskite. In comparison to the control device, the V_oc saw a 70 mV increase, achieving a champion efficiency of 22.86%. Additionally, following 1000 h of ambient storage, the unencapsulated device based on SnO₂ preburied with BACl retained around 90% of its initial photovoltaic conversion efficiency.