Chlorobenzenesulfonic Potassium Salts as the Efficient Multifunctional Passivator for the Buried Interface in Regular Perovskite Solar Cells

The interfacial properties for the buried junctions of the perovskite solar cells (PSCs) play a crucial role for the further enhancement of the power conversion efficiency (PCE) and stability of devices. Delicate manipulation of the interface properties such as the defect density, energy alignment, perovskite film quality, etc., guarantees efficient extraction and transport of photogenerated carriers. Herein, chlorobenzenesulfonic potassium salts are presented as a novel multifunctional agent to modify the buried tin oxide (SnO2)/perovskite interface for regular PSCs. The increasing number of carbon-chlorine bonds (C-Cl) in 2,4,5-trichlorobenzenesulfonic potassium (3Cl-BSAK) exhibit efficient interaction with uncoordinated Sn, effectively filling oxygen vacancies in the SnO2 surface. Importantly, synergistic effects of the functional group-rich organic anions and the potassium ion are achieved for reduced defect density, carrier recombination, and hysteresis. A champion PCE of 24.27% and the open-circuit voltage (V-OC) up to 1.191 V for modified devices are obtained. The unencapsulated devices maintain 80% of their initial PCE after aging at 80 degrees C for 800 h in the atmosphere and 95% after aging for 100 d. With 3Cl-BSAK decoration, a high efficiency semitransparent PSC with a PCE of 12.83% and an average visible light transmittance (AVT) over 27% is also obtained.

Automated summary

This study presents a novel agent for modifying the interface properties of perovskite solar cells, resulting in improved efficiency and stability. The agent interacts with the surface of SnO2, filling oxygen vacancies and reducing defect density. The modified devices exhibit efficient charge extraction and transport, leading to high conversion efficiency and stability.