SnO 2 Interacted with Sodium Thiosulfate for Perovskite Solar Cells over 25% Efficiency.

Tin oxide (SnO 2 ) as electron transportation layer (ETL) has demonstrated remarkable performance applied in perovskite solar cells but still accommodated a host of defects such as oxygen vacancies, uncoordinated Sn 4+ , and absorbed hydroxyl groups. Here, we use inorganic sodium thiosulfate Na 2 S 2 O 3 to modify SnO 2 nanoparticles in a bulk blending manner. Strong interaction between Na 2 S 2 O 3 and SnO 2 occurs, as reflected from the elemental chemical state change. The interaction has endowed the SnO 2 film with better uniformity, increased conductivity, and more matched energy level with perovskite. Moreover, the modified SnO 2 film as a substrate could promote the crystallization of perovskite by suppressing unreacted residual PbI 2 . The trap density from perovskite bulk to the SnO 2 film across their interface has been effectively reduced, thus inhibiting the nonradiative recombination and promoting the transportation and extraction of charge carriers. Finally, the solar cell based on modified SnO 2 has achieved a champion efficiency of 25.2%, demonstrating the effectiveness and potential of sulfur-containing molecules on optimizing the SnO 2 property.