Disulfidation Interfacial Engineering toward Stable, Lead-Immobilizable Perovskite Solar Cells

Despite the multifaceted advantages, perovskite solar cells (PSCs) still suffer from low-stability issues under oxygen or moisture, which are largely due to the weak bonding and surface defects. The resulting soft nature makes the perovskite interface fragile to attack from ambient oxygen and water. Here, we report a facial surface disulfidation process via a compatible organic dithiolate compound to inhibit defects on the surface and immobilize lead ions. It is confirmed that the dithiolate groups can form strong lead-sulfur (Pb-S) bonds and efficiently reduce nonradiative recombination. Additionally, the passivation process can cause a downshift in the energy bond, resulting in efficient hole extraction at the perovskite interface. As a result, the devices with the dithiolate-passivated perovskite films exhibit better power conversion efficiency than the control devices, mainly due to the enhanced open-circuit voltage. The strong Pb-S bond improves the device stability by over 85% of its initial efficiency after 2000 h. In addition, lead leakage from the device is substantially suppressed by the disulfidation surface passivation.