Comparative study on defect passivation of tin-based perovskite solar cells modified by phenylethylammonium salts (PEAX, X=Cl, I, Br)

Tin-based perovskite solar cells are a new type of photovoltaic technology. Tin-based perovskite solar cells use tin instead of traditional lead for the sake of environmental friendliness. Currently, the key challenges lie in solving the problems of low filling factor, low short-circuit current density, and low open-circuit voltage, which together lead to the overall performance decline in the cells. In this context, we conducted a detailed comparative analysis of the defect state passivation on the surface and interface of tin-based perovskite using phenethylammonium salts (PEAX, X = Cl, I, Br). The results show that doping PEAX in perovskite can improve the morphology, and hydrophobicity of the thin film. At the same time, the carrier recombination lifetime of the device modified by PEAX increases, and the carrier transport lifetime decreases. This indicates that the passivated device has a lower recombination rate and an increased charge transfer rate after illumination, thus reducing carrier recombination. In addition, the embedded electric field and composite resistance of the devices doped with PEAX are increased, and the density of defect states is decreased, which promotes carrier transfer, inhibits dark-state recombination, thereby improving the filling factor, short-circuit current density and open-circuit voltage of the device, and further improving the power conversion efficiency of the device. It is worth noting that among the three PEAX materials used for passivation, PEACl has the best passivation effect, and the highest efficiency of the device after PEACl passivation is 5.74 %. The study provides useful information on passivation methods for tin-based perovskite solar cells.