Minimizing voltage loss for perovskite solar cells via synergistically passivating defects and reinforcing interfacial electric field

Perovskite solar cells have attracted much attention because of their excellent photoelectric properties. However, non-radiative recombination losses due to interface defects limit the open circuit voltage (Voc) of PSCs, which prevents further improvement in power conversion efficiency (PCE). To solve this problem, we introduced Li2SO4 into the SnO2/perovskite interface to obtain a higher Voc through interfacial passivation and enhancement of the interface electric field. Herein, Li+ presents bottom-up diffusion into perovskite surface, and forms dipoles with FA to enhance the interface electric field. Furthermore, SO in SO42- passivates Sn4+ on the surface of SnO2 and Pb2+ at the buried interface of perovskite. This method combines interfacial passivation with synchronous electric field enhancement, which promotes interfacial carrier migration and reduces non-radiative recombination and voltage loss (Vloss) at the interface. As a result, the SLS-device exhibits an enhanced Voc of 1.25 V, with a very low Vloss of 0.33 V, achieving an outstanding PCE of 24.31 %. Moreover, the device maintained 90 % of the initial PCE after exposure to ambient air for 1000 h. This work demonstrates the necessity to co-design the interface microstructure and electric field distribution for reducing the energy loss of perovskite photovoltaic devices and promoting the efficiency of interfacial charge transport. [Display omitted] •A synchronous electric field enhancement strategy has been proposed for PSCs.•[Li-FA]+ dipoles were generated at interface to boost charge transfer.•A very low Vloss of 0.33 V was achieved for PSCs.•High Voc of 1.25 V and 97 % of the S-Q limit of PSCs were reached.