Double-Side-Passivated Perovskite Solar Cells with Ultra-low Potential Loss

An ideal crystal quality in the grain interior of perovskite polycrystalline films is well recognized; therefore, understanding interfacial impact and the ways to limit interfacial recombination is critical to fabricating highly efficient solar cells. In perovskite solar cells, PbI2 has been used to passivate defects at grain boundaries, yet a systematic PbI2 passivation engineering to boost the high-performance perovskite solar cells has not been fully explored. Here, a novel device structure comprised of double-side-passivated perovskite solar cells (DSPC) is devised through intentionally distributing PbI2 to both the front/rear-side surfaces and grain boundaries of the formamidinium-lead-iodide-based (FAPbI(3)-based) perovskite film. The minority carrier lifetime in double-side-passivated perovskite is extended to 1.1s with single-exponential decay using time-resolved photoluminescence. This result indicates a generic passivation effect of PbI2 on perovskite interfaces, resembling SiO2 passivation in silicon solar cells. Correspondingly, the best photovoltaic device with TiO2-based planar structure presents a stabilized efficiency of 22%. Moreover, DSPC effectively boosts the limits of open circuit voltages toward a record potential loss of 0.38V for 1.53eV-bandgap perovskites. The architecture of double-side-passivated perovskite opens up new opportunities to exceed the efficiency of state-of-the-art perovskite solar cells.