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

Abstract

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 (FAPbI3‐based) perovskite film. The minority carrier lifetime in double‐side‐passivated perovskite is extended to 1.1 μs 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 0.38 V for 1.53 eV‐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.

Relation between Fluorescence Quantum Yield and Open‐Circuit Voltage in Complete Perovskite Solar Cells

“…The presence of excess PbI 2 at both interfaces in solar cells with a high QY, low PCE, and high δ V is confirmed by scanning electron microscopy (Figure S7, Supporting Information). In the corresponding microscope image, the bright regions stand for PbI 2 , as shown previously in other publications …”

Progress of Surface Science Studies on ABX3‐Based Metal Halide Perovskite Solar Cells

“…However, PbI 2 at the interface of MAPbI 3 /TiO 2 can enhance the interfacial electronic coupling 108c. The calculated results are also consistent with the experimental results . A few studies describe the atomic structures at perovskite/HTL interfaces based on DFT calculations 102a,b.…”

δ‐CsPbI3 Intermediate Phase Growth Assisted Sequential Deposition Boosts Stable and High‐Efficiency Triple Cation Perovskite Solar Cells

“…We measured forward scans of different devices, and computed the H ‐index by combining forward with reverse scans PCE value. From the calculation results, Decice‐2 which has the highest PCE shows a more apparent hysteresis compared with Decice‐1, this is because there are moderate residual PbI 2 in Decice‐1 that passivating the interface …”

“…The XRD patterns of corresponding perovskite samples are shown in Figure b. It can be seen that there are two benefits for perovskite crystal growth resulting from the formation of δ‐CsPbI 3 phase in PbI 2 layer: i) the pronounced PbI 2 peaks (at 12.6° and 38.6° denoted as solid rhombus) are evidently weakened, implying the formation of PbI 2 has been suppressed to an appropriate amount, which is necessary for passivating the defects and enhancing the charge transport of perovskite layer . ii) the CsPbI 3 ‐IPG assisted perovskite crystals achieve better [001] orientation than the Control samples, attributing to the incorporation of δ‐CsPbI 3 , which lowers the formation energy of perovskite phase and promotes the α‐phase crystal growth.…”