Excess PbI2 is an important component in improving the efficiency of perovskite solar cells ( PSCs ). However, the random aggregation of PbI2 crystals seriously interferes with the carrier transport behavior and accelerates the degradation of the perovskite film. Recently, Liu Hongli of Tianjin University proposed an effective strategy for in-situ dispersion of excess PbI crystals through columnar liquid crystals ( T6TE ) .
Rapid self-assembly induced by intermolecular π–π interactions enables T6TE to form ordered columnar phases with “edge-on” orientation in perovskites. The columnar T6TE has the advantages of strong negative electrostatic potential and high steric hindrance, which can effectively disperse excess PbI crystals .
Furthermore, T6TE significantly hinders the degradation of the perovskite film and the formation of Pb0 defects. The T6TE- assisted PSC achieved a power conversion efficiency ( PCE ) of 24.27% in hybrid Cs + -FA + -MA + perovskite . The PCE of large-area ( 1 cm 2 ) devices reaches 21.50% . After 1500 hours of storage in an atmosphere with a relative humidity of 40-60% , the unpackaged devices retained ≈ 85% of the initial PCE .
Huayu Bao et.al Columnar Liquid Crystal Enables In-Situ Dispersing of Excess PbI 2 Crystals for Efficient and Stable Perovskite Solar Cells Adv. Energy Mater. 2023
DOI: 10.1002/aenm.202303166