Fig. 9: Prospects for quasi-2D perovskite materials and devices.

a Schematic crystal structures of BAB-FAPbI₃ and PEA-FAPbI₃ quasi-2D perovskites. b Calculated binding energies of PbI₆-BAB, PbI₆-PEA, and PEA-PEA in quasi-2D perovskites. c Calculated molecular dissociation energy of the BAB- and PEA-based quasi-2D perovskites. d Schematic illustration of the self-trapped exciton emission process. e Normalized EQE depending on the 1- and 2-mm bending cycle of flexible quasi-2D PeLEDs doped with FPMAI. Inset: Digital photo of the working flexible quasi-2D PeLEDs doped with FPMAI. f Schematic of the amplified spontaneous emission process realized by population inversion in quasi-2D perovskites. Panels a–c are reprinted from ref. ¹⁶⁷ with permission from the AAAS. Panel d is reprinted from ref. ²⁰³ with permission from Springer Nature. Panel e is reprinted from ref. ¹⁸⁵ with permission from Wiley. Panel f is reprinted from ref. ¹⁸⁸ with permission from Wiley