Fig. 1. PeLEDs structure and operation mechanism diagram^[31]. (a) Inverted LED structure (n-i-p); (b) normal LED structure (p-i-n); (c) operation mechanism of the two structures

Fig. 2. Band gap width of quantum well increases with decrease of quantum well thickness^[32]

Fig. 3. Energy-band alignment of methylammonium halide perovskites and various ETLs and HTLs^[35]

Fig. 4. Temperature-dependent PL and FWHM of MAPbBr₃ in amorphous nanoparticles and polycrystalline film^[38]. (a) PL spectral intensity; (b) FWHM

Fig. 5. Fabrication process of devices with submicron structure in the perovskite layer ^[14]

Fig. 6. EQE and current efficiency curves of NiO_x, NiO_x-PSSNa, and NiO_x-PSSNa-KBr PeLEDs^[51]. (a) EQE; (b) current efficiency

Fig. 7. Temperature-dependent (BA)₂CsPb₂Br₇ single crystal structure evolution^[60]

Fig. 8. Schematic illustration of fabrication process for 2D tin-based perovskite thin films^[88]

Fig. 9. Schematic diagrams of PeLEDs with dual functions of luminescence and light detection^[97]