• • AB epoxy encapsulation induces transparency in Cs0.3MA0.7PbBr3 films via Lewis acid-base coordination, with FTIR redshift of C–O–C stretch from 1035.56 to 1018.05 cm−1 (Δν ≈ 17.5 cm−1), confirming Pb2+–ether interaction.
• • XPS analysis reveals Pb 4f binding energy shift of 0.25 eV and Br 3d5/2 shift of 0.45 eV, indicating electron donation and partial Br consumption, which modifies the perovskite electronic environment.
• • Grain refinement to tens of nanometers triggers a Mie-to-Rayleigh scattering transition, enhancing optical transmittance while maintaining green emission.
• • Encapsulated PeLEDs achieve a maximum luminance of 12,643 cd/m2 and a breakdown voltage of 27 V, demonstrating improved operational stability without compromising brightness.