Beyond Thin Stacks: Physics, Materials, and Architectures of Thick Perovskite Light‐Emitting Diodes

Thick light-emitting diodes (LEDs)-here defined as devices in 100 nm to multiple micrometers-are emerging across perovskite platforms. Departing from thin stacks, thick architectures reshuffle optical modes, electrical fields, and recombination statistics. On the physics side, increased emitter-metal separation weakens plasmonic loss and strengthens photon recycling, enabling higher light outcoupling efficiency. Lower current density at the same luminance suppresses emission quenching and field-driven interfacial reactions, improving stability and mitigating efficiency roll-off. On the materials side, thicker, denser films move recombination away from trap-rich interfaces, dilute local defect influence, and are more tolerant of roughness and particulates. On the architecture side, thicker stacks unlock integration of optical and barrier layers while preserving charge balance via mobility/doping management. This review surveys recent advances in thick perovskite LEDs, organized around physics, materials, and architectures. It also identifies key challenges, including voltage rise with longer transport paths, reabsorption/waveguiding, and slow ionic redistribution, and outlines strategies using high-mobility or lightly doped transports, photon-conserving internal optics, ion-blocking interlayers, and robust encapsulation. Finally, it highlights application pathways in ultra-bright signage, printable large-area and flexible displays, and micro-pixel engines, charting a roadmap from laboratory prototypes to manufacturable thick perovskite LEDs.