Researchers from theRadboud University, tf2 Devices, and Aalto University have developed improved back reflectors for thin-film GaAs-based LEDs. Their work targets higher external quantum efficiency, crucial for thermophotonic energy conversion and electroluminescent cooling. The study focused on GaAs/InGaP double heterojunction LEDs made by epitaxial lift-off. A textured omnidirectional reflector combining ZnS and Ag was tested. It achieved nearly double the efficiency of planar Ag reflectors and ten times that of substrate-based LEDs. Optical and electrical tests supported these results. Their Photon Dynamics model indicated further gains with a ZnSe dome and optimized dielectrics. The design is suitable for III-V optoelectronic devices, including LEDs, thermophotovoltaics, and ultra-thin solar cells.