Temperature dependence of thermophotonic energy transfer in intracavity structures

Electroluminescent cooling (ELC) of light–emitting diodes (LEDs) at high powers is yet to be demonstrated. Earlier studies of photoluminescent cooling (PLC) suggested that temperature strongly affects the light emission efficiency and therefore it is useful to explore the temperature range below room temperature (RT) where ELC might be easier to observe. With that purpose in mind, we electrically characterised three different sized (0.2, 0.5 and 1 mm diameter) double–diode structure (DDS) devices, consisting of a coupled LED and photodiode (PD), at temperatures ranging from 100 K to 325 K to investigate how the temperature affects the efficiency of the structures in practice. We found that, for the studied devices, the coupling quantum efficiency (CQE) as well as the overall efficiency indeed increase when temperature decreases and reach their highest values at temperatures below room temperature.