Highly-efficient thermoelectric-driven light-emitting diodes based on colloidal quantum dots

Driven by sub-bandgap electric work and Peltier heat,thermoelectric-driven light-emitting diodes(TED-LEDs)not only offer much enhanced power-conversion-efficiency but also eliminate the waste heat generated during the operation of LEDs.However,costeffective and high-efficiency TED-LEDs are not readily accessible for the epitaxially grown III-V LEDs due to the high chip cost and efficiency droop at low-medium brightness(current densities).Here we show that electroluminescence of colloidal quantum dots(QDs)LEDs(QLEDs)circumvents the deficiencies faced by conventional LEDs.The optimal red-emitting device fabricated by cost-effective solution processing technics exhibits external-and internal-power-conversion-efficiency of 21.5%and 93.5%at 100 cd/m^(2),suited for high-efficiency solid-state lighting and high-resolution display.At this brightness,the electric driving voltage(V)of 1.89 V is lower than the photon voltage(Vp=hv/q=1.96 V,q being the elemental charge).With typical Vp=1.96 V,electroluminescence can be detected with the driving voltage as low as 1.0-1.2 V.Luminance of the thermoelectric-driven QLEDs(TED-QLEDs)remains ideally diffusion-dominated with the driving voltage lower than~1.5 V,and further improvement on charge transport is expected to extend the linear ideality to all practical driving voltages.