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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, cost-effective 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/m2, 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.

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Publication history

Received: 17 August 2022
Accepted: 22 August 2022
Published: 26 August 2022
Issue date: October 2022

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© Tsinghua University Press 2022

Acknowledgements

Acknowledgements

We thank Dr. Yunzhou Deng and Prof. Dr. Yizhen Jin for helpful discussions. We thank Dr. Jiongzhao Li and Ms. Linxi Wang for preparing TEM and time-resolved PL data. We also thank Prof. Dr. Dawei Di for instructive advice on low-voltage characterization of QLED device. This work was financially supported by the National Natural Science Foundation of China (No. 62035013) and the Key Research and Development Program of Zhejiang Province (No. 2020C01001).

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Email: nanores@tup.tsinghua.edu.cn

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