Localized Excitonic Electroluminescence from Carbon Nanodots
Guangsong Zheng1, Ting Wang2, Qing Lou1
1Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, China.
The Journal of Physical Chemistry Letters
|February 9, 2022
Summary
Localized excitons in carbon nanodots (CDs) enable efficient electroluminescence in new CD-based light-emitting diodes (LEDs). This breakthrough achieves low driving voltage and high quantum yield for advanced LED development.
Area of Science:
- Materials Science
- Optoelectronics
- Nanotechnology
Background:
- Localized excitons are key for high-performance electroluminescence in light-emitting diodes (LEDs).
- Carbon nanodot (CD) based LEDs have utilized electron-hole recombination, but localized excitonic electroluminescence was previously unreported.
Purpose of the Study:
- To fabricate and characterize localized excitonic electroluminescent devices using fluorescent carbon nanodots (CDs).
- To investigate the potential of localized excitons for advancing CD-based LED technology.
Main Methods:
- Fabrication of electroluminescent devices with fluorescent CDs as the active layer.
- Characterization of emission properties, including fluorescence quantum yield and Stokes shift.
- Measurement of device performance, such as turn-on voltage and luminance.
Main Results:
- Demonstrated strong localized excitonic yellow emission from CDs with a 76% fluorescence quantum yield and 2.1 eV Stokes shift.
- Achieved a sub-bandgap turn-on voltage of 2.4 V and a maximum luminance of 60.2 cd m⁻².
- Observed effective carrier trapping by localized centers, leading to sub-bandgap light emission.
Conclusions:
- Localized excitons are successfully implemented in CD-based LEDs, showing promising electroluminescent properties.
- The developed devices exhibit the lowest driving voltage among reported CD-based electroluminescent devices.
- Localized excitons offer a viable pathway for enhancing the performance and development of carbon nanodot LEDs.
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