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Colloidal semiconductor nanocrystals for optoelectronic applications: photodetectors and light emitting diodes

Junling Qu 1
1 INSP-E6 - Physico-chimie et dynamique des surfaces
INSP - Institut des Nanosciences de Paris
Abstract : Nanocrystals with a dimension below their excitonic Bohr radius can provide size-tunable optoelectronic properties, enabling on-demand tailoring of properties for specific applications. Especially, the advance of wet chemistry synthesis of colloidal nanocrystals makes them promising building blocks for the next-generation solution-processible low-cost optoelectronics such as light emitting, sensing, and harvesting. My thesis targets two aspects of the nanocrystal-based devices: infrared (IR) photodetector and light emitting diode (LED). My thesis is first focused on the heavy-metal-free IR photodetection using the intraband transition of self-doped Ag2Se or the plasmonic resonance of remotely doped ITO (tin doped indium oxide) nanocrystals. Before integrating them to photoconductive devices, I study their optical and transport properties as well as their energy spectra. I then test their IR photodetection performance and rationalize their weak performance compared with their heavy metal counterparts. In the second part of my thesis, I advance to the all-solution nanocrystal-based LEDs in the visible and SWIR, with an emphasis on their practical applications. The designed visible LED using CdSe/CdZnS nanoplatelets (NPLs) shows the lowest turn-on voltage and the longest lifetime for NPL-based LED. I also provide insights on the origin of efficiency droop. Then, this LED is coupled with a homemade PbS broadband photodetector to achieve, for the first time, an all-nanocrystal based LiFi-like communication setup. For SWIR LEDs, HgTe is used as IR emitter. By forming a HgTe/ZnO bulk heterojunction in the emitting layer, a bright SWIR LED capable of active imaging is obtained.
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Submitted on : Saturday, May 8, 2021 - 10:08:54 AM
Last modification on : Tuesday, May 11, 2021 - 3:37:54 AM
Long-term archiving on: : Monday, August 9, 2021 - 6:03:05 PM


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  • HAL Id : tel-03221346, version 1


Junling Qu. Colloidal semiconductor nanocrystals for optoelectronic applications: photodetectors and light emitting diodes. Material chemistry. Sorbonne Université, 2021. English. ⟨tel-03221346⟩



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