Slow Hot-Exciton Cooling and Enhanced Interparticle Excitonic Coupling in HgTe Quantum Dots

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

1 Scopus Citations
View graph of relations

Author(s)

  • Kezhou Fan
  • Aleksandr A. Sergeev
  • Lu Zhang
  • Christopher C. S. Chan
  • Stephen V. Kershaw
  • Junwei Liu
  • Kam Sing Wong

Detail(s)

Original languageEnglish
Pages (from-to)18011-18021
Journal / PublicationACS Nano
Volume18
Issue number27
Online published27 Jun 2024
Publication statusPublished - 9 Jul 2024

Abstract

Rapid hot-carrier/exciton cooling constitutes a major loss channel for photovoltaic efficiency. How to decelerate the hot-carrier/exciton relaxation remains a crux for achieving high-performance photovoltaic devices. Here, we demonstrate slow hot-exciton cooling that can be extended to hundreds of picoseconds in colloidal HgTe quantum dots (QDs). The energy loss rate is 1 order of magnitude smaller than bulk inorganic semiconductors, mediated by phonon bottleneck and interband biexciton Auger recombination (BAR) effects, which are both augmented at reduced QD sizes. The two effects are competitive with the emergence of multiple exciton generation. Intriguingly, BAR dominates even under low excitation fluences with a decrease in interparticle distance. Both experimental evidence and numerical evidence reveal that such efficient BAR derives from the tunneling-mediated interparticle excitonic coupling induced by wave function overlap between neighboring HgTe QDs in films. Thus, our study unveils the potential for realizing efficient hot-carrier/exciton solar cells based on HgTe QDs. Fundamentally, we reveal that the delocalized nature of quantum-confined wave function intensifies BAR. The interparticle excitonic coupling may cast light on the development of next-generation photoelectronic materials, which can retain the size-tunable confinement of colloidal semiconductor QDs while simultaneously maintaining high mobilities and conductivities typical for bulk semiconductor materials. © 2024 American Chemical Society.

Research Area(s)

  • biexciton Auger recombination, HgTe quantum dots, hot-exciton cooling, interparticle excitonic coupling, phonon bottleneck

Citation Format(s)

Slow Hot-Exciton Cooling and Enhanced Interparticle Excitonic Coupling in HgTe Quantum Dots. / Fan, Kezhou; Sergeeva, Kseniia A.; Sergeev, Aleksandr A. et al.
In: ACS Nano, Vol. 18, No. 27, 09.07.2024, p. 18011-18021.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review