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Title: Ultrafast many-body bright–dark exciton transition in anatase TiO 2
The momentum-forbidden dark excitons can have a pivotal role in quantum information processing, Bose–Einstein condensation, and light-energy harvesting. Anatase TiO2with an indirect band gap is a prototypical platform to study bright to momentum-forbidden dark exciton transition. Here, we examine, by GW plus the real-time Bethe–Salpeter equation combined with the nonadiabatic molecular dynamics (GW + rtBSE-NAMD), the many-body transition that occurs within 100 fs from the optically excited bright to the strongly bound momentum-forbidden dark excitons in anatase TiO2. Comparing with the single-particle picture in which the exciton transition is considered to occur through electron–phonon scattering, within the GW + rtBSE-NAMD framework, the many-body electron–hole Coulomb interaction activates additional exciton relaxation channels to notably accelerate the exciton transition in competition with other radiative and nonradiative processes. The existence of dark excitons and ultrafast bright–dark exciton transitions sheds insights into applications of anatase TiO2in optoelectronic devices and light-energy harvesting as well as the formation process of dark excitons in semiconductors.  more » « less
Award ID(s):
2102601
PAR ID:
10537876
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
Proceedings of the National Academy of Science
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
120
Issue:
47
ISSN:
0027-8424
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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