Unraveling Exciton Trap Dynamics and Nonradiative Loss Pathways in Quantum Dots via Atomistic Simulations

Journal Article · Tue Aug 12 00:00:00 EDT 2025 · ACS Nano

DOI:https://doi.org/10.1021/acsnano.5c07897· OSTI ID:2587924

Hou, Bokang; Gatto, Salvatore; Rudge, Samuel L; Runeson, Johan E; Thoss, Michael; Rabani, Eran

Surface defects in colloidal quantum dots are a major source of nonradiative losses, yet the microscopic mechanisms underlying exciton trapping and recombination remain elusive. Here, we develop a model Hamiltonian based on atomistic electronic calculations to investigate exciton dynamics in CdSe/CdS core/shell QDs containing a single hole trap introduced by an unpassivated sulfur atom. By systematically varying the defect depth and reorganization energy, we uncover how defect-induced excitonic states mediate energy relaxation pathways. Our simulations reveal that a single localized defect can induce a rich spectrum of excitonic states, leading to multiple dynamical regimes, from slow, energetically off-resonant trapping to fast, cascaded relaxation through in-gap defect states. Crucially, we quantify how defect-induced polaron shifts and exciton-phonon couplings govern the balance between efficient radiative emission and rapid nonradiative decay. These insights clarify the microscopic origin of defect-assisted loss channels and suggest pathways for tailoring QD optoelectronic properties via surface and defect engineering.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: US Department of Energy; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Chemical Sciences, Geosciences & Biosciences Division (SC-22.1)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 2587924
• Journal Information: ACS Nano, Journal Name: ACS Nano Journal Issue: 31 Vol. 19
• Country of Publication: United States
• Language: English

Related Subjects

Defects
Energy
Excitons
Quantum dots
Recombination
exciton defect
exciton−phonon coupling
quantum dot
semiempirical pseudopotential
trapping dynamics