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Disentangling the evolution of electrons and holes in photoexcited ZnO nanoparticles

Lookup NU author(s): Dr Thomas PopeORCiD, Professor Thomas Penfold



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


The evolution of charge carriers in photoexcited room temperature ZnO nanoparticles in solution is investigated using ultrafast ultraviolet photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy, and ab initio molecular dynamics (MD) simulations. The photoluminescence is excited at 4.66 eV, well above the band edge, and shows that electron cooling in the conduction band and exciton formation occur in <500 fs, in excellent agreement with theoretical predictions. The x-ray absorption measurements, obtained upon excitation close to the band edge at 3.49 eV, are sensitive to the migration and trapping of holes. They reveal that the 2 ps transient largely reproduces the previously reported transient obtained at 100 ps time delay in synchrotron studies. In addition, the x-ray absorption signal is found to rise in ∼1.4 ps, which we attribute to the diffusion of holes through the lattice prior to their trapping at singly charged oxygen vacancies. Indeed, the MD simulations show that impulsive trapping of holes induces an ultrafast expansion of the cage of Zn atoms in <200 fs, followed by an oscillatory response at a frequency of ∼100 cm−1, which corresponds to a phonon mode of the system involving the Zn sub-lattice.

Publication metadata

Author(s): Milne CJ, Nagornova N, Pope T, Chen H-Y, Rossi T, Szlachetko J, Gawelda W, Britz A, van Driel T, Sala L, Ebner S, Katayama T, Southworth SH, Doumy G, March AM, Lehmann CS, Mucke M, Iablonskyi D, Kumagai Y, Knopp G, Motomura K, Togashi T, Owada S, Yabashi M, Nielsen MM, Pajek M, Ueda K, Abela R, Penfold TJ, Chergui M

Publication type: Article

Publication status: Published

Journal: Structural Dynamics

Year: 2023

Volume: 10

Online publication date: 03/11/2023

Acceptance date: 06/10/2023

Date deposited: 06/11/2023

ISSN (electronic): 2329-7778

Publisher: AIP Publishing LLC


DOI: 10.1063/4.0000204


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Funder referenceFunder name
Comunidad de Madrid and Universidad Autónoma de Madrid (Grant No. SI2/PBG/2020-00003)
IMDEA-Nanociencia (Grant No. CEX2020-001039-S)
JSPS KAKENHI (Grant Nos. JP21H04974)
JSPS KAKENHI (Grant Nos. JP19H05782)
JSPS KAKENHI (Grant Nos. JP21K18944)
Marie Heim-Vögtlin grant
National Science Centre in Poland (SONATA BIS 6 Grant No. 2016/22/E/ST4/00543)
Polish Ministry and Higher Education Project No. 1/SOL/2021/2
Spanish MIU (Grant No. BEAGAL18/00092)
Swiss SNF
Spanish MICIU (Grant No. PID2019-108678GB-I00)
U.S. Department of Energy Contract No. DE-AC02-06CH11357