Revealing hole trapping in zinc oxide nanoparticles by time-resolved X-ray spectroscopy

• DOI: 10.1038/s41467-018-02870-4
• Publication Date: 2018-01-29T21:20:16Z
• Authors: Thomas J. Penfold; Jakub Szlachetko; Fabio G. Santomauro; Alexander Britz; Wojciech Gawelda; Gilles Doumy; Anne Marie March; Stephen H. Southw...; Jochen Rittmann; Rafael Abela; Majed Chergui; Christopher J. Milne
• Keywords: Photoexcitation; Charge carrier; X-Ray Spectroscopy

Nanostructures of transition metal oxides, such as zinc oxide, have attracted considerable interest for solar-energy conversion and photocatalysis. Both applications are sensitive to the transport trapping photoexcited charge carriers. The probing electron has recently become possible using time-resolved element-sensitive methods, X-ray spectroscopy. However, valence-band-trapped holes so far escaped observation. Herein we use absorption spectroscopy combined with a dispersive emission spectrometer probe carrier relaxation processes in oxide nanoparticles after above band-gap photoexcitation. Our results, supported by simulations, demonstrate that within 80 ps, trapped at singly charged oxygen vacancies, which causes an outward displacement ~15% four surrounding atoms away from doubly vacancy. This identification hole traps provides insight future developments oxide-based nanodevices.