Open AccessInfluence of Crystal Structure, Encapsulation, and Annealing on Photochromism in Nd Oxyhydride Thin Films
Author(s) -
Diana Chaykina,
F. Nafezarefi,
Giorgio Colombi,
S. Cornelius,
Lars J. Bannenberg,
Herman Schreuders,
B. Dam
Publication year - 2022
Publication title -
the journal of physical chemistry c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 289
eISSN - 1932-7455
pISSN - 1932-7447
DOI - 10.1021/acs.jpcc.1c10521
Subject(s) - photochromism , annealing (glass) , thin film , materials science , kinetics , chemical engineering , crystal structure , coating , partial pressure , photochemistry , nanotechnology , chemistry , crystallography , oxygen , composite material , organic chemistry , physics , quantum mechanics , engineering
Thin films of rare earth metal oxyhydrides show a photochromic effect, the precise mechanism of which is yet unknown. Here, we made thin films of NdH 3-2 x O x and show that we can change the band gap, crystal structure, and photochromic contrast by tuning the composition (O 2- :H - ) via the sputtering deposition pressure. To protect these films from rapid oxidation, we add a thin ALD coating of Al 2 O 3 , which increases the lifetime of the films from 1 day to several months. Encapsulation of the films also influences photochromic bleaching, changing the time dependency from first-order kinetics. As well, the partial annealing which occurs during the ALD process results in a dramatically slower bleaching speed, revealing the importance of defects for the reversibility (bleaching speed) of photochromism.
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