State-Selective Dynamics of TiO2 Charge-Carrier Trapping and Recombination.
J Phys Chem Lett
; 10(17): 5265-5270, 2019 Sep 05.
Article
en En
| MEDLINE
| ID: mdl-31434481
ABSTRACT
Time-resolved pump-probe photoemission spectroscopy has been used to study the dynamics of charge-carrier recombination and trapping on hydroxylated rutile TiO2(110). Two types of pump excitation were employed, one in the infrared (IR) (0.95 eV) and the other in the ultraviolet (UV) (3.5 eV) region. With IR excitation, electrons associated with defects are excited into the bottom of the conduction band from the polaronic states within the band gap, which are retrapped within 45 ± 10 fs. Under UV excitation, the electrons in these band-gap states (BGSs) and valence-band electrons are excited into the conduction band. In addition to the fast polaron trapping observed with IR excitation, we also observe a long lifetime (â¼1 ps) component for both the depletion of hot electrons at the bottom of the conduction band and the refilling of the BGS. This points to a BGS-mediated recombination process with a picosecond lifetime.
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1
Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
J Phys Chem Lett
Año:
2019
Tipo del documento:
Article
País de afiliación:
Reino Unido