ausblenden:
Schlagwörter:
ABO(3) perovskites; polarons; optical properties
Zusammenfassung:
Time-resolved absorption and luminescence spectra have been measured in
KNbO3 perovskite crystals after pulsed band-gap excitation by 200 fs
laser pulses and 10 ns electron pulses. Quantum chemical calculations
using the large unit cell periodic model support the interpretation of
the observed transient absorption bands at 0.8 and 1.1 eV as the
self-trapped electron polarons and bound hole polarons, respectively.
The activation energy for the 2.2 eV green luminescence quenching is
0.05 eV. We suggest that the short lifetime (< 15 ns) of the
luminescence at RT is caused by the radiative recombination of nearest
electron and hole polarons. (C) 2003 Elsevier Ltd. All rights reserved.
