Open AccessSteady-state and nanosecond time-resolved photoluminescence spectroscopies of aqueous CdTe quantum dots
Author(s) -
Wu Wen-Zhi,
Yan Yu-Xi,
Zheng Zhi-Ren,
Qinhan Jin,
Weilong Liu,
Jianping Zhang,
Yang Yan-Qiang,
Su Wen-Hui
Publication year - 2007
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.56.2926
Subject(s) - photoluminescence , materials science , luminescence , nanosecond , excitation , quantum dot , photoluminescence excitation , exciton , femtosecond , cadmium telluride photovoltaics , optoelectronics , laser , atomic physics , molecular physics , optics , chemistry , physics , condensed matter physics , quantum mechanics
We have used femtosecond laser pulse to investigate the steady-state and nanosecond time-resolved photoluminescence of aqueous CdTe quantum dots (QDs). Up-conversion luminescences of the CdTe QDs induced by two-photon excitation were observed. Compared with 400nm excitation, the peak wavelength of photoluminescence induced by 1208nm excitation was red-shifted about 28nm (88meV). The decay kinetics showed a fast and a slow decay component which can be assigned to band-edge excitonic state (3—5ns) and surface trapping state (30—50ns), respectively. Luminescence and up-conversion luminescence at room temperature showed similar decay kinetics. The relative change of photoluminescence intensity between excitonic and trapping state is responsible for the red shift of emission peak. It was found that the proportion of excitonic emission in whole luminescence at 400nm excitation is bigger than that of excitonic emission at 800nm excitation, so with increasing the wavelength of laser excitation steady state spectra have the red shift of emission peaks.