Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5372950 | Chemical Physics | 2016 | 7 Pages |
â¢We study the photophysics of CdTe nanorods by ultrafast absorption spectroscopy.â¢We fit photobleaching and photoinduced absorption features at all time delays.â¢Dynamics are extracted from superpositions of bleaches (Gaussians) and derivatives.â¢Fast non-radiative recombination and slower hole trapping processes are extracted.â¢A potential approach to unveil ultrafast non-radiative recombination processes.
In transient absorption (TA) spectra, the bleach features originating from state filling are overlapped by their energy-shifted derivatives, arising from excited state energy level shifts. This makes the direct extraction of carrier dynamics from a single-wavelength time-trace misleading. Fitting TA spectra in time, as Gaussian functions and their derivative-like shifted Gaussians, allows to individually extract the real dynamics of both photobleached transitions, and their energy shifts. In CdTe nanorods (NRs) we found a delayed heating of holes due to the release of the large excess energy in the electron relaxation process. The slow hole-trapping process is consistent with a high number of surface trap states in these model NRs. Our results show that only a correct disentanglement of bleaching and energy shift contributions provides a reliable framework to extract the underlying carrier relaxation dynamics, including trapping, non-radiative recombination, and eventually carrier multiplication.
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