Experimental studies of the time-resolved bandgap emission of CdSe are used to probe the attributes required in a theoretical model for the carrier dynamics of semiconductor electrodes. By variation of excitation conditions and material properties, the validity of approximations in a commonly used model are tested. The experimental results show that the details of bulk recombination, the effects of self-absorption, and the influence of the space charge field are quite important factors for the carrier dynamics. Simulation results show that the detailed kinetics of the interfacial recombination can also have important consequences for the carrier relaxation. Appropriate modeling of these processes is needed before a surface recombination velocity can be extracted from such studies in a quantitative manner. htroduction Heterogeneous charge-transfer processes are ubiquitous in nature and crucially important in many technologies. Recom-
Time-resolved fluorescence is used to monitor the relaxation dynamics of minority carriers in n-type CdSe semiconductor electrodes. Five different silane compounds are used to chemically modify the interface and change the surface recombination velocity. In order to quantitate the interfacial recombination of charge carriers, a perturbative solution of a nonlinear diffusion equation is developed. These studies are combined with surface analysis and electrochemical studies to identify the nature of the chemically derivatized interface and characterize its electrical properties. This work clearly demonstrates the strong effects of surface treatment on the charge carrier dynamics and the sensitivity of fluorescence in monitoring the dynamics.
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