This work is concentrated on elucidating the mechanism of the electric field enhanced water dissociation. A simple model was established for the theoretical current-voltage characteristics in water dissociation proces...This work is concentrated on elucidating the mechanism of the electric field enhanced water dissociation. A simple model was established for the theoretical current-voltage characteristics in water dissociation process on a bipolar membrane based on the existence of a depletion layer and Onsager's theory. Particular attention was given to the influence of applied voltage on depletion thickness and the dissociation constant. The factors on the water splitting process, such as water diffusivity, water content, ion exchange capacity, temperature, relative permittivity, etc. Were adequately analysed based on the derived model equations and several suggestions were proposed for decreasing the applied voltage in practical operation. The water dissociation tests were conducted and compared with both the theoretical calculation and the measured current-voltage curves reported in the literature, which showed a very good prediction to practical current-voltage behavior of a bipolar membrane at high current densities when the splitting of water actually commenced.展开更多
Dye-sensitized solar cell （DSSC） is one of the most rapidly developed solar cells in the past 20 years. Many characterization methods have been employed for further understanding the operational details of the photo...Dye-sensitized solar cell （DSSC） is one of the most rapidly developed solar cells in the past 20 years. Many characterization methods have been employed for further understanding the operational details of the photo- electric conversion in DSSC as well as the evaluation of cell performance. Electrochemical methods have become pow- erful tools for studying the charge transfer and interfacial process. In this review, we introduce and explain the various electrochemical methods used to characterize and analyze DSSC, including current-voltage （I-V） scan measurement, cyclic voltammetry, electrochemical impedance spec- troscopy, intensity-modulated photocurrent spectroscopy, and intensity-modulated photovoltage spectroscopy. In ad- dition, some applications were provided as samples to elucidate electron transfer kinetics, energy levels and electrocatalytic activity of the materials used in DSSC.展开更多
The conventional charge transport models based on density- and field-dependent mobility, only having a non-Arrhenius tem- perature dependence, cannot give good current-voltage characteristics of poly （2-methoxy-5-（2...The conventional charge transport models based on density- and field-dependent mobility, only having a non-Arrhenius tem- perature dependence, cannot give good current-voltage characteristics of poly （2-methoxy-5-（2＇-ethylhexyloxy）-p-phenylene vinylene） （MEH-PPV） hole-only devices. In this paper, we demonstrate that the current-voltage characteristics can give a good unified description of the temperature, carrier density mad electric field dependence of mobility based on both the Arrhenius temperature dependence and the non-Arrhenius temperature dependence. Fu^hermore, we perform a systematic study of charge transport and electrical properties for MEH-PPV. It is shown that the boundary carrier density has an important effect on the current-voltage characteristics. Too large or too small values of boundary carrier density will lead to incorrect cur- rent-voltage characteristics. The numerically calculated carrier density is a decreasing function of the distance to the interface, and the numerically calculated electric field is an increasing function of the distance. Both the maximum of carrier density and the minimum of electric field appear near the interface.展开更多
基金Supported by the National Natural Science Foundation of China (No. 29976040), the Natural Science Foundation of Anhui Province (No. 99045431) and Youth Foundation of USTC.
文摘This work is concentrated on elucidating the mechanism of the electric field enhanced water dissociation. A simple model was established for the theoretical current-voltage characteristics in water dissociation process on a bipolar membrane based on the existence of a depletion layer and Onsager's theory. Particular attention was given to the influence of applied voltage on depletion thickness and the dissociation constant. The factors on the water splitting process, such as water diffusivity, water content, ion exchange capacity, temperature, relative permittivity, etc. Were adequately analysed based on the derived model equations and several suggestions were proposed for decreasing the applied voltage in practical operation. The water dissociation tests were conducted and compared with both the theoretical calculation and the measured current-voltage curves reported in the literature, which showed a very good prediction to practical current-voltage behavior of a bipolar membrane at high current densities when the splitting of water actually commenced.
基金supported by the National Natural Science Foundation of China(51072170,21321062)the National Basic Research Program of China(2012CB932900)
文摘Dye-sensitized solar cell （DSSC） is one of the most rapidly developed solar cells in the past 20 years. Many characterization methods have been employed for further understanding the operational details of the photo- electric conversion in DSSC as well as the evaluation of cell performance. Electrochemical methods have become pow- erful tools for studying the charge transfer and interfacial process. In this review, we introduce and explain the various electrochemical methods used to characterize and analyze DSSC, including current-voltage （I-V） scan measurement, cyclic voltammetry, electrochemical impedance spec- troscopy, intensity-modulated photocurrent spectroscopy, and intensity-modulated photovoltage spectroscopy. In ad- dition, some applications were provided as samples to elucidate electron transfer kinetics, energy levels and electrocatalytic activity of the materials used in DSSC.
基金supported by the National Basic Research Program of China (Grant No.2007CB310407)Foundation for Innovative Research Groups of the NSFC (Grant No.61021061)+1 种基金the National Natural Science Foundation of China (Grant Nos.50972023 and 61071028)the International S&T Cooperation Program of China (Grant No.2006DFA53410)
文摘The conventional charge transport models based on density- and field-dependent mobility, only having a non-Arrhenius tem- perature dependence, cannot give good current-voltage characteristics of poly （2-methoxy-5-（2＇-ethylhexyloxy）-p-phenylene vinylene） （MEH-PPV） hole-only devices. In this paper, we demonstrate that the current-voltage characteristics can give a good unified description of the temperature, carrier density mad electric field dependence of mobility based on both the Arrhenius temperature dependence and the non-Arrhenius temperature dependence. Fu^hermore, we perform a systematic study of charge transport and electrical properties for MEH-PPV. It is shown that the boundary carrier density has an important effect on the current-voltage characteristics. Too large or too small values of boundary carrier density will lead to incorrect cur- rent-voltage characteristics. The numerically calculated carrier density is a decreasing function of the distance to the interface, and the numerically calculated electric field is an increasing function of the distance. Both the maximum of carrier density and the minimum of electric field appear near the interface.
