Investigation On The Photoelectrochemical Interfacial Reaction Kinetics With Scanning Electrochemical Microscopy

The charge transfer process occurs at photoelectrode/electrolyte interface of Dye/Quantum dots sensitized solar cells is a field worthy of extensive study topic, that includes the regeneration process of the photosensitizers, photoelectric catalyst, and the transfer behavior of photogenerated electron and hole at the interface of photoelectrode/electrolyte. These processes are the necessary steps for generating photocurrent based on photovoltaic devices, and they can paly a key role in improving the photoelectric conversion efficiency of device. Due to the reaction occurrs in these photoelectrochemical interface is a fast charge transfer process, some conventional research methods can not be able to monitor real time information under working condition. Because of the high time and spatial resolution, and sensitivity, scanning electrochemical microscopy is very suitable to detect the trace change of electrochemical active material or chemical group located at the micro-region. And scanning electrochemical microscopy has proven to be an effective method to study the interfacial charge transfer kinetics. This research thesis is about the investigation of photoelectrochemical interfacial reaction kinetics with scanning electrochemical microscopy, and the major innovations and conclusions are as follows:One work of this research thesis is to investigate the reaction kinetics at the photo-anode/electrolyte interlace towards n-type device with the feedback mode of scanning electrochemical microscopy. In this work, we have studied the influence of redox shuttles [Co(bpy)3]3+/[Co(bpy)3]2+, I3-/I-on the regeneration kinetics of C106TBA and LD14. In addition, we have investigated the back transfer ability of the photo-generated electrons at photo-anode/electrolyte interface with different redox electrolyte, this is very helpful for assessing the interfacial recombination behavior of the photogenerated charges. Finally, we have interpreted the essential rule for the effects of photoelectrochemical reaction kinetics on the n-type photovoltaic device properties.One work of this research thesis is to investigate the reaction kinetics at the photo-cathode/electrolyte interface towards p-type device with the feedback mode of scanning electrochemical microscopy. In this work, we have studied the influence of redox shuttles I2/T-, I3-/I-on the regeneration kinetics of P1. In addition, we have investigated the back transfer ability of the photo-generated holes at photo-cathode/electrolyte interface with different redox electrolyte, this is very helpful for assessing the interfacial recombination behavior of the photogenerated charges.One work of this research thesis is to investigate the quantum dots regeneration kinetics at the photo-anode/electrolyte interface towards device with the feedback mode of scanning electrochemical microscopy. In this work, we have studied the influence of redox shuttles T2/T-,[Co(bpy)3]3+/[Co(bpy)3]2+, I3-/I-and band structure of quantum dots on the regeneration kinetics of quantum dots CdSe and CdS. Finally, we have interpreted the essential rule for the effects of quantum dots regeneration kinetics on the photovoltaic device properties.One work of this research thesis is to investigate the interfacial reaction kinetics in photoelectrochemical water splitting that includes the regeneration kinetics of photoelectric catalyst and the photo-generated charges (electrons and holes) transfer properties at the photo-anode/electrolyte interface with the feedback mode of scanning electrochemical microscopy. The results reveal that the Mo element can significantly improved the transfer property of the photo-generated holes and suppress the transfer of photo-generated electrons at the photo-anode/electrolyte interface when doped into BiVO4. This is very helpful for improving the interface charges separation efficiency and leads to a better photoelectrochemical catalytic activity compared with the pristine BiVO4.