Research Of Photoresponsive Organic Field-effect Transistors Photocurrent Model

Photoresponsive organic field-effect transistors (photOFETs)as an important part of organic field-effect transistors(OFETs)which can turn optical signals to electrical signals and can be widely used in photosensitive sensors and photosensitive imagiing and other fields.At present,the physical models of photOFETs are not sufficient,so this work is focusing on the single lead phthalocyanine(PbPc)and titanyl-phthalocyanine(TiOPc)photOFETs and then carried out research on the establishment and application of the physical model,the main work and conclusions are as follows:The bottom-gate top-contact geometry of single layer PbPc PhotOFET and TiOPc PhotOFET were tested under the wavelength of 808 nm at different gate voltages.The electrical characteristic were analyzed.Besides,the relationship between the photocurrent and incident power was also analyzed.Based on the solar cells and phototransistors photocurrent moldel,the photOFET photocurrent model was presented in this paper.The methods of parameter extraction was improved and modified.Among the photocurrent model,there were two fitting parameters which could be obtained from the devices datas.Then,both PbPc PhotOFET and TiOPc PhotOFET were used to prove the validity of the modified model at different the gate voltages and different the incident light power.And the relationship between fitting parameters the dark current or gate voltage was analyzed.No matter what kind of photOFETs,PbPc or TiOPc,when the gate voltages arised over the threshold voltage,one fitting parameter kept stability.Another parameter with the inverse of the gate voltage presented linear relationship.According to this situation,we gave explicit expression to the gate voltage and fitting parameter.