Design Of Image Sensor Array Based On Organic Thin Film Transistor

Flexible electronic devices or stretchable electronic devices have attracted more and more attention in recent years.Organic Thin Film Transistor(OTFT)has extremely broad application prospects in this field.For example,it is used in display pixel drive units and various photoelectric sensors,and used in logic circuits composed of organic thin film transistors.Benefiting from the continuous improvement of material synthesis process and device preparation technology,OTFT has been successfully applied in the field of organic photoelectric image sensing.In this paper,an organic image sensor array is designed based on the OTFT device prepared with zinc phthalocyanine as the active layer material.In this paper,based on the test data of zinc phthalocyanine organic thin film phototransistors prepared by the research group,a series of processing and analysis of the data are carried out,and mathematical methods are used for interpolation analysis,and mathematical expressions satisfying the curve trend are derived,the equivalent models of transistors under dark and light conditions are established respectively.Among them,the equivalent model in the dark state can be represented by two nonlinear controlled sources.Under light conditions,organic thin film transistors have obvious photovoltaic response characteristics and photocurrent multiplication effects,so the current amplification factor needs to be considered when establishing the equivalent model,that is,the model requires three nonlinear controlled sources to represent.After the model is built,compare the simulation data with the test data to verify the accuracy of the model.On the basis of the above research,based on the established phototransistor equivalent model and starting from the principle of photoelectric image sensing,an organic image sensor array is designed.The design is divided into integrator circuit,array control module circuit,refer to the power supply module circuit and output buffer module circuit and other parts.The most important integrator circuit uses a buffered direct injection structure with a negative feedback structure.The designed organic phototransistor image sensor array adopts a row-by-row readout structure,and uses a ring counter structure to generate applicable row selection signals.The simulation verification results show that the power consumption of each integrator unit circuit is 2.25 u W,and the current range that can be integrated is 0 to 100 u A.The designed image sensor circuit can meet the design requirements of ultra-low power consumption,and can be used for imaging signal acquisition of organic thin film phototransistor image sensors.