Fabrication Of The Green-light Photoresponsive Organic Field-effect Transistor Based On PTCDA

Organic semiconductor materials and photosensitive devices has been a hot area of research in recent years in the field of microelectronics.With numerous advantages such as flexibility,being able to be fabricated in large scale,simple procedure of preparation,Organic Field Effect Transistors?OFET?gained huge prospect and potentiality.As an important branch of OFET,Photosensitive Organic field effect transistor?photOFET?got widespread attention and research for its great potentiality in area of new photodetector.Among plenty of studies in photOFET,few works focused on green light sensitivity.Thus,the emphasis of this paper was put on fabrication and analysis of green light photosensitive photOFET device.PTCDA?3,4,9,10 perylenetertra-caboxylic dianhydride?is a typical kind of broadband gap photosensitive haplotype organic semiconductor materials,with absorption peak between 500 550 nm,which owns great sensitivity and good photoelectric property for in green light.In this paper,PTCDA was as unified green light sensitive material.Four kinds of green light photOFET with different structures were fabricated respectively,including single layer structure and heterojunction structure,considering the effect of light absorption,planar heterojunction was chosen in the second structure.Sketch of the four devices are as followed:The first device: N type monolayer PTCDA photOFET.Output characteristic presents typical n-type saturation output characteristic curve,but limited by low carrier mobility of PTCDA,therefore,the output current is very weak and the threshold voltage is too high for practical application.The second device: N type photOFET based on C60/PTCDA Planar heterojunction.Output characteristic presents typical N type output saturation characteristic curve,and the C60/PTCDA Planar heterojunction acts as the semiconductor layer,and the layer contain C60 is as electron transport layer.While the gate voltage is 50 V,saturation drain current is near 3000 nA,and the threshold voltage is-4.41 V,the saturation mobility reaches 0.78cm2/?V·s?,the maximum photoresponsivity is 815.98 and the maximum photosensitivity is 36.23mA/W.The third device : the TiOPc/PTCDA Planar heterojunction phototransistor of P type.farbication and characterization of TiOPc and TiOPc/PTCDA thin film based on Si/SiO₂ substrate.Under illumination condition,the saturation mobility was increased to 3.64×10-3cm2/?V·s?,the threshold voltage is reduced to-4.10 V,the maximum light to dark current ratio of the device is 31.00,the maximum photoresponsivity of the device is 2.27A/W.The fourth device: the planar heterojunction phototransistor of P type based on Pentacene/PTCDA.fabrication and characterization of Pentacene and Pentacene/PTCDA thin film.Compared with TiOPc/PTCDA phototransistor,the output current increases 62.60%,the maximum photosensitivity and photoresponsivity are 19.62A/W and 56.15 respectively,Photosensitive property and current/voltage characteristic are far better than the TiOPc/PTCDA device.Overall,the output current of N type organic Phototransistor based on C60/PTCDA is better than the structure of TiOPc/PTCDA or Pentacenene/PTCDA,but the photosensitivity is limited by the same type of heterojunction structure,the photoresponsivity is lower than the other two heterogeneous heterojunction devices.The performance of Pentacenene/PTCDA is better than the device of TiOPc/PTCDA structure,with better output characteristic and photosensitizing property.In this paper,to a certain extent,the process of four kinds of devices were optimized,meanwhile,we provide specific processes of four kinds of devices in detail.