Fabrication Of SnPc-based NIR Photosensitive Organic Field Effect Transistors And Study On Functional Layer Structures

Tin phthalocyanine?SnPc?is a kind of organic semiconductor material with excellent absorbing characteristic in near-infrared?NIR?region,and has been widely used into active layer of organic solar cells and other organic optoelectronic devices.However,due to its much lower mobility,it could hardly be applied into an organic field-effect transistor.In this dissertation,we mainly focused on the fabrication of SnPc-based NIR photosensitive organic field-effect transistors?PhOFETs?and investigation into the photoelectric performance of their different active layer structures.In the process,we also explained the design principle of functional layer structure of high-performance NIR PhOFETs.The main content can be divided into two parts:In part one,SnPc single layer PhOFET device was fabricated at first.The results indicate that SnPc single layer device shows a very poor performance as its mobility only takes a small value of¹0^-6 cm²V^-1s^-1.The next step is to fabricate a p-p active layer structure device by introducing a pentacene channel layer,whose mobility is much higher.We see a significant rise in mobility and photosensitive performance in this device.Photoresponsivity of 1.0×10³ mA/W was obtained when under illumination of48.8?W/cm² at the wavelength of 850 nm.The device with p-p-n active layer structure was also fabricated.The results indicate that the dark current was suppressed effectively and the exciton dissociation efficiency was enhanced significantly.The photoresponsivity of the device goes up to 2.68×10³ mA/W,the photosensitivity reaches a high value of 1.09×10⁴.In short,this device exhibits excellent NIR photosensitive performance.In the second part,starting from improving the photo-generated exciton dissociation efficiency,the photoelectric properties of the SnPc photoactive field-effect transistor after the introduction of bulk heterojunction were investigated.In the experiment,three PhOFET devices with different functional structures—a p-i structure of pentacene/SnPc:C₆₀,a p-i-n structure of pentacene/SnPc:C₆₀/C₆₀,and a p-p-i structure of pentacene/SnPc/SnPc:C₆₀ were fabricated.Due to the lack of SnPc photosensitive layer,the former two kinds of devices exhibited just moderate overall performance;while the device with p-p-i structure showed excellent photosensitive performance,whose photoresponsivity reached 1.89×10³ mA/W,and the maximum ratio of light to dark current is 5.93×10³.