Fabrication And Performance Investigation Of The Novel Organic Phototransistors

Organic semiconductor materials have attracted considerable attentions in the field of electronics due to their advantages of flexibility,solution-processable,and potential applications in large area flexible electronic circuits.With a large number of high-performance organic semiconductor materials continue to emerge,as well as advances in device preparation technology,organic electronic devices began to develop towards diversify,multi-functional direction.In recent years,with the development of optoelectronic technology,mutil-functional organic semiconductor devices typified by phototransistors have become a hot spot in the field of organic electronics.In this paper,two different organic phototransistors with high photoresponse and wide spectral absorption are designed and fabricated,then their function and application are also studied and explored.The main results are shown as follows:1.The organic small molecule semiconductor material perylenediimide with strong molecular conjugate stacking are selected to prepare the nanowire solution by using the poor solvent growth method.The liquid-liquid interface interaction makes organic nanowires assemble into aligned nanowire films at the air/water(gas/liquid)interface.Then the supramolecular nanowire films are successfully transferred onto substrate to fabricate high photoresponsive phototransistor.In addition,the performance of the device performance is further optimized by means of interface modification,so that the maximum mobility of the field effect transistor based on the nanowire film active layer is as high as 4×10-4 cm2 V-1 s-1,exhibiting excellent charge transport properties.At the same time,PTCDI-C8 nanowire thin-film phototransistors exhibit high photoelectric response properties due to the ordered nanowire film morphology and good spectral absorption properties of the active layer material,and the maximum value of the photocurrent/dark current ratio is2.8×104,this method will find a new outlet for organic semiconductor materials.2.A new floating gate structure phototransistor is designed and constructed.This special structure selects organic bulk heterojunction as an isolated light-absorbing layer and n-type naphthalimide small molecule semiconductors as independent charge transport layers,respectively.By combining the excellent spectral absorption properties of organic heterojunction and excellent charge transport properties of the naphthalimide small molecule semiconductors,The floating gate phototransistor has a current variation of 300 n A under 32.4 ?W/cm2 light intensity,and the photoresponsivity is up to 4840 m A/W,showing ultra-sensitive photoresponse properties.In addition,the photoelectric response mechanism is investigated.And the effects of light absorption layer material,isolation layer material and film deposition methods on photoresponse properties of phototransistor are systematically investigated,which provide a new strategy for the construction of high-performance phototransistors.