The Research Of Organic Optoelectronic Devices With Dielectric Effects

Organic optoelectronic devices have received much attention in recent years,mainly owing to their flexibility and ease of fabrication.However,poor charge carrier mobility of most organic materials and the strong binding energy of excitons pose significant design restrictions on such devices,which limit their steady-state photoconduction performance.Recently it has been shown that organic semiconductor/insulator interfaces can produce photocurrent transients,remarkably decreasing the influence of poor mobility and strong exciton binding energy.Especially,fast operation speed and a great freedom in device architecture can be achieved.Because organic optoelectronic materials have been widely used in the application of photovoltaic cells?field-effect transistors,organic light-emitting diodes and due to their advantages of low toxicity?Production of large area?easy processability and flexibility.However,organic materials usually have much lower mobility,which limited their applications in organic optoelectronic devices.Recently,some research works show that the performance of organic field-effect transistors(OFETs)can be tuned by using dielectric polarization.Despite significant progress for organic electronics have been achieved,the underlying physics within organic devices is poorly understood,because of the formation of charge-transfer excitons?hopping-type carrier transport and interface dipoles at organic interfaces.Meanwhile,it is not applicable to accurately describe and predict the interfacial electronic structures and energy level alignment with conventional models in organic semiconductors,hindering the improvement of the performance of organic devices.In this paper,the effects of organic insulating dielectric layers on organic optoelectronic devices were studied,which may be helpful for organic photoelectric sensors and phototransistors.It has been shown that the photocurrent transients can be generated by ultrathin interfaces of organic semiconductor/blocking layers,and are tunable through the nature of the blocking layers.In addition,the polarity of the response can also be tuned by changing the thickness of the semiconductor layer or by using ferroelectric polymers as the blocking layer.It is notable that an organic semiconductor/liquid interface can produce very large photocurrent transients and provide freedom for device structure design for diverse applications due to the electric double layer effect.