Fabrication And Performance Modulation Of Memristor And Photodetector Based On Organic Materials

In recent years,the emergence of new materials with various structures and functions has been rapidly developed,among which organic materials has been made significant progress.Organic materials have many advantages,such as widely variety,simple preparation process,low cost and flexibility.The functional thin films based on organic materials have be used in the fields of photoluminescence information transmission,memory storage,photoelectric detection.In this paper,we mainly study the applications of memristor and photodetector employing two different organic materials.According to the characteristics and applications of organic materials,the main research content of this paper is divided into following two parts:The first part is the study on memristive properties of ferroelectric copolymer P(VDF-Tr FE).We prepared the memristor of sandwich structure by employing the ferroelectric copolymer P(VDF-Tr FE).The device exhibits great bipolar resistance switching characteristics.The low on-off voltage(3/-2.7 V)and high I_on/I_offratio(?10³)as well as fast switching speed are obtained in our device.Based on the intrinsic spontaneous polarization characteristics of ferroelectric materials,the conduction mechanism model of ferroelectric film conductive channel is established and the linear relationship between conductivity and average polarization intensity is given.The calculated results of conductance-voltage(G-V)curve show an obvious hysteresis phenomenon and the distinguishable high/low conductivity states.Our physical model is consistent with our experimental results,indicating a reasonable conduction mechanism of the device.The second part is the study on optoelectronic properties based on graphene/BUBD-1organic heterostructures.Using graphene as a growth substrate,highly ordered BUBD-1molecular packing is directly assembled employing the conventional thermal evaporation.We demonstrate a broadband phototransistor covering the UV-visible range(375-658 nm)based on self-assembled graphene/BUBD-1 organic heterostructure.Efficient interfacial charge transfer,strong light-matter interaction as well as long-lived trap states in organic molecular enable a high responsivity of 10⁶A/W.The rise time of the hybrid device is reasonably fast(?5 ms),while is benefit from fast interfacial charge transfer.The slow decay time(?500 ms)can be attributed to electron traps with different trap depths since they have longer charge release time in organic materials and thus result in a slower response speed.