High Efficiency Graphene Photoelectric And Thermoelectric Devices

The preparation,performance control and device design of new two-dimensional materials are hot topics in the field of nanomaterials.And the research of graphene in microelectronics and optoelectronic devices has been widely concerned.However,the disadvantages of the single two-dimensional material limit its application in microelectronics and optoelectronic devices.Therefore,the two-dimensional material composite and heterostructure system is the key path to realize high efficient two-dimensional material devices.For example,the zero band gap of graphene limits its application in photoelectric devices,but low self-absorption light-emitting diodes can be realized by utilizing the shallow junction characteristics of graphene/bulk semiconductor heterojunction.The high thermal conductivity of graphene limits its application in thermoelectric devices,but high power factor thermoelectric devices can be realized by doped graphene assembled films.Moreover,the graphene heterojunction sturcture has a high degree of flexibility in the design of electronic devices,which can realize more novel device structures.According to the shallow junction characteristics of graphene/3D semiconductor heterojunction,this paper fabriacted graphene/aluminum gallium nitride/gallium nitride double-color light-emitting diodes with high external quantum efficiency by introducing the tunneling mechanism.In this paper,a large area graphene thermoelectric film doped with strong acid and weak base salt is proposed according to the the highly adjustable Fermi level of graphene.The specific works of this paper are listed as follows:(1)Monolayer graphene was prepared by chemical vapor deposition and liquid phase method.(2)The tunneling mechanism of gallium nitride and the electron blocking effect of the surface grown alumina layer were investigated,which greatly improved the external quantum efficiency of the device.(3)The graphene thermoelectric film was assembly prepared by aqueous dispersions graphene layer.The the Seebeck coefficient and conductivity of graphene film was improved by doping with strong acid and weak base salt which was used to adjust the carrier concentration of graphene,so as to improve the power factor.Finally a graphene film with power factor of 8.4 ?W cm-1 K-2 at room temperature was realized.