Novel optoelectronic devices based on planar graphene-nanotube hybrid film

Combining low-dimensional nanomaterials into hybrid nanostructures is a promising avenue to obtain enhanced material properties and to achieve nanodevices operating with novel principles. The family of carbon allotropes, with its rich chemistry and physics, attracts a great deal of attentions in forming novel hybrid nanostructures. In particular, the excellent electrical conductivities and large specific surface areas of 2D graphene and 1D carbon nanotubes (CNTs) have stimulated earlier theoretical and experimental investigations of 3D nanotube-graphene hybrid systems for hydrogen storage, supercapacitors and field-emitter devices. Both graphene and carbon nanotubes exhibit intriguing optical properties, such as broadband and tunable light absorption, which make them promising materials for photodetectors. We demonstrate a photoconductive gain of ∼105 electrons per photon in a carbon nanotube-graphene 1D-2D hybrid due to efficient photocarriers generation and transport within the nanostructure. A broadband photodetector (covering 400 nm to 1550 nm) based on such hybrid films is fabricated with a photoresponsivity of >100 A/W and a fast response time of ∼100 μs. The combination of ultra-broad bandwidth, high responsivity and fast operating speed affords new opportunities for facile and scalable fabrication of all-carbon optoelectronic devices. Charge transfer characterisitics of the all-carbon hybrid and demonstration of multi-functional devices will also be discussed.