Planar carbon nanotube–graphene hybrid films for high-performance broadband photodetectors

Graphene has emerged as a promising material for photonic applications fuelled by its superior electronic and optical properties. However, the photoresponsivity is limited by the low absorption cross-section and ultrafast recombination rates of photoexcited carriers. Here we demonstrate a photoconductive gain of ∼10 5 electrons per photon in a carbon nanotube–graphene hybrid due to efficient photocarriers generation and transport within the nanostructure. A broadband photodetector (covering 400–1,550 nm) based on such hybrid films is fabricated with a high photoresponsivity of >100 A W −1 and a fast response time of ∼100 μs. The combination of ultra-broad bandwidth, high responsivities and fast operating speeds affords new opportunities for facile and scalable fabrication of all-carbon optoelectronic devices. Graphene has excellent electronic properties but its photoresponsivity is limited by low absorption and the ultrafast recombination of photoexcited carriers. Here, the authors demonstrate fast, high responsivity and broadband photodetectors by combining graphene with single-wall carbon nanotubes.