  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 $\sim$ 10$^5$ electrons per photon in a carbon
nanotube-graphene one dimensional-two dimensional 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 high photoresponsivity of more than 100 AW$^{-1}$ and a fast
response time of approximately 100 {\mu}s. 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.
