The hybrid device features an active colloidal quantum dot photodiode with a graphene phototransistor. By including an ‘active’ quantum dot photodiode, the team could increase charge collection in a highly absorbing thick quantum dot film. This, in turn, increased quantum efficiency, as well as the photoresponse.
The active quantum dot layer is said to allow more effective charge collection by exploiting carrier drift towards the graphene layer instead of relying only on diffusion. The researchers then combined this scheme with a graphene transistor to register high gains and gain-bandwidth products.
According to the team, their works shows this hybrid architecture demonstrates the potential of graphene and active quantum dot materials, opening new pathways for their integration in other optoelectronic materials in search for much higher performance and broader functionality.