Efficient photovoltaic conversion of graphene-carbon nanotube hybrid films grown from solid precursors

Large-area (e.g. centimeter size) graphene sheets are usually synthesized via pyrolysis of gaseous carbon precursors (e.g. methane) on metal substrates like Cu using chemical vapor deposition (CVD), but the presence of grain boundaries and the residual polymers during transfer deteriorates significantly the properties of theCVDgraphene. If carbon nanotubes (CNTs) can be covalently bonded to graphene, the hybrid system could possess excellent electrical conductivity, transparency and mechanical strength. In this work, conducting and transparentCNT-graphene hybrid films were synthesized by a facile solid precursor pyrolysis method. Furthermore, the synthesizedCNT-graphene hybrid films display enhanced photovoltaic conversion efficiency when compared to devices based on CNTmembranes or graphene sheets. Upon chemical doping, the graphene-CNT/Si solar cells reveal power conversion efficiencies up to 8.50%.