Polymer-coated graphene films as anti-reflective transparent electrodes for Schottky junction solar cells

The traditional fabrication of graphene-based devices requires polymer-assisted transfer of graphene and a removal procedure of polymer coatings. Here, we propose to turn this process on its head and demonstrate a novel strategy of polymer-coated graphene as an optically antireflective and transparent electrode used in a graphene/silicon (G/Si) solar cell. No additional polymer removal and antireflection coatings (e.g. TiO₂ colloids) are needed in our strategy. By engineering the thickness of polymer protective coatings, the light absorption and short-circuit current density of graphene solar cells can be greatly enhanced. We also showed that retaining the polymer coatings avoided the degradation of electrical conductivity of graphene films. With HNO₃ doping applied on PMMA-coated G/Si solar cells, the PCEs can reach up to 13.34%. The long-term stabilities of HNO₃ doped G/Si solar cells are also improved by using fluoropolymer (CYTOP) coatings on graphene. Our approach provides a novel fabrication method of transparent graphene electrodes for graphene-based optoelectronic devices with excellent light absorption.