Reduced graphene oxide film comprising a stack of rGO layers and its applications

A process for the preparation of an electrically back-contacted conductive reduced graphene oxide (rGO) structure, said structure comprising:

• a reduced graphene oxide (rGO) film having a total thickness from 20 nm to 5 micrometers, wherein the rGO film comprises a stack of rGO layers comprising flakes, and wherein a distance between two consecutive rGO layers is from 0.2 to 0.7 nm, and
• an additional conductive support on which the rGO film is deposited, wherein back-contacted means that the rGO film is placed onto the additional conductive support, such that a lower surface of the film is in contact with one of the surfaces of the conductive support, and
• wherein the process for the preparation of the electrically back-contacted conductive reduced graphene oxide (rGO) structure comprises the following steps:
• i′) filtering a graphene oxide (GO) solution through a porous membrane thereby forming a GO film on the membrane top, wherein the graphene oxide (GO) solution is an aqueous solution, the concentration of graphene oxide (GO) in the solution is from 0.001 to 5 mg/mL, and the volume filtered is from 5 to 1000 mL;
• ii′) transferring the GO film from the membrane onto the additional conductive support, whereby the GO film is placed between the membrane at the top and the additional conductive layer at the bottom;
• iii′) removing the membrane, whereby the GO film remains attached onto the additional conductive support;
• and
• iv′) hydrothermally reducing the GO film to form a reduced GO material (rGO), at a temperature from 100 to 240° C., under a pressure from 105 to 4·108 Pa, for a time period from 1 min to 24 h, in the presence of water.