Synthesis of transfer-free graphene films on dielectric substrates with controllable thickness via an in-situ co-deposition method for electrochromic devices

The solutions and polymer supported materials in graphene transfer process would introduce lots of containments, defects and wrinkles, which weakens the performance of graphene. Herein, an in-situ co-deposition method is carried out to obtain transfer-free graphene films with controllable thickness on several dielectric substrates. The amorphous carbon (carbon source) and copper (catalyst) are co-deposited on dielectric substrates. Followed by an in-situ annealing process, the amorphous carbon is transformed to few-layer graphene. High co-deposition temperature could promote the decomposition of Cu(acac)₂ precursors, leading to the controllable thickness of amorphous carbon layer in Cu@C films. Finally, 3-, 5-, 8- and 10- layers graphene films with transmittance of up to 93.5% and square resistance of 0.8 kΩ·sq⁻¹ are obtained and a high-performance electrochromic device is fabricated using 3 layers graphene films as electrodes. The “color” and “bleach” time of the electrochromic device is 16.6 s and 6.8 s with the transmittance of 26.8% and 79.7% separately. This method paves an alternative way for the batch production of transfer-free graphene film as electrode materials.