Large area deposition of graphene thin films by Langmuir-Blodgett assembly and their optoelectronic properties

A challenge in exploiting the electrical properties of graphene is the fabrication of large area thin films in a scalable and inexpensive manner. The lack of a reliable and simple graphite exfoliation procedure has hindered the possibility of making films starting from pure graphene. This paper presents a scalable manner to obtain films of pure graphene on virtually any substrate with reproducible nanometric control over the number of layers and their optical and electronic characteristics. The optoelectronic properties of the films are investigated for different lateral flake size distributions (from 50 nm - 2 ¿m). Characterization of the films are studied by Raman and X-ray photoelectron spectroscopies. Results show that the films with the largest average lateral size exhibit the best electronic properties. The films of 20 nm thickness display sheet resistance of 5 kOhm/sq and transmittance of 75% at wavelength of 550 nm and therefore conductivity of 100 S/cm.