Graphene–Carbon Nanotube Hybrid Films for High-performance Photovoltaic Devices

Abstract

In this work, perspectives of using mono- and bilayer graphene–carbon nanotube (CNT) hybrid films in optoelectronic and photovoltaic devices were investigated using in silico methods. The atomic structure of a graphene–CNT hybrid film is formed by graphene layers with nanotubes between them, which have sp3-hybridized atoms and form covalent bonds with graphene. Atomistic models of hybrid films with equilibrium configurations were obtained using an original technique called the magnifying glass method. For constructed models of mono- and bilayer hybrid films the density of electronic states (DOS) and the band structure were calculated by the self-consistent charge density functional tight-binding quantum (SCC DFTB) method. The relationship between the chirality of the nanotubes and the conductivity of a graphene–CNT hybrid film was established. The regularities of the current flow in graphene–CNT films were investigated using the apparatus of the Keldysh Green's functions and the Landauer–Buttiker formalism. The influence of the diameter of the tubes and the inter-tube distance on the resistance and static electrical conductivity of a graphene–CNT film was investigated. The coefficients of transmittance, reflection and absorption of two types of electromagnetic waves (H-wave and E-wave) for graphene–CNT films were calculated in the framework of Maxwell's classical theory of electromagnetism. The relationship between the transmittance coefficient and the surface resistance of a hybrid film was established.