Semiconducting single-walled carbon nanotubes (s-SWCNTs) have attracted significant attention as a photoactive component in thin film photovoltaic solar cells and photodetectors due to their strong optical absorptivity and high charge transport mobility. However, the external quantum efficiency (QE) of s-SWCNT/acceptor heterojunction solar cells has been limited by poor exciton harvesting efficiency. Exciton trapping and quenching at defects are one suspected source of loss. Our aim is to study the influence of defects on bilayer s-SWCNT/C60 planar heterojunction photovoltaic devices via both experiments and modeling. First, diazonium chemistry is used to introduce covalent sp3 sidewall defects to s-SWCNTs at various densities. s-SWCNT/C60 heterojunction photovoltaic cells are then fabricated and a significant decrease in peak external QE is observed with increasing defect density. Second, we develop a diffusion limited contact quenching Monte Carlo model to assess the contributions of exciton quenching defects on exciton migration in bilayer s-SWCNT/C60 heterojunction devices. The model indicates that current state-of-the-art s-SWCNT-based devices are defect-limited and suggests that significant gains in exciton harvesting efficiency could be realized if more pristine, longer s-SWCNTs were utilized.

Three-dimensional structures of graphene have attracted extensive interest for their practical applications, such as supercapacitors and catalyst supports. Self-assembly is a typical technique to fabricate macroscopic graphene materials that can integrate with various superior properties. We exploited an efficient and environment-friendly approach to synthesize three-dimensional graphene under a mild condition. This proposed method was based on the chemical reduction of graphene oxide with the aid of different natural phenolic acids and in situ self-assembly of graphene sheets via π–π interactions. The obtained monolithic graphene exhibited low density, super hydrophobicity, high porosity, excellent mechanical strength and electrical conductivity. Therefore, this multifunctional material can be used as adsorbents for removal of oils, organic solvents and dyes from contaminated water, as well as electrode materials for supercapacitors.

Carbon nanomaterials (multiwalled carbon nanotube, graphene, graphene oxide nanoribbon) have been widely used as nanofillers for polymer reinforcement due to their excellent mechanical properties. However, the poor dispersibility and weak interface interaction with the polymers still limited their mechanical reinforcement performance. We developed both covalent and noncovalent functionalization technique to modify the surface properties of above carbon nanomaterials. The resultant materials could be well-dispersed in a variety of solvents and polymer matrix. They also exhibited excellent mechanical reinforcement (tensile strengths and Young’s modulus) of the polymer composites which is due to the highly available interface area and strong interlocking force with the polymers.