ABSTRACT
Photoinduced energy conversion processes are at the center of many green and renewable energy technologies. Materials widely used for photo-energy conversion are classic semiconductors, especially those at the nanoscale, such as silicon nanoparticles, semiconductor quantum dots, or nanorods. Carbon nanotubes (CNTs) are also photoactive, with high optical absorption cross-sections, rich excited state properties, and efficient photoinduced charge-transfer processes. CNTs have unique cylindrical hollow structures of extremely large aspect ratios, and one may conceptually visualize their structures by taking single or multiple graphene sheets and rolling them into seamless tubes. CNTs were found to display both band-gap fluorescence and defect-derived photoluminescence emissions, which are obviously different in origin, but complementary in certain properties. Studies of photoinduced electron transfer processes of CNTs hybridized with electron-donating or other electron-accepting molecules have provided evidence for donor–acceptor interactions. The recent emergence of graphene nanosheets and related materials may offer other great opportunities for the development of carbon tube–sheet hybrid nanotechnologies.
