A density functional theory study on the hole transfer in fullerene hydride C60H2

As a novel and convenient method for modifying the hole-transport property of fullerene C-60 materials, its hydrogenation, which gives C60H2, was considered. Firstly, for the analysis of the carrier-transfer mechanism between C60H2 Molecules, the geometrical difference between C60H2 and C60H2+, the natural population analysis (NPA) charge, and the electron spin resonance (ESR) parameters Of C60H2+ were calculated by density functional theory [B3LYP/6-311G(d)]. Secondly, the reorganization energies (lambda) of eleven isomers Of C60H2 with a small heat of formation Delta H-f degrees were calculated and compared with that Of C-60. It was shown that the magnitude of lambda Of C60H2 isomers is closely related to the geometrical difference between C60H2 and C60H2+. On the basis of Marcus theory, a smaller A results in larger hole mobility. It was found that six isomers Of C60H2 have a smaller lambda than C-60 (169 meV). The smallest lambda Of C60H2 (102 meV), which is over 40% less than that Of C-60, belongs to isomer 2b. At 300 K, its hole-transfer rate constant (k(ht)) is about 2.5 times as large as that Of C-60. It is remarkable that two synthesized isomers, 0a and 2a, also have 20% smaller lambda than C-60, and the k(ht) of these isomers are about 1.5 times as large as that Of C-60. These results indicate that the hydrogenation Of C-60 is an effective method for modifying the hole-transport property, and some isomers of C60H2 have potential utility as hole-transport materials.