Synthesis and applications of various optoelectronic materials based on fullerene and carborane derivatives

Abstract

This thesis deals with optoelectronic materials based on fullerene (C60) and carborane derivatives. Various optoelectronic materials were synthesized in the form of small molecular or polynorbornene-based materials or hybrids of fullerene and o-carborane derivatives. The prepared materials were utilized as electroactive materials in optoelectronic device applications such as OPVs, and OFETs or in the filed of chemosensor owing to their unique and superior electronic properties. Firstly, vinyl-addition homo- and co-polymerization of norbornene monomer (M1) functionalized with a [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) moiety using a Pd(II) catalyst in combination with a 1-octene chain transfer agent efficiently produced polynorbornenes with side-chain PCBM groups. While the homopolymer was insoluble in organic solvents, the copolymers containing 62 mol-% (P2) and 50 mol-% (P3) of the PCBM moiety were soluble in chlorinated solvents such as o-dichlorobenzene. The bulk-heterojunction organic photovoltaic devices fabricated based on the poly(3-hexylthiophene):P3 blends showed that P3 can adequately function as an electron acceptor, leading to a cell with a power conversion efficiency of 1.5%. Secondly, polynorbornenes with pendant PCBM moieties were produced by ring-opening metathesis polymerization (ROMP) of norbornene monomer functionalized with PCBM using a Grubbs second-generation catalyst. The resulting ROMP polymers (RP1 and RP2) are soluble in ODCB and CS2 at ambient temperature. RP1 possessed high decomposition temperature of 432 °C and moderate glass transition temperature of 127 °C, but was thermally cross-linked at 80 °C. While the bulk-heterojunction organic photovoltaic devices fabricated with the active layer comprising poly(3-hexylthiophene) (P3HT) donor and RP1 acceptor at ambient temperature exhibited a power conversion efficiency of 0.66%, the efficiency decreased to 0.28% after pre-annealing of the active layer at 110 °C. In contrast, t...