Synthesis and electronic properties of regiochemically defined 1,4-addition bromophenyl-fullerene

The synthesis and electronic properties of regiochemically defined 1,4-addition bromophenyl-fullerene, 4-(4-bromophenyl)-1-butyl-1,4-dihydro[60]fullerene [C₆₀(Bu)PhBr], were presented. A novel synthetic strategy using palladium(0)-catalyzed monoaddition reaction was developed to synthesize C₆₀(Bu)PhBr with high yield (up to 88.5 % isolated yield) and high regioselectivity. Owing to the great change in electron structure, C₆₀(Bu)PhBr exhibited high solubility, improved UV-vis optical absorption (stronger than that of PC₆₁BM), and a narrow band gap of 1.46 eV. Significantly high electron mobility up to 0.27 cm² V⁻¹ s⁻¹ was achieved for C₆₀(Bu)PhBr-based solution processed n-channel thin-film transistors, implying this new fullerene derivative C₆₀(Bu)PhBr could be an effective and versatile organic semiconductor.