Novel 5‐(Benzo[b]thiophen‐3‐yl)pyridine‐3‐carbaldehyde (BTPA) Functionalization Framework For Modulating Fullerene Electronics

Through a cycloaddition reaction, fullerene (C(60)) was derivatized with a novel organic compound 5‐(benzo[b]thiophen‐3‐yl)pyridine‐3‐carbaldehyde to form the processable and stable 3‐(benzo[b]thiophene‐3yl)‐5‐fullero‐1‐methylpyrrolidinepyridine (BTFP) compound. BTFP exhibits close similarities to phenyl‐C61‐butyric‐acid‐methyl‐ester (PCBM) in terms of first reduction potential values (−0.62 and −0.61 V vs. Ag/AgCl, for BTFP and PCBM, respectively) and lowest occupied molecular orbital (LUMO) energy level values (3.93 eV in both cases). In chloroform, BTFP exhibits a bathochromic shift in the λ (max) of BTFP (λ (max,)BTFP=290 nm and λ (max,)PCBM=260 nm), owing to the grafted benzo[b]thiophene‐3‐yl)pyridine moiety. Despite the similarity in LUMO (3.93 eV) energy values, BTFP and PCBM differ in their luminescence‐quenching ability. The bathochromic shift in the λ (max) of BTFP (relative to PCMB) is likely to contribute to improved light absorption of a suitable donor for photovoltaic applications.