Novel small oligothiophene molecules with phenylene and naphthalene cores as promising absorber materials for organic solar cells

New small molecules bearing either phenylene or naphthalene core in combination with thiophene and rhodanine periphery moieties were synthesized by the Stille cross-coupling reaction. Their evaluation for prototypes of organic solar cells showed that replacing phenylene moiety by the naphthalene one caused decrease in the HOMO energy, while the open-circuit voltage and fill factors of solar cells based on these materials were significantly improved to manifest maximum power conversion efficiencies to 5.3%.