A side chain-modified quaterthiophene derivative for enhancing the performance of organic solar cell devices

A conjugated polymer donor material, poly(3,4′′′- di(decylthiophenyl)quaterthiophene) (PDTQT), featuring decylthiophenyl side chains on the polymer backbone, was introduced to reduce the crystallinity of poly(quaterthiophene) (PQT-C12) layers in organic photovoltaic cells. The resulting PDTQT:PC₇₁BM blend active layer formed a well-interpenetrated nanoscale morphology that increased the power conversion efficiency (PCE) relative to devices based on highly crystalline PQT-C12. Bulk heterojunction solar cells fabricated using the PDTQT:PC₇₁BM blend thin films yielded the best photovoltaic performances with a high short-circuit current density of 9.8 mA cm^-2, a high open-circuit voltage of 0.91 V, a fill factor of 0.36, and a high PCE of 3.2% under AM 1.5G illumination with an intensity of 100 mW cm^-2. Decylthiophenyl side chain substitution appeared to be an effective strategy for obtaining high organic photovoltaic cell device performances.