Investigation of newly designed asymmetric chromophore in view of power conversion efficiency improvements for organic solar cells

Abstract

The organic chromophore of (D1-π-A-D2) type, (E)-4-(3,5-dimethoxystyryl)-7-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole, OMe-BBTz, was synthesized using 2,1,3-benzothiadiazole as an acceptor with dimethoxyphenyl and hexyl bithiophene as donor units for the fabrication of bulk-heterojunction organic solar cells (BHJ-OSCs). The synthesized OMe-BBTz chromophore was comprehensively analyzed through structural, thermal, electrochemical, and photovoltaic characterizations. Reasonable HOMO (−5.39 eV) and LUMO (−3.41 eV) energy levels along with the optical band gap of ~1.98 eV were observed. The power conversion efficiency (PCE) of ~3.53% with the short circuit current density (JSC) of ~8.71 mA/cm2 and the open-circuit voltage (VOC) of ~0.698 V were achieved by BHJ-OSCs with OMe-BBTz:PC61BM (1:3, w/w) active layer.