Synthesis and Photovoltaic Properties of Copolymer Containing Fused Donor and Difluoroquinoxaline Moieties

Abstract

We report synthesis and photovoltaic properties of two new conjugated copolymers, PCPDTQxF and PDTSQxF, with 6,7-difluoro-2,3-dihexylquinoxaline unit prepared by Stille coupling reaction. The advantage of 6,7-difluoro-2,3-dihexylquinoxaline based copolymer are high PCEs due to lower HOMO energy level, long wavelength absorption and high hole mobility. The solid films of PCPDTQxF and PDTSQxF showed absorption bands with maximum peaks at about 623 and 493 nm and the absorption onsets at 711 and 635 nm, corresponding to band gaps of 1.74 and 1.95 eV, respectively. The oxidation onsets of the PCPDTQxF and PDTSQxF polymers were estimated to be 0.68 and 0.95 V, which correspond to HOMO energy levels of -5.48 and -5.75 eV, respectively. The PDTSQxF has lower HOMO energy level as compared to PCPDTQxF to lead higher V OC value. The device comprising PCPDTQxF:PCBM (1:2) dissolved to a concentration of 1 wt % in ODCB showed V OC value of 0.62 V, J SC value of 1.14 mA/cm 2 , and FF of 0.35, which yielded PCE of 0.25%.

TPD‐ and DPP‐based Small Molecule Donors Containing Pyridine End Groups for Organic Photovoltaic Cells

“…Organic photovoltaic cells (OPVs), which produce renewable energy, have drawn significant attention due to their low cost, ease of fabrication, light weight, and ability to obtain clean energy from sunlight . In the past decade, efforts have been dedicated to developing novel materials and new device manufacturing processes . Bulk heterojunction solar cells were commonly fabricated with the conventional structure, where the active layer is sandwiched between an indium–tin–oxide (ITO) anode and a low‐work‐function metal cathode (e.g., Al).…”