Synthesis of Quinoxaline-Based Small Molecules Possessing Multiple Electron-Withdrawing Moieties for Photovoltaic Applications

Three quinoxaline-based small molecules possessing multiple electron-withdrawing moieties were synthesized by the Suzuki coupling reaction for organic photovoltaic cells (OPVs). The electron-donating triarylamine units were linked to both ends of electron-accepting 2,3-diphenyl quinoxaline (DPQ) derivatives with strong electron-withdrawing trifluoromethyl (CF 3 ) moieties to produce a reference D-A-D type small molecule of CF3Qx-0F . Furthermore, one and two fluorine atoms were additionally introduced to the 6,7-positions ofthe DPQ unit of CF3Qx-0F affording CF3Qx-1F and CF3Qx-2F , respectively. Owingto the significant contribution of the electron-withdrawing CF 3 and fluorine units, all inverted-type OPVs based on three small molecules exhibited high open circuit voltages greater than 0.82 V. In addition, the power conversion efficiencies (PCEs) of the devices were gradually improved with increasing number of fluorine atoms. The highest PCE (2.82%) with a V oc of 0.88 V, a short-circuit current of 6.38 mA cm −2 , and a fill factor of 50.6% was achieved from the device based on CF3Qx-2F .