| 초록 |
A new electron deficient unit, dialkyl-2H-benzimidazole, was synthesized and utilized for the syntheses of the conjugated polymers containing pairs of electron rich unit and electron deficient moiety for OPVs. This novel dialkyl-2H-benzimidazole unit is inducing more red-shift and provides higher solubility as compared to the BT unit of BT series, including PCDTBT. The thin film of PCDTMBI, with dimethyl-2H-benzimidazole unit, shows two broad absorption bands with maxima at 400 and 636 nm and an absorption onset of 756 nm, corresponding to a band gap of 1.64 eV. The oxidation onset of PCDTMBI was estimated to be 0.67 V, which corresponds to HOMO energy level of 5.47 eV. The LUMO energy level of the polymer was thus determined to be 3.82 eV. The device with PCDTMBI:PC71BM blend demonstrated a VOC value of 0.65 V, a JSC value of 10.0 mA/cm2, and a FF of 0.48, leading to the efficiency of 3.12%. |
