| 초록 |
Since it has generally been accepted that the VOC in organic photovoltaics (OPVs) is proportional to the energy difference between the HOMO of donor and the LUMO of acceptor, it is indispensable for achieving high performance OPVs to tune LUMO and HOMO energy levels of donor and/or acceptor materials. Herein we report the synthesis and characterization of new organic molecules based on DPP as a donor material in OPVs. In order to precisely tune the energy level of the donor compound, we have introduced aromatic spacers with different electron-withdrawing (or donating) ability. The LUMO and HOMO energy levels of the new donor material are -3.5 eV and -5.2 eV, respectively, as estimated from the cyclic voltammetry. The frontier orbitals of the material are well aligned with those of fullerene acceptor, allowing the VOC of 0.7 ~ 0.8 V. The energy levels of DPP-based organic molecules are systematically analyzed in terms of molecular structure and correlated with VOC and the PCE of OPVs. |
