Implications of Multichromophoric Arrays in Organic Photovoltaics

Abstract

A covalently linked multichromophoric array (BDP-Por) was used as the donor layer in planar heterojunction organic photovoltaic (OPV) cells with the structure ITO/BDP-Por/C60/BCP/Al (BCP = bathocuproine). BDP-Por is a platinum tetrabenzoporphyrin (PtTPBP) core bonded through the phenyl groups to the meso position of four 4,4-difluoro-3,5-dimethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY) moieties. The OPV outperforms analogous OPVs that use only the PtTPBP as the donor, predominantly by producing a higher short-circuit current (JSC of 2.5 mA/cm2 vs 4.5 mA/cm2), because of the enhanced absorptivity of the multichromophoric array. The open-circuit voltages (VOC) for PtTPBP- and BDP-Por-based OPVs are both 0.65 V. The system was further investigated by preparing and testing OPVs made from an analogous system with porphyrin and BODIPY components blended into a single homogeneous donor layer that absorbs like the array. It is then found that the mixed system generates the same photocurrent as the array with a sim...