Dimeric Porphyrin Small Molecule for Efficient Organic Solar Cells with High Photo-Electron Response in Near Infrared Region.

Small molecules with elongated backbones are promising for achieving higher photovoltaic performance. Herein, a dimeric porphyrin small molecule ZnP2-DPP consisting of two porphyrin units linked with an ethynylene as the core and two diketopyrrolopyrrole (DPP) units as the arms is designed and synthesized as an electron donor for solution-processed organic solar cells (OSCs). And a significantly enhanced power conversion efficiency of 8.45% with an impressive short-circuit current density (JSC) up to 19.65 mA cm-2 is achieved for the OSCs based on ZnP2-DPP under AM 1.5G irradiation (100 mW cm-2) compared to those based on the dimeric porphyrin linked with bis-ethynylenes reported previously. Furthermore, the devices show broad photo-electron response up to 1000 nm with high near infrared external quantum efficiency up to 66% at 780 nm. This is the first report that SM OSCs show such a large JSC about 20 mA cm-2 simultaneously with a considerably high and deep photo-electron response up to 1000 nm.