All-Porphyrin Photovoltaics with Power Conversion Efficiency of 7.2%

In this Letter, two zinc porphyrin small molecules D1 and A1 with different functional groups have been employed as the donor and acceptor, respectively, for the construction of all-porphyrin photovoltaics (APPS). The strong electron-donating phenylamino moiety ensures the D1 small molecule with a high-lying highest occupied molecular orbital energy level aligns a cascade energy level with the A1 small molecule, accomplishing the driving force for exciton dissociation and prompting intermolecular pi-pi stacking to ameliorate the intermolecular charge transport. Meanwhile, good complementary absorptions between D1 donor and A1 acceptor greatly contribute to harvesting more solar flux. For the optimized devices, 1:0.5 D1:A1 device delivered a relatively high power conversion efficiency of 7.21% with an open-circuit voltage of 0.76 V, a short-circuit current density of 14.43 mA cm(-2), a fill factor of 65.7%, and a small energy loss of 0.61 eV.