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 π–π 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.