Synthesis and investigation of photovoltaic properties for polymer semiconductors based on porphyrin compounds as light-harvesting units

We reported on two polymer semiconducting copolymers based on porphyrin compounds, poly[9,9-dioctylfluorene-co-5,15-bis(hexoxybenzyl)-10,20-bis(benzo-4-yl)porphyrin] (PFPor) and poly[9-(heptadecan-9-yl)carbazole-co-5,15-bis(hexoxybenzyl)-10,20-bis(benzo-4-yl)porphyrin] (PCPor), for use as organic photovoltaic materials. The thermal, optical, electrochemical, and photovoltaic properties of the two polymers were investigated. In addition, PC61BM and PC71BM were introduced as acceptor materials to confirm the acceptor effect in bulk heterojunction photovoltaic devices. Moreover, in order to establish acceptor effects, morphologies of polymer/PCBM blend films were analyzed through atomic force microscopy (AFM). PFPor and PCPor exhibited the best device performance with power conversion efficiencies (PCE) of 0.62% and 0.76%, respectively, upon the introduction of PC71BM as the acceptor in the device where 86 wt.% of the PC71BM was contained in the active layer (pol:PC71BM = 1:6, w/w).

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► A DA-type photovoltaic materials (PFPor and PCPor) with a porphyrin derivative as electron-withdrawing units.
► Both of the polymers exhibited low HOMO energy level of −5.31 eV.
► Photovoltaic cells with various active layer forming conditions were fabricated.
► The best photovoltaic performances were appeared in the devices where 86 wt.% of the PC71BM was contained in the active layer.
► PFPor and PCPor exhibited the power conversion efficiencies (PCE) of 0.62% and 0.76%, respectively.