ABSTRACT
A new low-molecular-weight porphyrin-based polymer, PPPyDPP, with pyridine-capped diketopyrrolopyrrole (DPP) has been synthesized, and its optical and electrochemical properties were investigated. The polymer is prepared with a low content of homocoupling units and gives a widely spread absorption from 400 to 900 nm with a narrow optical band gap of 1.46 eV. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are respectively located at -5.27 and -3.78 eV, respectively. PPPyDPP was used as the electron donor, whereas [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) and bis(rhodanine)indolo-[3,2-b]-carbazole (ICzRd2), a nonfullerene small molecule, were used as acceptors for the fabrication of solution-processed bulk heterojunction polymer solar cells. Overall power conversion efficiencies (PCEs) of 7.31 and 9.16% (record high for porphyrin-containing polymers) were obtained for PC71BM and ICzRd2, respectively. A high Voc of 1.01 V and a low Eloss of 0.45 eV may explain this new record.
ABSTRACT
A porphyrin-containing polymer exhibiting various degrees of Glaser-Hay coupling is reported. Sonogashira polycondensation of zinc(II) (5,15-bis[3,4,5-tri(2-butyloctyl)phenyl]-10,20-bis(ethynyl)porphyrinate) with N, N'-bis( p-iodobenzene)-2,3,5,6-tetrafluorobenzoquinone-1,4-diimine (fQI) is found to be prone to homocoupling, a problem underestimated in the literature. 1H NMR and photophysical analysis are used to assess the ratio of Glaser versus Sonogashira couplings. Optimized conditions to perform Glaser-free Sonogashira polycondensations are provided, and the optimization increases Mn from 9700 to 18â¯900. Applied to a conjugated polymer, it shows both decreasing homocoupling and 180% enhancement in Mn.
ABSTRACT
A porphyrin-diketopyrrolopyrrole-containing polymer (poly(porphyrin-diketopyrrolopyrrole) (PPDPP)) shows impressive molar absorption coefficients from λ=300 to 1000â nm. The photophysical and structural properties of PPDPP have been studied. With PPDPP as the electron donor and [6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) as the electron acceptor, the bulk heterojunction polymer solar cell showed overall power conversion efficiencies of 4.18 and 6.44 % for as-cast and two-step annealing processed PPDPP:PC71 BM (1:2) active layers, respectively. These results are quite impressive for porphyrin-containing polymers, especially when directly included in the π-conjugated backbone, and offer interesting perspectives for the design of new materials based on this chromophore.
