Synthesis and photocurrent response of porphyrin-containing conjugated polymers

Abstract

Porphyrin-containing conjugated polymers with fluorene or carbazole as spacer groups were prepared by Sonogashira cross-coupling reactions. The polymers were of high molecular weight and the flexible alkyl chains on fluorene or carbazole units made the conjugated polymers soluble in common organic solvents, such as THF and methylene chloride. The polymers could form high quality durable films from solution casting. Their optical and photocurrent responsive properties were investigated. It was found that the photocurrent response was directly proportional to the content of porphyrin. The incorporation of carbazole units into the polymer chains also gave positive contribution to the photocurrent generation in some extent.In recent years conjugated polymers have attracted considerable attention because of their potential applications in the fields of light emitting diodes, photovoltaic devices, and sensors [1][2][3][4][5][6][7] . In the fabrication of semiconductor photovoltaic devices, conjugated polymers have many advantages, such as low cost, suitable for solution process and large area application, over inorganic semiconductors. The efficiency of photovoltaic cells continues to rise with the development of new materials and the improvement of the device structures. The development of highly efficient new conjugated polymers for photovoltaic applications remains a challenge in this area.It is our long-term goal to synthesize porphyrin-containing macromolecular architectures and to exploit their optoelectronic properties. The incorporation of porphyrins into the main backbone of the conjugated polymers is of special interest, because porphyrins are well known as the natural photosynthetic reaction center in green plants. Much effort has been devoted to the design and synthesis of porphyrin-containing macromolecules, including dendrimers [8 -11] , linear oligomers [12][13][14][15][16][17] , and polymers [18][19][20][21][22][23][24][25][26][27][28][29][30][31] . In our previous papers, we have synthesized a set of fluorene-based porphyrin monomers, star-shaped oligomers, and hyperbranched polymers [32,33] . The alkyl chains on fluorene units could increase the solubility of the porphyrin rings without interrupting the conjugated connections. Here, we report the synthesis of a set of porphyrin-containing conjugated polymers, which are suitable for the fabrication of heterojunction solar cells. In order to increase the charge transport ability, we also copolymerize A 2 B 2 porphyrin monomers with carbazole monomers. In the initial photocurrent generation studies, we found that the contents of porphyrin and carbazole units in the polymer main chains played very important roles. Experimental MaterialsAll reagents were obtained from commercial suppliers and used without further purification unless otherwise indicated. Tetrahydrofuran (THF) was distilled from Na-benzophenone under nitrogen. Triethylamine (TEA), diisopropylamine and pyrrole were distilled over CaH 2 . N,N-dimethylformamide (DMF) was dried over molecular s...

The Implication of 1,3‐Dipolar Cycloaddition of Azomethine Ylides to the Synthesis of Main‐Chain Porphyrin Oligomers

“…Porphyrins have been incorporated in polymers as pendant groups, [ 21,23 ] as a framework of linear [ 18,19,[24][25][26][27] or branched [ 28 ] covalent polymers, as a core [29][30][31][32] or a backbone [ 24 ] of dendrimers, as a backbone of an extended network [ 33 ] and as a backbone in supramolecular polymeric ensembles. [ 21,24 ] In the present work, we report the fi rst example of a polymerization based on the 1,3-dipolar cycloaddition of azomethine ylides to bisdipolarophiles, that leads to a linear oligomer containing pyrrolidine fragments in the main chain ( poly-1 , Scheme 2 ), as well as illustrate its synthetic usefulness by synthesizing linear oligomers (Table 2 ), which corresponds well to the molecular mass…”

“…Porphyrins have been incorporated in polymers as pendant groups, as a framework of linear or branched covalent polymers, as a core or a backbone of dendrimers, as a backbone of an extended network and as a backbone in supramolecular polymeric ensembles …”

Incorporation of zinc(ii) porphyrins in polyaniline in its perigraniline form leading to polymers with the lowest band gap

“…Conjugated metalloporphyrin-containing polymers have been the subject of intense interest as they offer the possibility of low-band gap excited states and many studies on their solar cells have been reported. [1][2][3][4][5] Similarly, these materials are also found to be electroluminescent and light emitting diodes were studied. [6][7][8] Moreover, a series of conjugated Pt-polyynecontaining polymers and oligomers were recently prepared (Chart 1; top), 9 and the design of solution-processed bulk heterojunction polymer solar cells containing porphyrin exhibiting the best photocurrent efficiency (1.04%) were reported (Chart 1; bottom).…”