Bandgap copolymers

A low bandgap copolymer consists of poly(2,7-(9,9-dioctyl)fluorene-co-5,5 -(4,7-diselenophenyl)-2,... 

Steyrleuthner R, Schubert M, Howard I, Klaumunzer B, Schilling K, Chen ZH, Saalfrank P, Laquai E, Eacchetti A, Neher D (2012) Aggregation in a high-mobility n-type low-bandgap copolymer with implications on semicrystalline morphology. J Am Chem Soc 134 18303... 

Fink Y., Urbas A.M., Bawendi M.G., Joannopoulos J.D., and Thomas E.L. Block copolymers as photonic bandgap materials, J. Lightwave Tech., 17, 1963, 1999. 

Osuji C, Chao CY, Bita 1, Ober CK, Thomas EL. Temperature-dependent photonic bandgap in a self-assembled hydrogen bonded liquid-crystalline block copolymer. Adv Funct Mater... 

These copolymers are both p- and n-dopable, as follows from their electrochemistry, with bandgaps of 2.2 and 2.0 eV for 558 and 559, respectively. The efficiency of similar fluorene copolymers was much lower. The combination of thiophene and thiophene-S,S-dioxide units in a copolymers allows tuning of the emission color from green to pure red (02MI192 03SM(138)289). 

Copolymer between 3-octylthiophene and 3-decyloxythiophene has been described (06JA8980). They showed an absorption band at 538 nm in chloroform and at 621 nm in film, with a bandgap of 1.64 eV. 

Narrowing the bandgap of copolymers by alternation of electron-rich thiophene and electron-deficient benzo-l,2,3-thiadiazole units was used in the design of several LEPs whose optical and electronic properties could be tuned through such a modification. Cao and coworkers synthesized copolymers 599 and 600 (02MI2887 04MM6299), exploiting random copolymerization. 

FIGURE 14. Plot of the bandgaps (Iif) determined from absorption edge versus silole/thiophene ratios for a series of silole-thiophene copolymers. Reproduced by permission of Wiley-VCH from Reference 45... 

These two strategies are illustrated on Fig. 36. More generally, it is possible to conceive regular block copolymers in which both components would be CPs, so as to adjust the bandgap and/or the electron localization... 

Since PDAFs are wide bandgap materials, incorporation of other smaller bandgap chromophores as comonomers or substituents enables tuning of the emission colour due to efficient energy transfer from the fluorene to the other units. Random copolymers of fluorenes with other chromophores are readily prepared by the copolymerisation of the dihalochromophore with a dihalofluorene as exemplified in Scheme 9 for the synthesis of copolymers of dioctylfluorene with perylene dyes (1-5 mol%) [46,47]. 

Zhang F, Perzon E, Wang X, Mammo W, Andersson MR, Inganas O (2005) Polymer solar cells based on a low-bandgap fluorene copolymer and a fullerene derivative with photocurrent extended to 850 nm. Adv Funct Mater 15 745... 

Zhang F, Mammo W, Andersson LM, Admassie S, Andersson MR, InganHs O (2006) Low-bandgap alternating fluorene copolymer/methanofuUerene heterojunctions in efficient near-infrared polymer solar cells. Adv Mater 18 2169... 

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