The effect of the different donor units on fluorescent conjugated polymers containing 2,1,3-benzooxadiazole as the acceptor unit

•Low band gap polymers.•Multichromic polymers.•Donor effect on the optoelectronic properties.

A series of monomers were synthesized via Stille coupling to obtain low-band gap conjugated polymers namely poly(5,6-bis(octyloxy)-4,7-di(thieno[3,2-b]thiophen-2-yl)benzo[c][1,2,5]oxadiazole (PTTBO)), poly(5,6-bis(octyloxy)-4,7-di(selenophen-2-yl)benzo[c][1,2,5]oxadiazole (PSBO)) and poly(5,6-bis(octyloxy)-4,7-di(furan-2-yl)benzo[c][1,2,5]oxadiazole (PFBO)) which comprise electron-rich thieno[3,2-b]thiophene (TT), selenophene and furan, as the donor units in conjugation with electron-deficient 2,1,3-benzooxadiazole (BO) moiety as the acceptor unit. All three polymers were synthesized electrochemically and well characterized. These polymers exhibited broad spectral absorptions, low-lying highest occupied molecular orbital (−5.71, −5.88, −5.76 eV), and as well as low band gap ranging from 1.45 eV to 1.56 eV. Introducing different donor moieties on the polymer backbone provides to alter the optoelectronic properties.

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