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New branched benzothiadiazole-cored conjugated oligomers with terminal carbazoles 1 and 2 have been synthesized. It was found that no obvious shifts of the maximal absorption bands for 1 and 2 were detected in the films compared with those in solutions, indicating weak π-π stacking occurred in the solid states on account of site isolation effect of the branched architectures. Hence, the synthesized oligomers could emit strong red light in the films. Notably, the emission of the films based on 1 and 2 could be quenched obviously upon exposed to gaseous TNT and DNT. The fluorescence quenching efficiency of the oligomer 2 -based film reached 91% when exposed to the saturated vapor of DNT for 3 min at 55 °C. The linear Stern–Volmer plot and the decrease of the fluorescence lifetime of 2 induced by DNT suggested the fluorescence sensing mechanism was due to the photo-induced electron transfer. [ABSTRACT FROM AUTHOR]

Abstract: Three new donor-π-acceptor (D-π-A) metal-free organic dyes, in which dendritic triphenylamine acts as donor, and furan, thiophene and benzene as π-linkers, were synthesized, characterized and used for the application of dye sensitized solar cell (DSSC). Among the fabricated DSSCs, the device based on the furan as π-linker exhibited a short circuit current density of 14.56 mA cm−2, an open circuit photo voltage of 0.71 V and a fill factor of 0.59, implying a power conversion efficiency (η) of 6.10%. The devices sensitized by dyes with thiophene and benzene as π-linker possessed relative lower η, 5.92% and 4.97%, respectively. [Copyright &y& Elsevier]