Synthesis And Electrochromic Properties Of Star-shaped Oligothiophene Derivatives Based On Triphenylamine

Because of the excellent optoelectronic properties and charge transport capabilities, Oligothiophene and its derivatives have become the focus area of organic photoelectric materials. Up to now, the linear structure of p-doping electrochromic materials has been intensively studied, but star-shaped oligomers is rarely reported. Moreover, D-A structure has the advantage of adjusting band gap, which attract more concentration in optoelectronics. In order to develop new photovoltaic materials, we designed and synthesized a series of star-shaped oligothiophene derivatives based on triphenylamine combined with D-A structure, explored their use in electrochromic applications at the same time.In this paper, a series of star-shaped D-A oligothiophene derivatives with nitrogen as the “core” were synthesized. These star-shaped oligothiophene derivatives are: tris(4-(2’-thienyl)) phenylamine(3TPA), tris(4-(5’- aldehyde-2’-thienyl) benzyl) amine(3TPA-3CHO), tris(4-(2’-5’-18-amine-thienyl) phenyl) amine(3TPA-3NC18). The compounds were characterized by HRMS, NMR and IR.Their basic optical and electrical properties were measured by UV- visible spectroscopy, electrochemical work station and fluorescence spectroscopy, the band gap and fluorescence quantum efficiency were calculated at the same time, TGA analysis showed that these compounds have good thermal stability.The liquid and semi-solid state electrochromic devices were fabricated, which use the three compounds as active layer. Meanwhile, spectroelectrochemical, optical contrast and response time of the liquid state electrochromic devices were studied. The results showed that all the compounds exhibited good electrochromic performance and thermal stability, 3TPA showed reversible color change between blue and orange; 3TPA-3CHO can change color between pink and orange reversibly, 3TPA-3NC18 can change color between pale yellow and red reversibly. Response time of the three compounds were all less than 2s.The introduction of D-A structure make the materials have better properties.