Design, Synthesis And Optoelectronic Properties Of Indenochromene-, Thienocarbazole- And Quinoid-Based Dyes

In the past decades, much attention has been payed to organic optoelectronic materials and devices due to their wide application prospect in the fields of flexible display, flat panel lighting, high-density information transmission and storage, new energy and photochemical utilization, and so on. Organic semiconductor materials play an important role in organic semiconductor devices (for example, dye-sensitized solar cells, organic field-effect transistors). Their optophysical, electrochemical properties determine the device performance vastly. Design and synthesis of novel organic semiconductor materials with the advantages of low cost, high efficiency, high stability and environmental friendliness is an urgent task for promoting the development of organic optoelectronic devices. This will also lay the foundation for further study of structure-property relationship.TfOH-promoted cascade cyclization reaction of anisole-substituted aryldiynes was developed for the construction of indeno[1,2-c]chromenes. No other byproducts were found except for decomposition of starting material, indicating the good selectivity. Other advantages of this method included mild reaction condition, experimental simplicity. This reaction was very compatible with several functional groups, such as methyl, methoxy, halogen atoms (F and Br), cyano, nitro, phenyl, phenanthrenyl, cyclohexenyl, and naphthalenyl group with the yields of 40%-99%.In order to realize the application value of indeno[1,2-c]chromenes in the field of optoelectronic materials, D-?-A type organic dyes, JH132, JH344 and JH375, with indeno[1,2-c]chromene derivatives as electron donor moieties were designed and synthesized. DSCs based on these dyes achieved high photon-to-current conversion efficiencies of 5.07% ?6.71%. The results indicate that indeno[1,2-c]chromene derivatives are good electron donors. To improve the PCE of DSCs based on these dyes, amino groups were introduced to indeno[1,2-c]chromene structure. As a result, the broadened UV-vis absorptions increased the Jsc largely.D-?-A type organic dyes with thieno[3,2-a]carbazole derivatives as electron donor moieties were designed and synthesized. The PCEs of DSCs based on these dyes are in the range of 5.96%?8.04%. To improve the performance of DSCs based on these dyes, suppression of the charge recombination by introduction of steric groups is an efficient way. Compared with thieno[2,3-a]carbazole dyes, thieno[3,2-a]carbazole dyes exhibited better performance with more efficient intramolecular charge transfer.Fused symmetric tetracyano quinoid dyes JH04-JH10 with three to seven rings as backbone were designed and synthesized. Optical measurement showed very strong optical absorption at visible to near-infrared region, and the maximum absorption wavelength largely red-shifted with the increasement of ?-conjugation length. The electrochemical properties of these dyes showed LUMO energy levels of lower than -4 eV, indicating their air-stability. Organic field-effect transistors based on JH06 exhibited ambipolar charge transfer (?h= 5.3×10-3 cm2·V-1V1, ?e=7.7×10-3 cm2V-1s1). These unique properties make them good candidates for high-performance semiconductor materials. Finally, unsymmetric quinoid molecule, JH11, was synthesized. This molecule also displayed good air-stablity with LUMO energy level of -3.76 eV and bandgap of 1.77 eV.