Synthesis and characterization of novel organic materials for optoelectronic devices

TitleSynthesis and characterization of novel organic materials for optoelectronic devices
Publication Typeวิทยานิพนธ์/Thesis
Year of Publication2012
AuthorsTanika Khanasa
DegreePh.D (Major in Chemistry)
InstitutionFaculty of Science, Ubon Rachathani University
CityUbon Ratchathani
Call NumberQD T164
Keywordsacceptor, donor, dye solar cells, Dye-sensitized solar cells, Optoelectronics, Organic compounds--Synthesis, organic light-emitting diodes

This thesis deals with synthesis and characterization of four series organic materials including 2D-D-?-A TPA dyes, D-D-?-A DPA dyes, pyranemalononitrile dyes and A-D-A dyes, as well as D-A-D emitting materials. The compounds exhibit optical and electrochemical characteristic that relate to the conjugation length in molecules such as red shift in absorption and emission or lower in oxidation potentials as the number of thiophene increases. A large side of donor moiety prevents dyes aggregation and also reduces dyes among adsorbed on TiO2 resulting in lower in DSSCs efficiency. Pyranemalononitrile dyes exhibit good photophysical and electrochemical properties with the expanded absorption spectra by introducing the electron withdrawing moiety, pyranemalononitrile, into ?-conjugated bridge. Single donor double accepter dyes show good optical and electrochemical properties as well due to the increasing anchoring group, increasing the possibility of electron injection from dyes to TiO2 electrode. Among 12 dyes in this work, DPA3 with carbazole encapped-diphenylamine double electron donor, tertthiophene ?-conjugated bridge, and cyanoacrylic acid accepter exhibit the highest power conversion efficiency of 5.12%, whereas CFPA with carbazole-fluorene donor phenylene-(pyran-4-yilidine) malononitrile-bisthiophene spacer and acrylic acid accepter exhibits lowest power conversion efficiency of 0.82%.
For OLEDs materials, D-A-D type organic emitting materials exhibits the absorption, emission, and electrochemical characteristic that can be tuned by the conjugation system and electronic nature of the central core. DTBTD with benzothiadiazole core extended with two thiophene moiety shows fluorescence in red region due to the longest conjugation length and strongest electron affinity core. On the other hand DND without electron affinity core exhibits the emission in blue region due to the shortest conjugation length.

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