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 Publication2009
AuthorsPalita Kochpradist
DegreeMaster of Science -- Major in Chemistry
InstitutionFaculty of Science, Ubon Rachathani University
CityUbon Rachathani
Call NumberQD P163
KeywordsOptoelectronics, Organic compounds -- synthesis

This thesis deals with synthesis and characterization of novel donor pi-conjugates aceptors (D-pi-A) organic materials for using as dye molecules in optoelectronic devices. This D-pi-A organic materials consists of a carbazole moiety as an electron donor, fluorine-phenyl-pyran moiety as a conjugated linker and different electron acceptor. Cyanoacrylic acid, acrylic acid acid or cyanocarylamide groups was applied as the electron-withdrawing parts and anchoring group for the application in dye solar cells (DSCs). The target molecules were characterized by 1H-NMR and 13C-NMR, and FT-IR techniques. The target molecules exhibited a adsorption band cover UV and visible region. The absorption maximums of the target molecules were more or less blue-shifted with an increase in the number of phenyl units. Fluorescence spectra of the target molecules excited at max of each molecule show emission peak at blue-green region. Most compounds show high thermal stability good electrochemical property, with dye having unsubstituted carbazole donor. Oxidative coupling of carbazole group at surface of working electrode being observed. DFT calculations have been performed on the dyes. The results show that electron transfer from the donor part of molecules to the anchoring moieties via the pi-conjugated bridge occurs during the HOMO-LUMO excitation. The electron-withdrawing groups are coplanar with respect to the phenyl units. A maximum  value of 1.55% is achieved under simulated AM 1.5 irradiation (80 mW/cm2) with a DSCs based on CFP11 dye (Voc=0.72 V, Jsc=2.65 mA/cm2, ff=0.65). Under the same conditions, the  value of a DSCs based on N3 dye is 2.62% (Voc=0.63 V, Jsc=6.77 mA/cm2, ff=0.49). By applying the electron-withdrawing parts of methylenemalononitrile, methylcyanicrylate and methyleneindene-1,3-dione as aceptor group provide the D-pi-A type luminescent organic materials for the application in organic light-emitting diodes (OLEDs). All compounds in this study are fluorescent with the color ranging from blue to green. All targets have good thermal and electrochemical stabilities and could be used as emissive layers in OLEDs. The performance of OLEDs using these materials as light-emitting layer is under investigation and will be reported in the future.

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