Synthesis and characterization of novel organic materials for optoelectronic devices

This thesis dealt with the synthesis and characterization of four series of organic materials, D--A carbazole dendrons-based donor dyes, D-D--A carbazole-carbazole-based donor dyes for dye-sensitized solar cells (DSSC), D-A-D benzothiasdiazole-core-bases red emitting materials for organic light-emitting diodes (OLED), and triindole-cored based narrow band blue and green organic photodiodes for imaging. A series of novel D--A type organic dyes, namely, GnTA (n=1-4), containing carbazole dendrons up to the fourth generation as a donor, bithiophene as -linkage, and cyanoacrylic acid as an acceptor were synthesized and characterized for applications in DSSC. The photophysical, thermal, electrochemical, and photovoltaic properties of the new dyes as dye sensitizers were investigated, and the effects of the carbazole dendritic donors on these properties were evaluated. Results demonstrated that increasing the size or generation of the carbazole dendritic donor of the dye molecules enhanced their total light absorption abilities and reduces the amounts of dye uptake per unit TiO2 area because of their high molecular volumes. Among them, dye G1TA containing first generation Dendron as a donor (having the lowest molecular volume) exhibited the highest power conversion efficiency of 5.16% (Jsc=9.89 mA cm-2, Voc=0.72 V, ff=0.73) under simulated AM 1.5 irradiation (100 mW cm-2). The researcher synthesized and proved a series of organic sensitizers with the direct electron injection mechanism. High molar extinction coefficient dyes comprising double donors, a -spacer, and anchoring acceptor groups (D-D--A type) were synthesized and characterized experimentally for DSSC. Results showed that these materials are good candidates for DSSC and the performance is under investigation and will be reported in the future. Moreover, photodiode materials, triindole as the core molecule TN1-3, were designed and synthesized, and their optical, electrochemical, and thermal properties investigated in detail. All materials exhibited good thermal stability and intensive absorption in specific blue and green regions with a response of full width at half maximum less than 100 nm. The transport and photodiode properties will be investigated and reported in the future.