π-Conjugated Materials Containing Triazine Rings: Synthesis And Optoelectronic Properties

Over twenty years'development, organic light-emitting diodes(OLED) show a great potential for application in flat panel displays and solid state lighting. Small flat panel displays, such as digital display, have already been commercial in market. However, stability of organic membrane and balance of carrier mobility in OLED are two key problems restricting the further development of OLED.According to references, compounds comprised of dendrimer structure exhibit high stability. On the other hand, introduction of electron withdrawing groups, such as 1,3,5-Triazine, changes the energy level structure of the compound, reducing the HOMO energy and LUMO energy levels, which is benefit for electron transprot and hole blocking. Based on this, we designed and synthesized a series of dendrimers containing 1,3,5-triazine.These compounds possess good thermal stability. M1 and M2 show high thermal decomposition temperature of 396℃and 410℃, respectively. We found that these compounds have low HOMO and moderate LUMO energy level through optical and electrochemical characterization. And they are very suitable for OLED devices as the hole blocking materials.Using Ml as hole-blocking/electron-transport material and MADN as light-emitting material processed by evaporation, organic light-emitting diodes(OLED) were prepared. Result showed that the maximum luminance of the device was 2476 cd/m2, and the maximum efficiency was 0.88 cd/A. In EL spectra, the maximum emission peak was at 425 nm, which indicated these were typical blue devices. CIE coordinates of (0.15,0.09) was very close to (0.14,0.08), the international standards for blue emitting, established by International Commission on Illumination. The pure light emitting is attributed to effective blocking of hole into anode.In summary, a series ofπ-conjugated optical materials containing 1,3,5- triazine was synthesized and their optical and electronic properties were characterized. The relationship between electro-optical properties and the structure of these triazine-containing materials is discussed in detail, which would provides foundation and experience for further study of novel electro-optical materials.