Synthesis And Properties Of Organic Electroluminescent Materials Based On Anthracene Derivatives

Organic light-emitting diodes (OLEDs) have drawn great scientific and commercial attention in the past decades, due to their potential applications in full-color, flat-displays as well as solid-state lighting. The electroluminescent materials play a very important role in OLEDs, which largely affect the process of industrialization of OLEDs. Therefore, it is very important to study and explore the high-efficiency and stable materials. Anthracene derivatives have been intensively studied and applied in OLEDs, due to their rigid structure, high energy gap, high fluorescent quantum yield, amorphous thin film morphology, excellent thermal stability, balanced carrier mobility, as well as easier modification. Moreover, the anthracene derivatives are focused on the application because of their practical value and prospects in OLEDs.In this thesis, a series of functionalized anthracene derivatives by introducing different groups at the 9,10 or other positions of anthracene unit based on fantastic electro-optical properties of anthracene derivatives were synthesized and characterized, also were applied in OLEDs to study their electroluminescent properties. The main research contents and results were generalized as follows:In chapter 1, the basic concept, property parameter, device structure and recent progress of organic light-emitting diodes are reviewed. Especially, the development and application of anthracene derivatives were particularly introduced.In chapter 2, a series of bipolar anthracene derivatives containing hole-transporting triphenylamine and electron-transporting benzimidazole moieties were synthesized and characterized. These compounds possess high thermal properties and quantum yield in toluene solution, but their photoluminescence spectra are sensitive to the polarity of the solvent. The two-photon excited fluorescence characteristics of the bipolar anthracene derivatives in both toluene and THF solution have been measured. Three types of devices were fabricated to investigate their electron-transporting, hole-transporting as well as light-emitting properties. The electroluminescent spectra for the three derivatives B1, B3 and B4 show that they emit blue light, while the B2-based devices produced white light at a low current density because of the electromer formation. Moreover, a single layer OLED device for B4 exhibited a current efficiency of 3.33 cd/A with a pure blue color of CIE(x,y) of (0.16, 0.16) at 20 mA/cm2 and a maximum brightness of 8472 cd/m2 at 8.7 V.In chapter 3, two unsymmetrically amorphous 9,10-disubstituted anthracene derivatives have been synthesized and characterized. They emit the light in the blue region and possess glass transition temperature of 132.5℃and 133.8℃. The scanning electron microscope (SEM) was employed in studying the thin film morphological stability of the two unsymmetrical isomers. These two compounds were fabricated into typical trilayers devices with pure blue lighting performance. In addition, a series of highly efficient and stable sky blue devices doped with a sky blue dopant BUBD-1 have been fabricated by using these two isomers as the host.In chapter 4, a new series of anthracene derivatives containing a truxene moiety as the core have been synthesized and characterized. They emit in the blue region with excellent solution fluorescence quantum yields and possess high thermal decomposition temperature (Td>458℃). Typical electroluminescence performance was demonstrated by NPAT as the blue lighting material in the OLED with structure of ITO/CFx/NPAT/TPBI or Alq3/LiF/Al. Additionally, the effects of the different thickness of the different electron-transporting layers on the device performance were investigated.In chapter 5, we synthesized and characterized one electron-transporting material containing anthracene and benzimidazole moieties, and measured the HOMO energy level and LUMO energy level with 5.7 eV and 2.7 eV through cyclic voltammery (CV) analyses. The compound was applied in the green and blue devices as electron-transporting layer to achieve the better performance than those Alq3-based devices. The electron-only and electron-injection devices were also fabricated to study its electron-transporting and electron-injecting properties.In chapter 6, a new series of anthracene derivatives based on the common MADN by introducing the functional moiety including the triarylamine or benzimidazole at the 2 position of anthracene were synthesized and characterized. The introduced group can not only turn the emitting light and thermal stability, but also affect the emission and charge transporting properties of these materials.In chapter 7, two hole-transporting materials based on the hexaphenylbenzene were synthesized and characterized.The chapter 8 is conclusion...