Abstract
In the thesis, we have synthesized the six phenanthrene derivatives, which show high energy gap and high thermal stability for blue fluorescent devices. The core phenanthrene structure incorporates two tert-butylphenyl groups at C-9 and C-10 positions to prevent extensive intermolecular □,□-interaction of the compounds in the solid state. In addition, the introduction of end-capping substitutes provides effective tuning of the emission wavelength, quantum yield and thermal property of the materials. On the other hand, TPyP showed a very high Tg of 211 °C with good thermal stability and surface morphology. We fabricated device 2G by utilizing TPyP as a host and BCzVBi as a dopant. Device 2G employing TPyP as a host material achieved excellent EQE of 6.4 %, and current efficiency of 7.7 cd/A. At luminance between 10 to 10000 cd m-2, the EQE of TPhP- and TNaP-based devices 2E and 2F showed relatively high efficiency roll-off. But surprisingly, the efficiency of the TPyP-based device 2G increases gradually as the luminance increases from 10 to 10000 cd m-2. The performance and operational lifetime of device 2G can be further improved by inserting a thin layer of MoO3 between ITO and NPB. Device 2H thus fabricated shows an EQE and current efficiency as high as 7.7% and 9.8 cd/A, respectively. We try to design and synthesize the highly efficient and thermal stable pyrene and phenanthrene derivatives for deep blue fluorescent devices. The π-π stacking of the polyaromatic compound will cause the red-shifted and self-quenching effect seriously. To improve this drawback, the core pyrene and phenanthrene structure incorporates different number of tert-butyl groups and positions to prevent extensive intermolecular □,□-interaction of the compounds in the solid state. The blue fluorescent materials, PPy, PTP, TPy and TTP, were synthesized to estimate the characteristic and performance of devices. In the host/dopant system EL devices, we fabricated device 3F by utilizing PTP as a host and BCzVBi as a dopant. Device 3F showed maximum external quantum efficiency of 8.2%, current efficiency of 7.5 cd/A, power efficiency 4.52 lm/W, and excellent CIE coordinates of (0.14, 0.10), respectively. This performance is higher than the previously reports.