Steric Hindrance Type Organic Semiconductor Material Synthesis And Electroluminescent Characteristics

Organic light emitting display and lighting device has its own outstanding advantages, including low power, high performance, and small size. The emphasis in the light elemitting device is life, and it depends largely on the spectral stability. Hindrance materials have morphological stability and thermal stability, and then decide on the material has good spectral stability. In this paper, we design molecular based on the concept of sterically hindered, and synthesis new electroluminescent phosphor host material and blue polyfluorene materials.Spiro[fluorine-9,9-xanthene](SFX) as the core, we successful introduce diphenylphosphate functional groups in position 2, position 2,7, position 2'and position 2',7'. The triplet energy level is 2.78eV, 2.70eV, 2.86eV and 3.83eV, respectively. They are suitable for blue PhOLED and green PhOLED as a host. Compared with SFX, the LUMO of them is lower 0.79⁰.85eV. The TGA test of them show high thermal stability, and the decompose temperature (T_d, 5%) of the double replaced compounds is 90°C higher than that of single replaced compounds. It achieves the maximum external quantum efficiency of 10.9% in blue phosphorescent devices, and the maximum external quantum efficiency of green light devices to 19.8% in green phosphorescent devices.Blue light polyfluorene as matrix, we introduce hindered amine functional groups in position 9 of fluorene. We have successfully synthesis five polymers by homopolymerisation or copolymerization for different ratio, including P1, P2, P3, P4 and P5. GPC test show number-average molecular weight is 45471, 70816, 77522, 22867 and 71290, respectively. The TGA tests of them show high thermal stability, and the T_d reach 400°C. Compared the green index (I_{Green, 527nm}/I_{Blue, 450nm}) in thermal annealing experiment, homopolymer P4 shows slow climbing in green index and the best performance.