Synthesis And Characterization Of Light-emitting Polymers

Organic light-emitting diodes(OLED)have attracted much attention because of their potential applications for multicolor emission with many advantages such as active emission,fast response,wide view-angle and simple fabrication process.As the present time,low power-conversion efficiency,short useful life and bad long-term stability are the critical problems to block the utility and marketization of OLED.However,exploiting organic light-emitting materials with high efficiency and stable physic characteristics,choosing appropriate electrode materials,searching for new film fabrication process,and optimizing device configuration,improving the efficiency and useful life of device,and questing for the best scheme to realize full color are still the primary aims of study work.Consequently,this work is dedicated to the Synthesis and purification of materials as follows.Poly(spirobifluorene-3,6-diyl-alt-9,9-diphenylfluorene-2,7-diyl)(PF) and its copolymer with triphenylamine derivative (PF-TPA) were synthesized via Suzuki coupling reaction. The optical and the electroluminescent properties of the materials were investigated and we found that the polymer light-emitting devices (PLEDs) based on these obtained polymers show a low turn-on voltages of 5 V, as compared to that of the devices based on the corresponding poly(3,6-fluorene) material (about 15 V). With a device configuration like ITO/PEDOT:PSS/PF-TPA/Ba/Al, a maximal luminous efficiency of 1.43 cd A-1 (corresponding to an external quantum efficiency of 4.3 %) was obtained, with the Commisssion Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.10), which is very close to the National Television System Committee (NTSC) standard (0.14, 0.08). The deep blue emission together with the high color purity and the high EQE, make these polymers promising candidates for blue emitting PLEDs.New phenyl substituted PPV : Poly ( 2- ( 3-(3,7-dimethyloctyloxy)phenyl ) - 1,4-dimethylene benzene)and Poly(2-(4-(3,7-dimethyloctyloxy)phenyl)- 1,4-dimethylene benzene)(EHP-PPV)were synthesized via Gilch reaction.The polymers were detected by NMR(1H and 13C). The optical and the electroluminescent properties of the materials were investigated and we found an external quantum efficiency of 8 % and a maximal luminous efficiency of 19~20 cd A-1.