Design And Synthesis Of Blue Fluorescent Emitting Materials And Study Of White Organic Emitting Devices

Recently, Organic Light Emitting Diodes (OLEDs) have drawn much attentionattention for their applications in flat-panel displays and solid-state lightings due to theiroutstanding performance. Compared with red and green organic electroluminescentdevices, the blue emitters whose performance are typically far below those of red andgreen emitters. Therefore, it is necessary to design and synthesize new blue emitters forhandle the issue. Blue emitters always possess high band gap energy, a good blueemitting material have the properties of:1, High carrier charge transport property canpromote the radiation recombination of excitons generated by holes/electrons.2, Goodmorphological and thermal stability can help to form amorphous film so that thestability and lifetime of the device can be improved. Therefore, It is a hard work todesign and synthesize a high performance blue emitter.1. synthesised of four fluorescent materials are BNPPS, DMNPS, DTPPS,DSB-DBA. The maximum absorption peaks are located at350nm and260nm forDTPPS and BNPPS, and the emission peak wavelength are360nm and380nm forBNPPS and DTPPS. The triplet energy were estimated to be2.5and2.0eV for BNPPSand DTPPS, The HOMO energy levels of materials BNPPS and DTPPS were estimatedto be-5.6and-5.9eV. The optical energy band gaps (Eg) for these compounds were3.2and3.3eV, The LUMO energy levels of BNPPS and DTPPS were calculated to be-2.4and-2.6eV.2. Depth study on the EL performance of BNPPS and DTPPS based blue devicesdemonstrate good results. A blue phosphorescent device based on DTPPS obtained amaximum power efficiency of5.0lm/W, the maximum current efficiency of5.6cd/A,with CIE coordinates of (0.15,0.25), the turn on voltage is3.4V, the emission peakwavelength is476nm, it shows good performance. A blue phosphorescent device basedon BNPPS obtained a maximum power efficiency of0.6lm/W, the maximum currentefficiency of0.9cd/A, the device turn on voltage is4.1V, the emission peak wavelengthis440nm, along with coordinates of (0.15,0.07), it shows the good performance ofcolor uniformity and the deep-blue property. 3. Triplet energy of BNPPS is higher than those of other commonly used bluefluorescent materials and phosphorescent orange/red emitters. High performance orangeand white OLEDs also were obtained by using BNPPS as a host. An orangephosphorescent device based on BNPPS exhibits a maximum power efficiency of20.5lm/W and the maximum current efficiency of22.8cd/A, the device turn on voltage is3.8V, the emission peak wavelength is584nm, with the CIE coordinates of (0.56,0.43).It indicate that BNPPS could be used as host material. The performance is better thanthe CBP based devices with the same structure. A white color OLED based on BNPPSwas fabricated, the device shows a maximum power efficiency of17.8lm/W (22.7cd/A)and CIE coordinates of (0.37,0.37). The CIE coordinates of (0.45,0.41) at1000cd/m2.In this thesis, design and synthesis of four blue fluorescent material, and test thematerial properties, a detailed study based on the aboved mentioned materials andobtained a good result. The results could provide more theoretical foundation fordesigning a blue emitter and provide more chioce for blue organic emitting materials,therefore improve the development of solid lighting and flat panel display.