PS-TPD空穴传输层的高亮度绿光有机电致发光器件的研究

Study on High-Brightness Green Organic Light-Emitting Devices Using PS-TPD as Hole Transporting Layer

研究了不同质量比的聚苯乙烯（PS）-三苯基二胺（TPD）复合空穴传输层对有机电致发光器件（OLED）性能的影响。采用此掺杂体系作器件的空穴传输层，利用旋涂工艺制备了结构为indium-tin-oxide（ITO）／polystyrene（PS）：N，N′-bis（3-methylphenyl）-N，N′-diphenylbenzidine（TPD）／tris-（8-hydroxyquinoline）-aluminium（Alq3）／Mg：Ag的双层有机电致发光器件。为便于比较，另直接蒸镀TPD薄膜做空穴传输层制备了相似结构的器件。利用飞行时间法对不同PS-TPD质量比例的薄膜的空穴迁移率进行了表征，并对器件的电致发光特性进行了测试。测试结果表明，掺杂薄膜的空穴迁移率比纯TPD膜的低1～2个数量级。当质量比为m（PS）：m（TPD）=10：90时，器件具有最高光亮度14280cd／m^2和最高流明效率1．2 lm／W。说明适当质量比PS的引入相对降低了薄膜的空穴迁移率，调节了TPD的空穴传输能力，更有效地平衡了复合区内正负载流子的数目，从而提高了器件的发光亮度和效率。

The effect of the composite hole transporting layer with different polystyrene （PS）-triphenyl diamine （TPD） mass ratios on the performance of organic light-emitting devices （OLEDs） was investigated. By using this blending system as hole transporting layer, a double-layer organic light-emitting device was fabricated with the structure of indium-tin-oxide （ITO）/polystyrene （PS）, N, N′-bis （ 3-methylphenyl）-N, N′-diphenylbenzidine （TPD） / tris-（8-hydroxyquinoline）-aluminum （Alq3）/Mg： Ag by the spin-coating technique. For comparison, a similar doublelayer device was fabricated using pure TPD as hole transporting layer by thermal vacuum deposition method. The hole drift mobility of PS-TPD thin films with different mass ratios was characterized by time-of-flight method, and electroluminescent characteristics of these devices were measured. Results demonstrated that the hole mobility of blending thin films is 1 - 2 orders of magnitude lower than that of pure TPD film. When the mass ratio is m （PS） ： m（TPD）=10： 90, the device has a maximum luminance of 14280 cd/m^2 and a maximum lumen efficiency of 1.2 lm/W. It was concluded that the incorporation of PS with proper concentration will lower the hole mobility of the functional layer, adjust the hole transporting ability of TPD, more effectively balance the number of positive and negative charge carriers in the recombination zone, and thus enhance the luminance and efficiency of the device.