磷酸处理ITO基底对有机发光二极管性能的改善

Phosphoric Acid Treatment of ITO Substrate for Improvement of OLED Performance

用10%、15%、20%3种浓度(体积分数)的磷酸分别对ITO玻璃进行处理,四探针测试表明其面电阻基本不变,原子力显微镜观测到酸处理后的ITO表面形貌更加平坦,紫外-可见光光谱显示出磷酸处理几乎不影响可见光透过率;以之为基底制备了典型结构(ITO/TPD/Alq/Al)有机发光二极管(OLEDs),并对其光电性能进行了测试,结果表明在经过浓度为15%的磷酸处理过的ITO玻璃上制备的OLEDs表现出最好的光电性能,其发光最大亮度和发光效率分别是未经酸处理的ITO上器件的近2倍。

ITO-coated glass was immerged in phosphoric acid （H3 PO4 ） with three kinds of concentration of 10 %, 15 %, 20 %（volume fraction）,respectively. The observation with an atomic force microscopy （AFM） reveals that the surface roughness of the treated ITO film with the acid was remarkably improved. The record with a UV-visible light photometer indicates that the transparence of the ITO film keeps nearly unchanged after being treated with the phosphoric acid. The electrical and optical characteristics of OLEDs, which were fabricated on the treated ITO-coated glass with the classic structure of ITO/TPD/Alq/Al, were measured and compared with diodes prepared on the untreated sample. The results show that the diodes, which on the ITO treated with 15 % H3PO4, demonstrated the best photoelectric performance, in which the EL luminance and current efficiency has been promoted more nearly two times than that of the original devices, respectively.