ITO表面改性对有机电致发光器件性能的影响

Influence of Surface Modification of IndiumTin Oxide on Performance of Organic Light Emitting Diodes

采用乙醇、氧等离子、NaOH、浓硫酸分别对氧化铟锡薄膜进行了处理;利用原子力显微镜、X-射线光电子能谱、接触角测试仪对处理后薄膜的表面形貌、化学组分及表面能进行了研究。实验结果表明经浓硫酸和NaOH处理后的氧化铟锡薄膜表面具有较低的粗糙度、较小的表面颗粒半径、较低的碳污染以及较高的表面能;另外,以不同材料处理的氧化铟锡基片为阳极采用真空热蒸发法制备了双层结构发光器件ITO/NPB/AlQ/Mg:Ag/Ag,并对器件的电流-电压(J-V)、亮度-电压(B-V)特性以及效率(η)进行了测试和分析,结果表明乙醇处理基片做制备器件性能最差,而经浓硫酸、NaOH处理后的氧化铟锡基片所制备的双层器件的光电性能优于氧等离子处理,其启亮电压更低,发光亮度及效率更高。

Surface of Indium Tin Oxide （ITO） films on glass substrates were treated by ethanol, oxygen plasma, NaOH, and sulfuric acid, respectively and then analyzed by Atomic Force Microscope （AFM）, X-ray Photoelectron Spectroscopy （XPS） and goniometer. Results show that ITO films treated by sulfuric acid and NaOH have low roughness, small grain radius, low contamination of carbon, and high surface energy. Double layer Organic Light-Emitting Diodes （OLEDs）： ITO/NPB （15 nm）/AIQ （40 nm）/Mg：Ag （10：1, 100 nm）/Ag （50 nm） were fabricated on substrates treated above. Current-voltage （J-V）, brightness-voltage （B-V）, and efficiency （η） characteristics of these devices were measured and discussed in details. Experimental results show that devices based on NaOH-treated and sulfuric-acid-treated substrates have better performance comparing with oxygen-plasma-treated substrate, namely lower turn-on voltage, higher electroluminescent brightness and higher efficiency.