Improving the Efficiency of Organic Light-emitting Diodes Using Indium Tin Oxide Treated by H_2SO_4

We fabricated organic light-emitting diodes(OLEDs) with indium tin oxide anode treated by the H2SO4 solution.The efficiency of the OLEDs depended on the different concentration and ultrasonic time by the H2SO4 solution.When the concentration was 98% and the ultrasonic time was 10 min,the OLED exhibited the best efficiency and higher luminance than those of traditional devices.In particular,its efficiency can be increased by four times.Scanning electron microscopy measurements showed that those treated ITO anodes were much smoother which indicated that the adhesion between ITO and hole-transport layer was increased.Therefore,the efficiency of OLEDs was improved by the treatment of ITO anodes.