Optimized indium tin oxide contact for organic light emitting diode applications

This work aimed to develop indium tin oxide (ITO) coatings with optimum opt oelectronic properties required for applications in organic light emitting diode (OLED) devices on flexible thin glass substrates. This involved intro ducing hydrogen in gas mixture during ITO film preparation using radio freq uency magnetron sputtering method. Uniform ITO films with resistivity of 2. 7 x 10(-4) Omega cm and transparency of 85% over the visible wavelength reg ion was achieved. The presence of hydrogen gas in the sputtering processes was shown to increase the number of charge carriers in the ITO films. The f easibility of using the ITO films with high carrier concentration was exami ned and tested in OLED devices composing a fluorene based polymeric hole tr ansporting layer (HTL) and green-emitting polymer, benzothiadiadzole-fluore ne. The devices made with different ITO substrates had an identical configu ration of ITO/HTL/emitter polymer/Ca (6 nm)/Ag (200 nm). The device showed that a maximum luminance of 4.36 x 10(4) cd/m(2) and an efficiency of 4.14 cd/A were achieved when an optimal ITO layer was used. These results an com parable with that of devices made with the best commercially available ITO products operated at the same conditions. (C) 2000 Elsevier Science S.A. Al l rights reserved.