Influence of hole transporting material on device performance in organic light-emitting diode

We have studied the influence of hole transporting material on the electrol uminescence characteristics in two-layer devices based on tris(8-quinolinol ato) aluminum. Five hole transporting materials including two novel materia ls were used. No difference in turn-on voltages for light emission has been seen in the devices fabricated on indium-tin-oxide treated by argon/oxygen plasma, and a high luminance of 10000 cd/m(2) was achieved at an operating voltage around 10 V. However, the photometric efficiency depended on the h ole transporting material. High photometric efficiency of 6.1 cd/A and high luminous efficiency of 3.6 Im/W at a luminance of 300 cd/m(2) were obtaine d in one of the devices. (C) 2000 Elsevier Science S.A. All rights reserved .