Level III, retrospective comparative study.

In this study, we present the polarization property of an organic light-emitting diode characterized by a low-energy and high-linearity ion-beam-treated MoS2 hole-transport layer deposited by using radio-frequency sputtering in order to obtain highly-polarized light. Poly (9,9-dioctylfluorene-altbenzothiadiazole), which exhibits a liquid crystal phase at a temperature higher than 180 • C, was used as the light-emitting material. The polarization characteristics of the organic light-emitting device fabricated under various ion-beam irradiation conditions were examined through photoluminescence experiments. The results showed that an optimal polarization ratio of 11:1 was obtained for a ion-beam-irradiated angle of 30 degrees, an irradiation time of 30 seconds, a current density of 100 µA/cm 2 , and an ion-beam energy of 300 eV. When the optimized organic light-emitting diode was used as a backlight for a twisted nematic liquid-crystal display, its transmittance was improved by about 25% or more.