Effect of inverted-pyramid shape on light extraction of organic light-emitting diodes

Light extraction efficiency of organic light emitting diode (OLED) was enhanced by attaching a thin film with inverted-pyramid texture onto a glass substrate. Two groups of polyvinyl alcohol (PVA) films with differently shaped inverted-pyramid texture were fabricated by a simple transferring imprint approach, and their effects on light extraction of OLED were studied. We found out that the light extraction was affected mainly by the inclination angle rather than size of inverted-pyramid, which was explained by the classic ray theory as well. Besides, the textured film brought hardly changed emission spectrum and wider viewing angle of the OLED.