Microporous phase-separated films of polymer blends for enhanced outcoupling of light from OLEDs

TitleMicroporous phase-separated films of polymer blends for enhanced outcoupling of light from OLEDs
Publication TypeJournal Article
Year of Publication2011
AuthorsLiu R, Ye Z, Park JM, Cai M, Chen Y, Ho KM, Shinar R, Shinar J
Journal TitleOptics Express
Volume19
PagesA1272-A1280
Date Published11
Type of ArticleArticle
ISBN Number1094-4087
Accession NumberWOS:000296904700013
Keywordsconcave, coupling efficiency, devices, emitting-diodes, extraction, improvement, microlens arrays
Abstract

Thin microporous films were formed by dropcasting a toluene solution containing various ratios of polystyrene: polyethylene glycol blends on a glass substrate, with OLEDs on the ITO that coated the opposite side of that substrate. We demonstrate for the first time that such easily-fabricated films with surface and bulk micropores in the index-matching polystyrene can serve as random microlens-like arrays to improve forward OLED light extraction by up to similar to 60%. A theoretical interpretation of the angular emission profile of the device, considering the geometrical change at the substrate/air interface and the scattering by the pores within the films, was established in excellent agreement with the experiments. The use of such blended thin films provides an economical method, independent of the OLED fabrication technique, for improving the outcoupling efficiency. (C) 2010 Optical Society of America

DOI10.1364/OE.19.0A1272
Alternate JournalOpt. Express