Open AccessMicroporous phase-separated films of polymer blends for enhanced outcoupling of light from OLEDs
Author(s) -
Rui Li,
Zhuo Ye,
Joong-Mok Park,
Min Cai,
Ying Chen,
KaiMing Ho,
Ruth Shinar,
J. Shinar
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.0a1272
Subject(s) - materials science , oled , polystyrene , substrate (aquarium) , microlens , thin film , microporous material , optics , optoelectronics , refractive index , fabrication , phase (matter) , polymer , pinhole (optics) , nanotechnology , composite material , layer (electronics) , lens (geology) , medicine , oceanography , physics , alternative medicine , organic chemistry , chemistry , pathology , geology
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 ~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.