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Proceedings Paper

Fabrication of a three-dimensional nanoporous polymer film as a diffuser for microcavity OLEDs
Author(s): Beom Pyo; Ye Ram Cho; Min Chul Suh
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Paper Abstract

We used a nanoporous polymer film prepared by cellulose acetate butyrate with ~40% of optical haze value as a diffuser. It was fabricated by a simple spin-coating process during continuous water mist supply by a humidifier. The pores were created by the elastic bouncing mechanism (rather than the thermocapillary convection mechanism) of the supplied water droplets. The shapes and sizes of the caves formed near the polymer surface are randomly distributed, with a relatively narrow pore size distribution (300–500 nm). Specifically, we focused on controlling the surface morphology to give a three-dimensional (3D) multi-stacked nanocave structure because we had already learnt that two-dimensional nanoporous structures showed serious loss of luminance in the forward direction. Using this approach, we found that the 3D nanoporous polymer film can effectively reduce the viewing angle dependency of strong microcavity OLEDs without any considerable decrease in the total intensity of the out-coupled light. We applied this nanoporous polymer film to microcavity OLEDs to investigate the possibility of using it as a diffuser layer. The resulting nanoporous polymer film effectively reduced the viewing angle dependency of the microcavity OLEDs, although a pixel blurring phenomenon occurred. Despite its negative effects, such as the drop in efficiency in the forward direction and the pixel blurring, the introduction of a nanoporous polymer film as a scattering medium on the back side of the glass substrate eliminated the viewing angle dependency. Thus, this approach is a promising method to overcome the serious drawbacks of microcavity OLEDs.

Paper Details

Date Published: 22 September 2015
PDF: 9 pages
Proc. SPIE 9566, Organic Light Emitting Materials and Devices XIX, 95661F (22 September 2015); doi: 10.1117/12.2187703
Show Author Affiliations
Beom Pyo, Kyung Hee Univ. (Korea, Republic of)
Ye Ram Cho, Kyung Hee Univ. (Korea, Republic of)
Min Chul Suh, Kyung Hee Univ. (Korea, Republic of)

Published in SPIE Proceedings Vol. 9566:
Organic Light Emitting Materials and Devices XIX
Franky So; Chihaya Adachi; Jang-Joo Kim, Editor(s)

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