Special Section on Organic Light-Emitting Materials and Devices

Enhancing light extraction in organic light-emitting devices via hemispherical microlens arrays fabricated by soft lithography

[+] Author Affiliations
Sang-Hyun Eom

University of Florida, Department of Materials Science and Engineering, Gainesville, Florida 32611-6400

Edward Wrzesniewski

University of Florida, Department of Materials Science and Engineering, Gainesville, Florida 32611-6400

Jiangeng Xue

University of Florida, Department of Materials Science and Engineering, Gainesville, Florida 32611-6400

J. Photon. Energy. 1(1), 011002 (January 04, 2011). doi:10.1117/1.3528267
History: Received August 27, 2010; Revised November 10, 2010; Accepted November 15, 2010; Published January 04, 2011; Online January 04, 2011
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We demonstrate enhanced light extraction in organic light-emitting devices (OLEDs) by using microlens arrays fabricated by a soft lithography technique. A large-area and close-packed polystyrene (PS) monolayer was formed on the SiO2 substrate using a convective-capillary assembly method, and a polydimethylsiloxane polymer was used to obtain a concave template, from which microlens arrays were fabricated from a photopolymerizable transparent optical adhesive. The microlens contact angle and array fill factor both depend on the size of PS microspheres, and nearly close-packed, hemispherical microlens arrays with microlens contact angle of (85 ± 5 deg) and array fill factor of (85 ± 3)% were obtained with 100-μm PS microspheres. The enhancement in the light-extraction efficiency in OLEDs when such fabricated microlens arrays were attached to the light-emitting surface depends on the contact angle of microlens, device size, and detailed multilayer structure of the OLED. For a large-area (12 × 12 mm) fluorescent OLED with a near close-packed hemispherical microlens array, a maximum enhancement of (70 ± 7)% in the light-extraction efficiency was achieved.

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© 2011 Society of Photo-Optical Instrumentation Engineers

Citation

Sang-Hyun Eom ; Edward Wrzesniewski and Jiangeng Xue
"Enhancing light extraction in organic light-emitting devices via hemispherical microlens arrays fabricated by soft lithography", J. Photon. Energy. 1(1), 011002 (January 04, 2011). ; http://dx.doi.org/10.1117/1.3528267


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