Title: Directional out-coupling efficiency enhancement of organic light-emitting devices by a microlens array

Authors: Su Shen; Fang Zhou; Guojun Wei; Donglin Pu; Yun Zhou

Addresses: Institute of Information Optical Engineering, Soochow University, Shizi Street 1#, Suzhou, 215006, China ' Institute of Information Optical Engineering, Soochow University, Shizi Street 1#, Suzhou, 215006, China ' Institute of Information Optical Engineering, Soochow University, Shizi Street 1#, Suzhou, 215006, China ' Institute of Information Optical Engineering, Soochow University, Shizi Street 1#, Suzhou, 215006, China ' Institute of Information Optical Engineering, Soochow University, Shizi Street 1#, Suzhou, 215006, China

Abstract: Microlens arrays film fabricated by ultra-violet (UV) roll-to-roll nanoimprinting lithography is introduced on glass substrate to directionally coupling the efficiency of organic light-emitting devices (OLEDs). The microlenses suppress wave guiding loss in the substrate and a theoretical model, based on Monte-Carlo model, is developed to simulate the enhancement effects. The numerical results show that ellipsoidal-like microlens array can not only increase the efficiency by a factor of more than 35%, but also directionally couple output light with the luminance density distribution along the orthogonal directions compressed by 10 degrees. Such a microlens array mould is fabricated by a combination of DMD-based laser direct writing lithography and thermal reflow method, followed by electroforming for transferring the surface structure to a nickel plate. The obtained mould is wrapped on a roller for the mass production of microlens array film by UV roll-to-roll nanoimprinting process. OLED attached with such microlens array film with a maximum increase of 35% in efficiency is achieved and directional out-coupling phenomenon can be observed experimentally. Such a directional out-coupling microlens array film can be used in OLED to enhance the luminous intensity efficiency and save power consumption for future lighting and display application.

Keywords: microlens arrays; R2R; roll-to-roll nanoimprinting; OLED; directional out-coupling; organic light-emitting devices; glass substrate; Monte Carlo simulation; modelling; luminous intensity; power consumption.

DOI: 10.1504/IJNM.2013.057597

International Journal of Nanomanufacturing, 2013 Vol.9 No.5/6, pp.532 - 539

Received: 27 Oct 2012
Accepted: 26 Mar 2013
Published online: 31 Mar 2014 *

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