Efficiency improvement and spectral shift of an organic light-emitting device with a square-based microlens array

OPTICS COMMUNICATIONS

卷:281

Article

Wei, Mao-Kuo¹  Lin, Hoang-Yan²  Lee, Jiun-Haw²  Chen, Kuan-Yu²  Ho, Yu-Hsuan²  Lin, Ciao-Ci¹  Wu, Chia-Fang²  Lin, Hung-Yi³  Tsai, Jen-Hui³  Wu, Tung-Chuan³ 

[1] Natl Dong Hwa Univ, Dept Mat Sci & Engn, Inst Optoelect Engn, Hualien 974, Taiwan

[2] Natl Taiwan Univ, Dept Elect Engn, Grad Inst Photon & Optoelect, Taipei 106, Taiwan

[3] Ind Technol Res Inst, Mech & Syst Res Labs, Hsinchu 310, Taiwan

关键词: Microlens;    Organic light-emitting device;    Luminous current efficiency;    Luminous power efficiency;    Fill factor;    Height ratio;   

DOI  :  10.1016/j.optcom.2008.07.087

来源: Elsevier

【 摘 要 】

In this paper, we present and analyze the influences of the fill factor and the height ratio of square-based microlens arrays on the optical characteristics of an organic light-emitting device (OLED). These properties include spectral shift, CIE coordinates, viewing-angle dependence, luminous current efficiency and luminous power efficiency. Both the luminous current efficiency and luminous power efficiency of the OILED were found to increase linearly with increasing the fill factor of microlenses. It is also found that the full width at half maximum (FWHM) of the OLED spectra and CIE coordinate decreased linearly with increasing the fill factor of the microlenses. Besides, the efficiency improvement of the OLED increased with the height ratio of attached microlenses. Compared to the OLED, the luminous current efficiency and luminous power efficiency of the device can be enhanced by 42% and 47%, respectively, by attaching the microlens array having a fill factor of 90% and a height ratio of 0.57. We also observed blue shifts at different viewing angles when microlens arrays were attached to the OLED, which is the evidence that the waveguiding modes are being extracted. In our planar OLED, the peak wavelength blue shifted and the FWHM decreased with increasing the viewing angles due to the microcavity effect. (c) 2008 Elsevier B.V. All rights reserved.

【 授权许可】

Free