Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Light extraction from surface plasmons and waveguide modes in an organic light-emitting layer by nanoimprinted gratings

Open Access Open Access

Abstract

Organic light-emitting diodes (OLEDs) usually exhibit a low light outcoupling efficiency because a large fraction of power is lost to surface plasmons (SPs) and waveguide modes. In this paper it is demonstrated that periodic grating structures with almost µm-scale can be used to extract SPs as well as waveguide modes and therefore enhance the outcoupling efficiency in light-emitting thin film structures. The gratings are fabricated by nanoimprint lithography using a commercially available diffraction grating as a mold which is pressed into a polymer resist. The outcoupling of SPs and waveguide modes is detected in fluorescent organic films adjacent to a thin metal layer in angular dependent photoluminescence measurements. Scattering up to 5th-order is observed and the extracted modes are identified by comparison to the SP and waveguide dispersion obtained from optical simulations. In order to demonstrate the low-cost, high quality and large area applicability of grating structures in optoelectronic devices, we also present SP extraction using a grating structure fabricated by a common DVD stamp.

©2010 Optical Society of America

Full Article  |  PDF Article
More Like This
Corrugated organic light-emitting diodes to effectively extract internal modes

Haowen Liang, Hao-Chun Hsu, Jiangning Wu, Xiaofeng He, Mao-Kuo Wei, Tien-Lung Chiu, Chi-Feng Lin, Jiu-Haw Lee, and Jiahui Wang
Opt. Express 27(8) A372-A384 (2019)

Light extraction from surface plasmon polaritons and substrate/waveguide modes in organic light-emitting devices with silver-nanomesh electrodes

Minji Hwang, Chanho Kim, Hyekyung Choi, Heeyeop Chae, and Sung Min Cho
Opt. Express 24(26) 29483-29495 (2016)

Extraction of surface plasmons in organic light-emitting diodes via high-index coupling

Bert J. Scholz, Jörg Frischeisen, Arndt Jaeger, Daniel S. Setz, Thilo C. g. Reusch, and Wolfgang Brütting
Opt. Express 20(S2) A205-A212 (2012)

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (12)

Fig. 1
Fig. 1 (a) Schematic dispersion of light and surface plasmons in a sample with planar interfaces. (b) Dispersion in a sample with periodically corrugated interfaces. In the latter case scattering of surface plasmons at the periodic grating may occur which shifts the SP wave vector by a multiple of the grating wave vector.
Fig. 2
Fig. 2 (a) Illustration of imprint lithography and sample fabrication: The corrugation of the master stamp is transferred to a heated sample consisting of a PMMA layer on glass, producing a replica of the grating. In the last step, organic and metallic layers are evaporated on the PMMA grating. (b) Device overview: Devices 1 and 2 are based on the same grating with 833 nm period but employ a different Alq3 thickness. In addition, a half cylinder fused silica prism is attached to the backside of device 1. Device 3 uses a 740 nm grating from a DVD stamp which is directly imprinted into the active layer (5 wt% Lumogen Yellow doped into PMMA).
Fig. 3
Fig. 3 Experimental setup (top view). A half cylinder fused silica prism is attached to the backside of device 1 whereas devices 2 and 3 are measured without additional outcoupling structure.
Fig. 4
Fig. 4 (a), (b) Simulation of the total dissipated power for devices 1 and 2, respectively, without taking the corrugation into account. The emitter position is assumed to be centered in the Alq3 layer. Red areas indicate high amount of dissipated power. The solid white lines divide the graph into four regions: emission into air (1), emission into glass substrate (2), waveguide modes (3) and coupling to surface plasmons (4). No waveguide modes exist in device 1 due to the thin Alq3 layer. The dashed yellow line was calculated using Eq. (1) assuming semi-infinite Ag and Alq3 layers.
Fig. 5
Fig. 5 (a) AFM image of the structure obtained by imprint of a grating with 833 nm period into PMMA as used in devices 1 and 2. (b) Profile at the position indicated by the dotted line in (a).
Fig. 6
Fig. 6 SEM cross section image of device 2.
Fig. 7
Fig. 7 Measurement of the p-polarized emission of device 1. The dotted lines represent the dispersion of surface plasmons obtained from Fig. 4(a) shifted by a multiple m of the wave vector of an 833 nm grating. Negative values of m denote scattering of surface plasmons traveling in the positive k x-direction and vice versa. The higher emission around −47° results from reflections of the incident laser beam. The two horizontal dashed lines indicate the position of the cross sections shown in Fig. 8.
Fig. 8
Fig. 8 (a), (b) Cross section of Fig. 7 at a wavelength of 575 nm and 625 nm, respectively. The dotted lines approximately indicate the contribution of directly emitted light. The increased intensity around −47° due to the reflected laser has been manually subtracted.
Fig. 9
Fig. 9 Measured p-polarized emission of device 2. The lines are obtained from the dispersion of surface plasmons shown in Fig. 4(b) shifted by a multiple of the wave vector of an 833 nm grating.
Fig. 10
Fig. 10 Measured s-polarized emission of device 2. The lines are obtained from the dispersion of the waveguide mode shown in Fig. 4(b) shifted by a multiple of the wave vector of an 833 nm grating.
Fig. 11
Fig. 11 (a) AFM image after imprinting a DVD stamp into the Lumogen:PMMA layer used in device 3. The DVD track runs diagonally from the top right to the bottom left corner. (b) Profile at the position indicated by the dotted line in (a).
Fig. 12
Fig. 12 Measurement of the p-polarized emission of device 3. The lines represent the SP dispersion obtained from a simulation of device 3 shifted by a multiple of the wave vector of a 740 nm grating which corresponds to the track pitch of a DVD.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

k S P = k 0 ε m ε d ε m + ε d ,
k S P = k S P ± m k g ,
Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved