1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
f
Enhanced light extraction in organic light-emitting devices: Using conductive low-index layers and micropatterned indium tin oxide electrodes with optimal taper angle
Rent:
Rent this article for
Access full text Article
/content/aip/journal/apl/100/23/10.1063/1.4724306
1.
1. C. Adachi, M. A. Baldo, M. E. Thompson, and S. R. Forrest, J. Appl. Phys. 90, 5048 (2001).
http://dx.doi.org/10.1063/1.1409582
2.
2. Y. Sun, N. C. Giebink, H. Kanno1, B. Ma, M. E. Thompson, and S. R. Forrest, Nature 440, 908 (2006).
http://dx.doi.org/10.1038/nature04645
3.
3. J. Kim, P. K. H. Ho, N. C. Greenham, and R. H. Friend, J. Appl. Phys. 88, 1073 (2000).
http://dx.doi.org/10.1063/1.373779
4.
4. R. Meerheim, M. Furno, S. Hofmann, B. Lüssem, and K. Leo, Appl. Phys. Lett. 97, 253305 (2010).
http://dx.doi.org/10.1063/1.3527936
5.
5. S.-Y. Kim and J.-J. Kim, Org. Electron. 11, 1010 (2010).
http://dx.doi.org/10.1016/j.orgel.2010.03.023
6.
6. Y. Sun and S. R. Forrest, Nat. Photonics 2, 483 (2008).
http://dx.doi.org/10.1038/nphoton.2008.132
7.
7. W. H. Koo, S. M. Jeong, F. Araoka, K. Ishikawa, S. Nishimura, T. Toyooka, and H. Takezoe, Nat. Photonics 4, 222 (2010).
http://dx.doi.org/10.1038/nphoton.2010.7
8.
8. S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, and K. Leo, Nature 459, 234 (2009).
http://dx.doi.org/10.1038/nature08003
9.
9. K. Hong and J.-L. Lee, Electron. Mater. Lett. 7, 77 (2011).
http://dx.doi.org/10.1007/s13391-011-0601-1
10.
10. T.-W. Koh, J. Choi, S. Lee, and S. Yoo, Adv. Mater. 22, 1849 (2010).
http://dx.doi.org/10.1002/adma.200903375
11.
11. K. Fehse, K. Walzer, K. Leo, W. Lövenich, and A. Elschner, Adv. Mater. 19, 441 (2007).
http://dx.doi.org/10.1002/adma.200602156
12.
12. J. S. Kim, P. K. H. Ho, D. S. Thomas, R. H. Friend, F. Cacialli, G. W. Bao, and S. F. Y. Li, Chem. Phys. Lett. 315, 307 (1999).
http://dx.doi.org/10.1016/S0009-2614(99)01233-6
13.
13. D. Z. Garbuzov, V. B. Bulović, P. E. Burrows, and S. R. Forrest, Chem. Phys. Lett. 249, 433 (1996).
http://dx.doi.org/10.1016/0009-2614(95)01424-1
14.
14. T. Gerfin, and M. Grätzel, J. Appl. Phys. 79, 1729 (1996); also see SOPRA n&k database.
http://dx.doi.org/10.1063/1.360960
15.
15. S. Franssila, Introduction to Microfabrication (Wiley, West Sussex, UK, 2004), Chap. 11.
16.
16.Product data sheet, AZ 5214E Image Reversal Photoresist, Clariant Corp, Somerville, NJ, 1990.
17.
17.There is also an electrical artifact due to a noise being amplified when L < 100–200 cd/m2.
18.
journal-id:
http://aip.metastore.ingenta.com/content/aip/journal/apl/100/23/10.1063/1.4724306
Loading
View: Figures

Figures

Image of FIG. 1.

Click to view

FIG. 1.

(a) Top-view diagram of the bilayer anode structures under study (left: square lattice; right: hexagonal lattice) and (b) cross-sectional diagram (along the line A-A′) of an OLED containing them. Three representative ray diagrams are shown to illustrate the working principle of the proposed structure.

Image of FIG. 2.

Click to view

FIG. 2.

Optical simulation results for OLEDs with the proposed anode structure: (a) η out vs. taper angle (θt ) for square and hexagonal lattice geometries with or without absorption from ITO or organic layers assumed; (b) η out vs. absorption coefficient of ITO (α ITO) or organic (α org) layers; (c) η out vs. spatial period (a) with d/a of 0.5. Also shown is the curve for diffraction efficiency (η diff) vs. a. (1D grating assumed for simplicity.); (d) η out vs. d/a with a of 6 μm. Separate contributions of the light originating from region P and region I/P, respectively, are also shown. The following assumptions were used in (a)-(d) unless specified otherwise θt  = 45°; hexagonal lattice (a = 6 μm, d/a = 0.5); α ITO = 1.1 × 104 cm−1; and α org = 1.0 × 103 cm−1.

Image of FIG. 3.

Click to view

FIG. 3.

(a) Overall process flow for fabrication of OLEDs based on the proposed anode structure of which the ITO pattern edge has the optimal taper angle. (b) The cross-sectional SEM images of the inverse trapezoidal structure created with negative photoresist (PR) and (c) that of the sputtered ITO pattern defined by the proposed lift-off process.

Image of FIG. 4.

Click to view

FIG. 4.

Experimental results for (a) EQE and (b) PE vs. luminance of OLEDs under study. OLED devices are in the structure of glass/x/NPB (50 nm)/Alq3 (50 nm)/LiF (1 nm)/Al with x being (i) planar ITO without PEDOT:PSS (= “reference”) or (ii) patterned ITO covered with PEDOT:PSS (= “CLIL”).

Loading

Article metrics loading...

/content/aip/journal/apl/100/23/10.1063/1.4724306
2012-06-05
2014-04-19

Abstract

We present our study on organic light-emitting diodes(OLEDs) in which outcoupling is enhanced based on a bilayer electrode consisting of a conductive low-index layer and micro-patterned indiumtin oxide (ITO) layers. Optical simulation reveals that the taper angle of an ITO pattern is among the most critical parameters influencing the outcoupling efficiency in the proposed structure. A fabrication method based on a lift-off process is then employed to control the taper angle of the ITO pattern to be in the optimal range. OLEDs with the proposed electrodestructure exhibit 50%–70% enhancement in external quantum efficiency over reference devices.

Loading

Full text loading...

/deliver/fulltext/aip/journal/apl/100/23/1.4724306.html;jsessionid=djg2t3r5314n.x-aip-live-01?itemId=/content/aip/journal/apl/100/23/10.1063/1.4724306&mimeType=html&fmt=ahah&containerItemId=content/aip/journal/apl
true
true
This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Enhanced light extraction in organic light-emitting devices: Using conductive low-index layers and micropatterned indium tin oxide electrodes with optimal taper angle
http://aip.metastore.ingenta.com/content/aip/journal/apl/100/23/10.1063/1.4724306
10.1063/1.4724306
SEARCH_EXPAND_ITEM