Abstract

In this paper, we report bright, efficient Alq3-based [tris-(8-hydroxyquinoline) aluminum] organic light-emitting diode (OLED) structures that incorporate hemispherical lenses for increased output power efficiency. The 6-layer hybrid (polymer/small molecule) OLED structure contains two spin-coated polymer layers and four thermally evaporated small molecule layers. This structure results in balanced charge injection, thus leading to a more efficient device. The use of index-matched transparent lenses resulted in luminous and external quantum efficiency of 7.5 lm/W and 8%, respectively. The size and shape of the lens was used to control the angular power distribution. Lenses incorporating color conversion media were used to achieve high OLED efficiency in various colors. Saturated yellow, orange, and red devices with external quantum efficiencies as high ~4 were obtained from this approach.

© 2006 IEEE

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J. Display Technol. (1)

E. H-E. Wu, S.-H. Li, C.-W. Chen, G. Li, Z. Xu, Y. Yang, "Controlling optical properties of electrodes with stacked metallic thin films for polymeric light-emitting diodes and displays," J. Display Technol. 1, 105-111 (2005).

Adv. Mater. (5)

J. Cui, Q. Huang, J. G. C. Veinot, H. Yan, T. J. Marks, "Interfacial microstructure function in organic light-emitting diodes: assembled tetraaryldiamine and copper phthalocyanine," Adv. Mater. 14, 565-569 (2002).

N. C. Greenham, R. H. Friend, D. D. C. Bradley, "Angular dependence of the emission from a conjugated polymer light-emitting diode: implications for efficiency calculations," Adv. Mater. 6, 491-494 (1994).

T. Tsutsui, M. Yahiro, H. Yokogawa, K. Kawano, M. Yokoyama, "Doubling coupling-out efficiency in organic light-emitting devices using a thin silica aerogel layer," Adv. Mater. 13, 1149-1152 (2001).

S. R. Forrest, D. D. C. Bradley, M. E. Thompson, "Measuring the efficiency of organic light-emitting devices," Adv. Mater. 15, 1043-1048 (2003).

D. F. O'Brien, P. E. Burrows, S. R. Forrest, B. E. Koene, D. E. Loy, M. E. Thompson, "Hole transporting materials with high glass transition temperatures for use in organic light-emitting devices," Adv. Mater. 10, 1108-1112 (1998).

Appl. Phys. Lett. (4)

Q. Huang, J. Cui, J. G. C. Veinot, H. Yan, T. J. Marks, "Realization of high-efficiency/high-luminance small-molecule organic light-emitting diodes: synergistic effects of siloxane anode functionalization/hole-injection layers, and hole/exciton-blocking/electron-transport," Appl. Phys. Lett. 82, 331-333 (2003).

S. Naka, H. Okada, H. Onnagawa, T. Tsutsui, "High electron mobility in bathophenanthroline," Appl. Phys. Lett. 76, 197-199 (2000).

A. R. Duggal, J. J. Shiang, C. M. Heller, D. F. Foust, "Organic light-emitting devices for illumination quality white light," Appl. Phys. Lett. 80, 3470-3472 (2002).

C. W. Tang, S. A. VanSlyke, "Organic electroluminescent diodes," Appl. Phys. Lett. 51, 913-915 (1987).

Appl. Phys. Lett. (1)

E. I. Haskal, A. Curioni, P. F. Seidler, W. Andreoni, "Lithium-aluminum contacts for organic light-emitting devices," Appl. Phys. Lett. 71, 1151-1153 (1997).

Appl. Phys. A (1)

S. Wang, Y. Q. Liu, X. B. Huang, S. L. Xu, J. R. Gong, X. H. Chen, L. Yi, Y. Xu, G. Yu, L. J. Wan, C. L. Bai, D. B. Zhu, "Organic light-emitting diodes with improved hole-electron balance by using molecular layers of phthalocyanine to modify the anode surface," Appl. Phys. A 78, 553-556 (2004).

Appl. Phys. Lett. (6)

B. J. Chen, W. Y. Lai, Z. Q. Gao, C. S. Lee, S. T. Lee, W. A. Gambling, "Electron drift mobility and electroluminescent efficiency of tris(8-hydroxyquinolinolato) aluminum," Appl. Phys. Lett. 75, 4010-4012 (1999).

S. T. Lee, Y. M. Wang, X. Y. Houb, "Interfacial electronic structures in an organic light-emitting diode," Appl. Phys. Lett. 74, 670-672 (1999).

X. Y. Deng, S. W. Tong, L. S. Hung, Y. Q. Mo, Y. Cao, "Role of ultrathin Alq3 and LiF layers in conjugated polymer light-emitting diodes," Appl. Phys. Lett. 82, 3104-3106 (2003).

T. Kanbara, T. Yamamoto, K. Ishikawa, H. Takezoe, A. Fukuda, "Polyquinoxaline as an excellent electron injecting material for electroluminescent device," Appl. Phys. Lett. 68, 2346-2348 (1996).

C. F. Madigan, M. H. Lu, J. C. Sturm, "Improvement of output coupling efficiency of organic light-emitting diodes by backside substrate modification," Appl. Phys. Lett. 76, 1650-1652 (2000).

T. Yamasaki, K. Sumioka, T. Tsutsui, "Organic light-emitting device with an ordered monolayer of silica microspheres as a scattering medium," Appl. Phys. Lett. 76, 1243-1245 (2000).

Appl. Surf. Sci. (1)

T. Mori, T. Ogawa, D. Cho, T. Mizutani, "A discussion of conduction in organic light-emitting diodes," Appl. Surf. Sci. 212-213, 458-463 (2003).

Chem. Rev (1)

S. R. Forrest, "Ultrathin organic films grown by organic molecular beam deposition and related techniques," Chem. Rev 97, 1793-1896 (1997).

Dyes and Pigments (1)

G. Seybold, G. Wagenblast, "New perylene and violanthrone dyestuffs for fluorescent collectors," Dyes and Pigments 11, 303-317 (1989).

Eur. Phys. J. B (1)

L. A Zuppiroli, L. Si-Ahmed, K. Kamaras, F. Nuesch, M. N. Bussac, D. Ades, A. Siove, E. Moons, M. Gratzel, "Self-assembled monolayers as interfaces for organic opto-electronic devices," Eur. Phys. J. B 11, 505-512 (1999).

IEEE Trans. Electron Devices (1)

P. E. Burrows, G. Gu, V. Bulovic, Z. Shen, S. R. Forrest, M. E. Thompson, "Achieving full-color organic light-emitting devices for lightweight, flat-panel displays," IEEE Trans. Electron Devices 44, 1188-1203 (1997).

J. Appl. Phys. (6)

G. Parthasarathy, C. Shen, A. Kahn, S. R. Forrest, "Lithium doping of semiconducting organic charge transport materials," J. Appl. Phys. 89, 4986-4992 (2001).

P. E. Burrows, Z. Shen, V. Bulovic, D. M. McCarty, S. R. Forrest, J. A. Cronin, M. E. Thompson, "Relationship between electroluminescence and current transport in organic heterojunction light-emitting devices," J. Appl. Phys. 79, 7991-8006 (1996).

C. W. Tang, S. A. VanSlyke, C. H. Chen, "Electroluminescence of doped organic thin films," J. Appl. Phys. 65, 3610-3616 (1989).

Y. Yang, Q. Pei, "Electron injection polymer for polymer light-emitting diodes," J. Appl. Phys. 77, 4807-4809 (1994).

M. G. Mason, C. W. Tang, L. S. Hung, P. Raychaudhuri, J. Madathil, D. J. Giesen, L. Yan, Q. T. Le, Y. Gao, S. Y. Lee, L. S. Liao, L. F. Cheng, W. R. Salaneck, D. A. d. Santos, J. L. Bredas, "Interfacial chemistry of Alq3 and LiF with reactive metals," J. Appl. Phys. 89, 2756-2765 (2001).

G. E. Jabbour, M. M. Morrell, Y. Kawabe, B. Kippelen, N. Peyghambarian, M.-F. Nabor, R. Schlaf, E. A. Mash, N. R. Armstrong, "Bright blue organic light-emitting diode with improved color purity using a LiF/Al cathode," J. Appl. Phys. 84, 2324-2327 (1998).

J. Disp. Technol. (1)

S. W. Wen, M. T. Lee, C. H. Chen, "Recent development of blue fluorescent OLED materials and devices," J. Disp. Technol. 1, 90-99 (2005).

J. Display Technol. (1)

Mol. Cryst. Liq. Cryst. (1)

S. Kim, D. Chung, J. Hong, T. Chung, T. Kim, W. Lee, K. Jang, "Effects of buffer layer in organic light-emitting diodes," Mol. Cryst. Liq. Cryst. 377, 129-132 (2002).

Nature (1)

M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E. Thompson, S. R. Forrest, "Highly efficient phosphorescent emission from organic electroluminescent devices," Nature 395, 151-154 (1998).

Opt. Lett. (1)

Org. Electron. (1)

K. Book, H. Bassler, A. Elschner, S. Kirchmeyer, "Hole injection from an ITO/PEDT anode into the hole transporting layer of an OLED probed by bias induced absorption," Org. Electron. 4, 227-232 (2003).

Phys. Rev. B (1)

V. Bulovic, V. B. Khalfin, G. Gu, P. E. Burrows, D. Z. Garbuzov, S. R. Forrest, "Weak microcavity effects in organic light-emitting devices," Phys. Rev. B 58, 3730-3740 (1998).

Pure Appl. Chem. (1)

M. A. Baldo, M. E. Thompson, S. R. Forrest, "Phosphorescent materials for application to organic light emitting devices," Pure Appl. Chem. 71, 2095-2106 (1999).

Pure Appl. Chem. (1)

G. E. Johnson, K. M. McGrane, M. Stolka, "Electroluminescence from single layer molecularly doped polymer films," Pure Appl. Chem. 67, 175-182 (1995).

Science (1)

J. R. Sheats, H. Antoniadis, M. Heuschen, W. Leonard, J. Miller, R. Moon, D. Roitman, A. Shocking, "Organic electroluminescent devices," Science 273, 884-887 (1996).

Synth. Met. (2)

T. J. Marks, J. G. C. Veinot, J. Cui, H. Yan, A. Wang, N. L. Edleman, J. Ni, Q. Huang, P. Lee, N. R. Armstrong, "Progress in high work function TCO OLED anode alternatives and OLED nanopixelation," Synth. Met. 127, 29-35 (2002).

S. Naka, H. Okada, H. Onnagawa, Y. Yamaguchi, T. Tsutsui, "Carrier transport properties of organic materials for EL device operation," Synth. Met. 111-112, 331-333 (2000).

Thin Solid Films (1)

T. Kugler, W. R. Salaneck, "Characterization of the PEDOT-PSS system by means of X-ray and ultraviolet photoelectron spectroscopy," Thin Solid Films 354, 129-135 (1999).

Other (1)

H. Fujikawa, M. Ishii, S. Tokito, Y. Taga, "Organic light-emitting diodes using triphenylamine based hole transporting materials," Proc. Mat. Res. Soc. Symp. (2000).

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