OLED Displays and Lighting

Mitsuhiro Koden

• Publisher: Wiley-IEEE Press
• Year: 2016
• Print ISBN: 9781119040453
• eBook ISBN: 9781119040484
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Explains the fundamentals and practical applications of flat and flexible OLEDs for displays and lighting

Organic light-emitting diodes (OLEDs) have emerged as the leading technology for the new display and lighting market. OLEDs are solid-state devices composed of thin films of organic molecules that create light with the application of electricity. OLEDs can provide brighter, crisper displays on electronic devices and use less power than conventional light-emitting diodes (LEDs) or liquid crystal displays (LCDs) used today. This book covers both the fundamentals and practical applications of flat and flexible OLEDs.

Key features:

• Covers all of the aspects necessary to the design and manufacturing of OLED displays and lighting.
• Explains the fundamental basic technologies and also related technologies which might contribute to the next innovation in the industry.
• Provides several indications for future innovation in the OLED industry.
• Includes coverage of OLED vacuum deposition type and solution type materials.

The book is essential reading for early career engineers developing OLED devices and OLED related technologies in industrial companies, such as OLED device fabrication companies.

 

 

1
History of OLEDs

Summary

Active research and development of OLEDs (organic light emitting diodes) started in 1987, when Tang and VanSlyke of Eastman Kodak showed that a bright luminance was obtained in an OLED device with two thin organic layers sandwiched between anode and cathode. Since their report, OLEDs have been an attractive field from scientific and practical points of view because OLEDs have great potentials in practical applications such as displays and lighting.

This chapter describes the history of the OLED.

Key words

History, Tang, Kodak, Friend, Forrest, Kido, Adachi

Light emission by organic materials was first discovered in a cellulose film doped with acridine orange by Bernanose et al. in 1953 [1]. Ten years later, in 1963, Pope et al., reported that a single organic crystal of anthracene showed light emission induced by carrier injection in a high electric field [2]. Also, since it became known that a large number of organic materials showed high fluorescent quantum efficiency in the visible spectrum, including the blue region, organic materials have been considered as a candidate for practical light emitting devices. However, early studies did not give any indication of the huge potential of OLEDs because of issues such as very high electric field (e.g. some needing 100 V), very low luminance, and very low efficiency. Therefore OLED studies remained as scientific and theoretical fields, not indicating any great motivation towards practical applications.

A major impact was made by C. W. Tang and S. A. VanSlyke of Eastman Kodak in 1987. They reported a bright emission obtained in an OLED device with two thin organic layers sandwiched between anode and cathode, as shown in Fig. 1.1 [3]. They introduced two innovative technologies, which used very low thicknesses (<150 nm) of organic layers and adoption of a bi‐layer structure. They reported that light emission was observed from as low as about 2.5 V and that high luminance (>1000 cd/m²) was obtained with a dc voltage of less than 10 V. Although the obtained external quantum efficiency (EQE) was still as low as about 1% and the power efficiency was still as little as 1.5 lm/W, the reported results were enough to draw huge attention from scientists and researchers. Indeed, their report started the age of the OLED not only in the academic field but also in industry.

Figure 1.1 The structure and materials of an OLED device reported by Tang et al. [3]

The history of OLEDs is summarized in Table 1.1.

Table 1.1 The history of OLED

1987	Invention of two‐layered OLED with a bright emission (Eastman Kodak / Tang and VanSlyke) [3] (Fig. 1.1)
1990	Invention of polymer OLED (Cavendish Lab. / Burroughes et al. of Friend’s group) [4]
1994	First report of white OLED (Yamagata Univ. / Kido et al.) [5]
1997	World’s first commercial OLED (Pioneer) [6] (Fig. 1.2) (Passive‐matrix monochrome OLED display with bottom emission structure and vacuum deposited small molecular fluorescent materials)
1998	Invention of phosphorescent OLED (Princeton Univ./ Baldo et al. of Thompson and Forrest’s group) [7]
1999	Prototype of a full‐color polymer AM‐OLED display fabricated by ink‐jet printing (Seiko‐Epson) [8]
2001	Prototype 13″ full‐color AM‐OLED display (Sony) [9] (Fig. 1.4)
2002	Invention of multi‐photon OLED (Yamagata Univ./Kido et al.) [10]
	Prototype 17″ full‐color polymer AM‐OLED display fabricated by ink‐jet printing (Toshiba) [11]
2003	World’s first commercial polymer OLED display (Philips) [12]
	World’s first commercial active‐matrix OLED display (SK Display) [13]
2006	Prototype of 3.6″ full‐color polymer AM‐OLED display with the world’s highest resolution (202 ppi) fabricated by ink‐jet printing (Sharp) [14]
2007	World’s first application of AM‐OLED displays for main displays of mobile phones (Samsung) [15]
	World’s first commercial AM‐OLED‐TV (Sony) [16] (Fig. 1.5)
2009	Invention of TADF (thermally activated delayed fluorescence) (Kyushu Univ. / Endo et al. of Adachi’s group) [17]
2010	World’s largest OLED display wit...

Table of contents

• Cover
• Title Page
• Table of Contents
• Preface
• 1 History of OLEDs
• 2 Fundamentals of OLEDs
• 3 Light Emission Mechanism
• 4 OLED Materials
• 5 OLED Devices
• 6 OLED Fabrication Process
• 7 Performance of OLEDs
• 8 OLED Display
• 9 OLED Lighting
• 10 Flexible OLEDs
• 11 New Technologies
• Index
• End User License Agreement