Organic light-emitting diodes (OLEDs): Materials, photophysics, and device physics

Chihaya Adachi, Saeyoun Lee, Tetsuya Nakagawa, Katsuyuki Shizu, Kenichi Goushi, Takuma Yasuda, William J. Potscavage

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

11 Scopus citations

Abstract

Currently, organic light-emitting diodes (OLEDs) have reached the stage of commercialization, and there has been an intense drive to use them in various applications from small-and medium-sized mobile devices to illumination equipment and large television screens. In particular, room-temperature phosphorescent materials have become core OLED components as alternatives to conventionally used fluorescent materials because devices made with phosphorescent materials exhibit excellent light-emitting performance with internal electroluminescence efficiencies (ηint) of nearly 100 %. However, phosphorescent materials have several intrinsic problems, such as being limited to metal-organic compounds containing rare metals, for example, Ir, Pt, Au, and Os, and difficulty in realizing stable blue light emission. As a result, researchers have attempted to develop new materials for use as emissive dopants in OLEDs that overcome these limitations. In this chapter, first we briefly review the progress of OLED materials and device architectures mainly based on fluorescent (first-generation) and phosphorescent (secondgeneration) emitters. Then, we discuss third-generation OLEDs that use a new light-emitting mechanism called thermally activated delayed fluorescence (TADF). Recently, highly efficient TADF, which had been difficult to realize with conventional molecular design, has been achieved by very sophisticated molecular structures, allowing access to the unlimited freedom of molecular design using carbon-based materials. This has led to the production of ultimate OLEDs that are made of common organic compounds without precious metals and can convert electricity to light at ηint of nearly 100 %.

Original languageEnglish
Title of host publicationOrganic Electronics Materials and Devices
PublisherSpringer Japan
Pages43-73
Number of pages31
ISBN (Electronic)9784431556541
ISBN (Print)9784431556534
DOIs
StatePublished - 18 Sep 2015

Keywords

  • Electroluminescence
  • OLED
  • TADF

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