Recent advances in organic luminescent materials with narrowband emission

Abstract

The International Telecommunication Union announced a new color gamut standard of broadcast service television (BT 2020) for ultra-high-definition TV in 2012. To satisfy the wide-color gamut standard of BT 2020, monochromatic red (R), green (G), and blue (B) emissions require a small full width at half-maximum, which is an important property for improving color purity. Although organic light-emitting diode (OLED) displays are currently one of the main types of display technologies, their broad emission via strong vibronic coupling between ground and excited states is a major hurdle to overcome in the development of next-generation wide-color gamut displays. Thus, the development of OLED emitters with narrowband R–G–B emissions is of great significance. In this review, the recent progress in the development of OLED materials with narrowband emission is summarized by grouping them into fluorescent, phosphorescent, and thermally activated delayed fluorescent emitters to reveal the correlation between molecular structures, optical properties, and device characteristics. We discuss rational molecular design strategies to achieve narrow photoluminescence and electroluminescence and the underlying mechanisms for controlling the emission bandwidth. Finally, the challenges in the realization of wide-color gamut OLED displays and the future prospects of such devices are discussed.

Optoelectronics: An organic route to higher optical purity

Organic light-emitting diodes (OLEDs) with high color purity could be used in the next generation of high-definition televisions. The most widely used semiconductor, silicon, is an inorganic material but a wide range of organic alternatives are now emerging. These alternatives are especially in demand for light-emitting applications, where the performance of silicon is poor. Ji-Eun Jeong, Han Young Woo and colleagues from Korea University in Seoul, South Korea, reviewed recent progress in the development of OLEDs. An OLED tends to emit light over a relatively broad spectrum. This lack of color purity limits the device’s use in future ultra-high-definition TVs. The team presented an overview of the various molecular design strategies that have been used to reduce emission bandwidth and the physical mechanisms forming the basis of these strategies.

With a growing demand for new emitters to realize ultra-high-definition displays, various types of organic emitters with narrow emission and high luminescent efficiency have been extensively studied. In this review, we summarized the recent developments of organic emitters (fluorescent, phosphorescent, and thermally activated delayed fluorescent) which show narrowband emission spectra with full-width half-maximum smaller than 50 nm.