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.

Efficient circularly polarized thermally activated delayed fluorescence hetero-[4]helicene with carbonyl-/sulfone-bridged triarylamine structures

“…into the helicene skeleton to produce thermally activated delayed fluorescence (TADF) is a promising way of improving the exciton utilization and changing the electronic structure. [23][24][25][26][27][28][29][30][31][32][33][34][35][36] For example, Hatakeyama et al reported an ultrapure blue multiple-resonance thermally activated delayed fluorescence (MR-TADF) molecule with rigid hetero [4]-helicene (DABNA-1, Fig. 1a), which exhibits a high PLQY, a large oscillator strength, a small energy difference (DE ST ) between the lowest excited singlet (S 1 ) and triplet (T 1 ) energies, as well as a high device efficiency.…”

Toward phosphorescent and delayed fluorescent carbon quantum dots for next-generation electroluminescent displays

“…5 Although the color purity of the original broad EL band can be modified by introducing a color filter and/or an optical microcavity in commercial OLED displays, this inevitably leads to a significant increase in cost and power consumption. 81,90 Thus, the development of efficient TADF emitters with narrowband emissions, especially those having the ability to achieve high color purity that complies with the Commission Internationale de L’Eclairage (CIE) coordinates requirements defined by the broadcasting standards, is highly important.…”

Emission and Absorption Tuning in MR-TADF B,N-Doped Hep-tacenes: Towards Ideal-Blue Hyperfluorescent OLEDs

“…11 Multiresonant TADF (MR-TADF) compounds are an alternative class of TADF materials that are typically based on p-and n-doped nanographene (Figure S1). 12,13 Because of their rigid structure, these compounds show narrowband emission, typically with full width of half maxima (FWHM) of around 20-30 nm. Thus, MR-TADF emitters show potential to generate the required deep blue emission demanded by industry, and support the development of stable, efficient, pure blue narrowband emitting organic materials that are expected to revolutionize OLED displays.…”