Status and Challenges of Blue OLEDs: A Review

Abstract

Organic light-emitting diodes (OLEDs) have outperformed conventional display technologies in smartphones, smartwatches, tablets, and televisions while gradually growing to cover a sizable fraction of the solid-state lighting industry. Blue emission is a crucial chromatic component for realizing high-quality red, green, blue, and yellow (RGBY) and RGB white display technologies and solid-state lighting sources. For consumer products with desirable lifetimes and efficiency, deep blue emissions with much higher power efficiency and operation time are necessary prerequisites. This article reviews over 700 papers covering various factors, namely, the crucial role of blue emission for full-color displays and solid-state lighting, the performance status of blue OLEDs, and the systematic development of fluorescent, phosphorescent, and thermally activated delayed fluorescence blue emitters. In addition, various challenges concerning deep blue efficiency, lifetime, and approaches to realizing deeper blue emission and higher efficacy for blue OLED devices are also described.

C^C* Platinum(II) Complexes with Bis(pyridyl)borate Ligands: Synthesis, Crystal Structures, and Properties

“…The transition metals iridium(III) − and platinum(II) − are used in phosphorescent complexes as emitting materials for organic light-emitting diodes (OLEDs), − which is a promising technology for displays and illumination devices. , The metal centers in these organometallic compounds can lead to effective spin orbit coupling, allowing for internal luminescence efficiencies of up to 100% for these diodes. − In combination with rigid donor ligands, efficient emitter molecules can be synthesized, because such ligands minimize nonradiative decay processes from the emissive state and therefore reduce the accessibility of unfavorable metal-centered excited electronic states . We as well as other research groups have established a class of such ligands in emissive transition metal complexes in the past decade, namely cyclometalated N -heterocyclic carbene (C^C*) ligands. ,− As derivatives of the more common 2-phenylpyridines (C^N), the C^C* ligands help to facilitate more energy-rich emissions due to the stronger donor effect of the carbene motif.…”

Enhancement of Blue Doping-Free and Hyperfluorescent Organic Light Emitting Diode Performance through Triplet–Triplet Annihilation in the Derivatives of Anthracene and Carbazole

“…The technology of organic light emitting diodes (OLEDs) needs to solve the issue of the stability and efficiency of devices, especially those with the blue color of emission, for the further advancement in the market of displays and lighting devices. − Nowadays, OLED displays and lighting devices waste ca. 50% of their power because of the low efficiency of the blue fluorescent emitters currently used in OLEDs. , In addition, blue pixels often account for ca. 50% of the total display structure, along with red and green pixels .…”

The Synthesis and Crystallographic Characterization of Emissive Pt(II) and Au(I) Compounds Exploiting the 2-Ethynylpyrimidine Ligand

“…This method has been previously exploited with various Pt(II) [4,5] and Au(I) [6] compounds to generate luminescent materials, which have applications in numerous devices including OLEDs [7]. Despite progress in developing OLEDs using organometallic phosphors, the development of materials with deep blue emission still receives significant attention [8][9][10][11], and thus general strategies to blue-shift emission are important. Regarding Pt(II) species, the emission of these compounds can be blue-shifted by decreasing the electron density of the alkynyl ligand.…”