Ambipolar Transporting 1,2‐Benzanthracene Derivative with Efficient Green Excimer Emission for Single‐Layer Organic Light‐Emitting Diodes

Abstract

Single‐layer organic light‐emitting diodes (OLEDs) are highly desired due to their potential advantages such as simplifying the fabrication process and lowering the cost. However, high‐performance single‐layer OLEDs are rare in the literature as they require bipolar transporting materials with balanced electron and hole mobilities, high fluorescent quantum yields, and good energy levels matching both electrodes. In this work, a bipolar transporting benzanthracene derivative, namely 7,12‐bis‐[4‐(2,2‐diphenylvinyl)‐phenyl] benzanthracene (BDPBan), is designed and synthesized without any structural motifs for hole and electron transport. As electrons and holes can perform intermolecular hopping to similar spatial extents between the adjacent benzanthracene moieties, well‐balanced hole and electron mobilities higher than 10−3 cm2/Vs are achieved. Though the strong intermolecular interactions facilitate the formation of excimers in concentrated solutions and thin films of BDPBan, efficient undoped single‐layer OLEDs are fabricated with strong green emission from the excimers. A device with 90 nm BDPBan as the emitting layer shows a peak current efficiency of 11.4 cd/A: beyond the conventional upper limit calculated based on the photoluminescence quantum yield.

Excimer Diffusivity in 9,10-Bis(phenylethynyl)anthracene Assemblies on Anodic Aluminum Oxide Membranes

“…The strong electronic coupling between the molecules in self-assembled 9,10-bis­(phenylethynyl)­anthracene (BPEA) molecules covalently bound to AAO membranes induces excimer formation, which has been observed for BPEA molecular dimers . In light harvesting applications, the excimer is often viewed as an undesirable lower energy trap state. , Despite their lower energy compared to the first singlet excited state, pyrene excimers have a high fluorescence quantum yield, making them good blue light emitters; benzanthracene excimers emit green light, useful for organic light-emitting diodes (OLEDs), and cyanovinylene excimers can probe caspase for disease diagnostics . Additionally, the lifetime of excimer states typically exceeds that of the singlet excited state of one of the constituent chromophores, which enhances their ability to undergo further transformation or to be harvested prior to decay.…”

A Novel Spiro[acridine‐9,9′‐fluorene] Derivatives Containing Phenanthroimidazole Moiety for Deep‐Blue OLED Application

“…[10b] Notably, the efficiency rolloff of SAF-BPI-based device is relatively small with CE 3.35, 2.85 cd A À1 at 100, 1000 cd m À2 ,r espectively;e ven at the maximum brightness of 2122 cd m À2 ,t he CE still remains 2.28 cd A À1 .T he low efficiency roll-off might result from the bipolar properties of SAF-BPI and the consequentb alance of hole and electron recombination in the emissive layer. [23] Deep-blue emission is observed with maximum emission peak at 448 nm, Commission International deL'Eclairage (CIE) coordinate of (0.15, 0.10) andanarrow full width at half maximum (FWHM) of 62 nm (Figure 6c). The CIE coordinate is very close to the standard blue coordinate of National Te levision StandardC ommittee (NTSC) (0.14, 0.08).…”

Nine-ring angular fused biscarbazoloanthracene displaying a solid state based excimer emission suitable for OLED application

“…48 Despite the fact that the energies of the orbitals of 3 are well fitting versus the respective energy levels of ETL and HTL (Fig. 11) some of the OLED parameters might be suppressed due to unbalanced hole and electron recombination 49 or relatively moderate mobility of the thin layer (vide supra). Nonetheless we assume that the assembly of the energy levels should diminish the turn on voltage.…”