Non-doped OLEDs based on tetraphenylethylene phenanthroimidazoles with negligible efficiency roll-off: effects of end group regulated stimulus responsive AIE luminogens

Abstract

The positional isomers of phenanthroimidazoles, TPE-NPPB and TPE-APPB have been designed to understand the positional effect of triphenylamine (TPA) and tetraphenylethylene (TPE) units on aggregation induced emission and mechanochromism. Phenanthroimidazoles,...

Approaches for Fabricating Tri‐ and Tetraphenylethene‐Based Blue Organic Light‐Emitting Diodes Using Donor–Acceptor and Non‐Donor–Acceptor Molecular Architectures

“…Reversible mechanochromism was observed between the green and blue color in compounds 193 and 194 . [ 101 ] The isomers exhibited the morphological change with the color variation in the amorphous and crystalline state. The imidazole‐based derivatives afford the hydrogen bonding and close packing in the solid state, resulting in AIEE.…”

Doped and non-doped blue organic light-emitting diodes based on AIEgens with high exciton utilization efficiency and external quantum efficiency

“…The increase of k r and decrease of k nr of CNSPI-DVP and NSPI-DVP is in line with the aim of our design strategy. The decrease of non-radiative rate (k nr ) of CNSPI-DVP and NSPI-DVP in solution relative to that of film may due to restriction of intermolecular motion (RIM) which is the cause of AIE behaviour of CNSPI-DVP and NSPI-DVP [33,34]. The aggregates at higher % H 2 O addition limits the rotation of aryl moiety and intensified the emission with bathochromic shift (Figure 7).…”

“…The excited state properties of NSPI-DVP and CNSPI-DVP were analysed by solvent effect (Figures S2: TablesS3&S4). The NSPI-DVP and CNSPI-DVP show red shifted emission with increasing solvent polarity due to intramolecular charge transfer interaction of solvent with solute and defined by Lippert-Mataga plot [hc(ῦ abs -ῦ flu ) = hc(-) + 2 ℎ ῦ abs ℎ ῦ (µ e -µ g ) 2 / ][34, 35]. The variation of Stokes shift of NSPI-DVP and CNSPI-DVP with3 o solvent polarity exhibit double linear relationship confirmed the HLCT behaviour (Figure 3).…”

Mechanoluminescence and Aggregation-Induced Emission in Bipolar Phenanthroimidazoles: Role of Positional Isomerization-Induced Switching Effect

“…The phenanthroimidazole derivatives with two donors, triphenylamine (D) and tetraphenylethenylphenyl (D), which have been interchanged at the C2/N1 positions, exhibit a distinctive conjugation effect which is crucial for the MFC behavior . Compared with the C2- and N1-substituted phenanthrimidazoles, C6- and C9-substituted phenanthrimidazoles decreased the molecular conjugation . However, the positional isomers of phenanthrimidazole having a donor and an acceptor were interchanged at the C2- and N1-positions, exhibiting different dipole moments and showing excellent ML behavior.…”

“…28 Compared with the C2-and N1-substituted phenanthrimidazoles, C6-and C9substituted phenanthrimidazoles decreased the molecular conjugation. 29 However, the positional isomers of phenanthrimidazole having a donor and an acceptor were interchanged at the C2-and N1-positions, exhibiting different dipole moments and showing excellent ML behavior.…”