Effect of electric fields on photoluminescence of 4-(dicyanomethylene)-2-methyl- 6-(p-dimethylaminostyryl)-4H-pyran

Highly Efficient, Simplified, Solution‐Processed Thermally Activated Delayed‐Fluorescence Organic Light‐Emitting Diodes

“…The aggregated and non‐uniformly dispersed dopants in the CBP:4CzIPN layer cast from toluene solution also showed much faster PL decay under wavelength λ = 350 nm illumination from a Xe lamp than did the CBP:4CzIPN layer in the THF solution (Figure d and Figure S3, Supporting Information). Solution processing with THF, which provides much improved solubility of 4CzIPN, not only improved the layer uniformity and the PL intensity but also improved the photostability of the EML by minimizing the aggregation and maximizing the dopant uniformity in the host matrix …”

“…As the dipole moment of solvents increased from 0.31 D (toluene) to 1.75 D (THF), average PL intensity of films cast from the THF solution was doubled compared with that from the toluene solution, and the standard deviation of PL intensity of films cast from the THF solution is 0.98% which is much smaller than that from the toluene solution (9.52%) ( Figure c and Figure S2, Supporting Information). This result implies that as the dipole moment of the solvent increases, dissolution of 4CzIPN dopants with high dipole moment (≈3.95 D) was improved in the CBP matrix, reduced the aggregation of 4CzIPN, and increased the PL intensity of the resulting uniform CBP:4CzIPN layer . The aggregated and non‐uniformly dispersed dopants in the CBP:4CzIPN layer cast from toluene solution also showed much faster PL decay under wavelength λ = 350 nm illumination from a Xe lamp than did the CBP:4CzIPN layer in the THF solution (Figure d and Figure S3, Supporting Information).…”

Quadrupolar Chromophores for Voltage Sensing and White‐Light Generation

“…[1][2][3] On the other hand, the luminescence of dipolar chromophores is too weakly affected by applied fields to build useful color-tunable LEDs based on dipolar dyes. [4] Quadrupolar chromophores, characterized by a D-p-A-p-D or A-p-D-p-A motif (A and D are electron-acceptor and electron-donor groups and p represents a p-conjugated bridge), are an interesting class of molecules for their large two-photon absorption cross sections, but so far they have not been thoroughly considered for voltage-sensing or LED applications. Here we extend the essential-state model, recently proposed to describe optical spectra of quadrupolar chromophores, to account for the effects of an applied static electric field.…”