The discovery of high-performance functional materials is crucial for overcoming technical issues in modern industries. Extensive efforts have been devoted toward accelerating and facilitating this process, not only experimentally but also from the viewpoint of materials design. Recently, machine learning has attracted considerable attention, as it can provide rational guidelines for efficient material exploration without time-consuming iterations or prior human knowledge. In this regard, here we develop an inverse design model based on a deep encoder-decoder architecture for targeted molecular design. Inspired by neural machine language translation, the deep neural network encoder extracts hidden features between molecular structures and their material properties, while the recurrent neural network decoder reconstructs the extracted features into new molecular structures having the target properties. In material design tasks, the proposed fully data-driven methodology successfully learned design rules from the given databases and generated promising light-absorbing molecules and host materials for a phosphorescent organic light-emitting diode by creating new ligands and combinatorial rules.
We report a new formulation
for Golden Rule-based predictions of
photoluminescence quantum yields (PLQY) of phosphorescent emitters
containing a heavy element, and its implementation compatible with
first-principles computation frameworks. The main components of PLQY
(i.e., phosphorescent rate and intersystem crossing rate from the
lowest triplet state to the ground singlet state) are obtained through
correlation functions in time domain, and the relativistic effects
are also considered using the relativistic effective core potentials.
The spin–orbit coupling is treated in a perturbative manner
to generate spin–orbit-corrected, two-component T1 substates within single-excitation theory, where the electronic
transition dipole moments and the non-Born–Oppenheimer coupling
matrix elements to the S0 state are computed. We applied
this new approach to the photophysical properties of 34 Pt(II) complexes
designed for the organic light-emitting diode (OLED) applications
and observed a good agreement between predictions and experiments
over diverse scaffolds. For the two representative complexes, further
analysis on the nonradiative characteristics was performed based on
the decomposition of the non-Born–Oppenheimer coupling into
contributions from the nuclear vibrations and from the excited-state
electronic structures.
Novel polymers having a hole transport ability were prepared by condensation polymerization of N,N‘-diphenyl-N,N‘-bis(4-methylphenyl)-(1,1‘-biphenyl)-4,4‘-diamine (TPD) and paraformaldehyde
(FA) or benzaldehyde (BzA). From NMR spectra, it is revealed that addition condensation reactions
occurred exclusively at the para positions of TPD. TPD−FA polymer was linked not only by a methylene
linkage but also by a methylene ether linkage, while TPD−BzA polymer was only linked by a methine
linkage. The glass transition temperatures of TPD−FA and TPD−BzA were 183 and 239 °C, respectively.
The drift mobility of TPD−BzA measured by a standard time-of-flight (TOF) method was found to be on
the order of 10-5 and 10-6 cm2/(V s). The multilayer EL devices were fabricated using TPD−FA and
TPD−BzA polymers as a hole transport layer and Alq as an electron transport emitting layer. In both
devices, the initial driving voltage is about 4 V, and the maximum luminance is above 10 000 cd/m2 at 14
V. It is expected that these polymers can be used as a hole transport material in the EL device.
SUMMARY: Triphenylamine (TPA) was reacted with carbonyl compounds such as formaldehyde, butyraldehyde, benzaldehyde, and acetone in the presence of an acid catalyst. 1 H and 13 C NMR spectra revealed that the carbonyl compounds react only at the p-position of TPA. The reactivity of formaldehyde with TPA is lower than that with phenol. If equal molar amounts of formaldehyde are reacted, however, TPA condensation proceeds to high molecular weight polymers, while phenol provides only low molecular weight compounds (up to 1 000). TPA-aldehyde polymers have glass transition temperatures in the range of 135 -176 8C. These polymers show good solubility and sufficient stability after film formation.
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