The development of white-light-emitting
polymers has been actively
pursued because of the importance of such polymers in various applications,
such as lighting sources and displays. To generate white-light, numerous
research efforts have focused on synthesizing multifluorophore-based
random copolymers to effectively cover the entire visible region.
However, due to their intrinsic synthetic and structural features,
this strategy has limitations in securing color reproducibility and
stability. Herein, we report the development of single-fluorophore-based
white-light-emitting homopolymers with excellent color reproducibility.
A powerful direct C–H amidation polymerization (DCAP) strategy
enabled the synthesis of defect-free polysulfonamides that emit white-light
via excited-state intramolecular proton-transfer (ESIPT). To gain
structural insights for designing such polymers, we conducted detailed
model studies by varying the electronic nature of substituents that
allow facile tuning of the emission colors. Further analysis revealed
precise control of the thermodynamics of the ESIPT process by fine-tuning
the strength of the intramolecular hydrogen bond. By applying this
design principle to polymerization, we successfully produced a series
of well-defined polysulfonamides with single-fluorophore emitting
white-light. The resulting polymers emitted consistent fluorescence,
regardless of their molecular weights or phases (i.e., solution, powder,
or thin film), guaranteeing excellent color reproducibility. With
these advantages in hand, we also demonstrated practical use of our
DCAP system by fabricating a white-light-emitting coated LED.
Triazoliptycene fluorophores have been designed and synthesized, in which a three-dimensional propeller-like iptycene motif is employed to suppress intermolecular π-π stacking in the solid state. Key to the success of this modular synthesis is a stereoelectronic bias imposed by the iptycene scaffold, which assists the desired regioselectivity in the C-N cross-coupling step as the last-stage structure diversification from a common precursor.
With small molecules, it is not easy to create large void spaces. Flat aromatics stack tightly, while flexible chains fold to fill the cavities. As an intuitive design to make...
Discovery of a new chemical moiety is the foundation to build new functional materials. For charge-transfer-type thermally activated delayed fluorescence (TADF) emitters, donor, acceptor, and π-spacer are the three key structural components. We invented a "click-to-twist" strategy to prepare a triazole-based acceptor unit that allows for a systematic modulation of the electronic and steric properties to control the excited-state photophysics. Taking the modular approach, six different emitters were prepared by varying the donor strength and π-spacer sterics for mix-and-match. These materials display deep blue to sky blue emissions in solutions, as well as apparent TADF characteristics in doped films. Organic light emitting diodes fabricated with these new TADF materials exhibit high external quantum efficiencies of up to 20.7% and maximum luminance of 6823 cd m −2 . Building upon an intuitive and operationally straightforward method to build sterically congested molecules, this work showcases a new strategy to diversify TADF emitters by a mechanism-based design and modular synthesis.
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