Organic ultralong room temperature phosphorescence (OURTP) materials with photophysical properties sensitive to external stimulus are highly attractive for advanced applications.H owever,m ost OURTPm olecules are in crystal and OURTP materials with good practicability and stimulusresponsive character are hard to be achieved. Here,wereport, for the first time,the highly efficient, ultralong-lived and deepblue OURTPmaterials by simply doping boron phosphor into cyanuric acid host. Host-guest OURTP composites with abundant and tunable H-bond network are highly stable in air with ultralong lifetime of 5.08 satroom temperature.They are sensitive to water,which can strength the H-bond network to significantly enhance OURTP quantum yield from 16.1 %to 37.6 %. Anti-counterfeiting paper was easily prepared for water-jet printing;t he jet-printed high-resolution OURTP patterns can be easily erased by solvent fuming for another printing/erasing cycle with high reversibility.
Achieving single-component white organic afterglow remains ag reat challenge owingt ot he difficulties in simultaneously supporting long-lived emissions from varied excited states of am olecule for complementary afterglow.Here,a ne xtraordinary tri-mode emission from the radiative decays of singlet (S 1 ), triplet (T 1 ), and stabilized triplet (T 1 * ) excited states was proposed to affordw hite afterglowt hrough modulating the singlet-triplet splitting energy (DE ST )a nd exciton trapping depth (E TD ). Low-lying T 1 *f or yellow afterglow was constructed by H-aggregation engineering with large E TD and trace isomer doping, while high-lying T 1 and S 1 for blue afterglow with thermally activated emission feature were realized by reducing DE ST through donor-acceptor molecular design. Therefore,t he single-component white afterglow with high efficiency of 14.1 %a nd al ifetime of 0.61 sw as achieved by rationally regulating the afterglow intensity ratios of complementary emissions from S
Circularly
polarized luminescence (CPL) molecules, especially those
with thermally activated delayed fluorescence (TADF) properties, have
attracted considerable attention due to their great potential for
chiroptical organic light emitting diode (OLED) devices. Here we developed
a new pair of TADF emitters with CPL based on boron complexes using
chiral donor (cD) binaphthalene, acceptor (A) biphenyl boron β-diketonate,
and donor (D) biphenylamine in a cD–A–D architecture.
With this design, both efficient intramolecular charge transfer (ICT)
and chiral ICT for high-performance CPL were established, leading
to high dissymmetry factors (|g
lum|) up
to 2.2 × 10–3 in solution and significantly
red-shifted emission around 600 nm for red TADF with a quantum yield
over 15% in doped films. More impressively, with these chiral TADF
emitters, solution-processed red circularly polarized OLEDs (CP-OLEDs)
exhibit external quantum efficiencies (EQEs) up to 2.0% and efficient
circularly polarized electroluminescence with dissymmetry factors
of 2.6 × 10–3, which are among the best performances
of the reported solution-processed orange-red and red TADF CP-OLEDs.
These results illustrate the great success of the cD–A–D
strategy in designing high-performance CPL TADF emitters with axially
chiral boron complexes, providing important clues to understand efficient
chiral transfer for large |g
lum| values
and high device performance of CP-OLEDs.
An intermolecular locking strategy was proposed to improve both the solution processibility and photoluminescence efficiency of red TADF emitters for solution-processed OLEDs with an EQE up to 8.2% and an efficiency roll-off of 9.0% at 1000 cd m−2.
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