Highly ordered TiO2 nanowire (TN) arrays were prepared in anodic alumina membranes (AAMs) by a sol-gel method. The TNs are single crystalline anatase phase with uniform diameters around 60 nm. At room temperature, photoluminescence (PL) measurements of the TN show visible broadband three peaks, which located at about 425, 465, and 525 nm that attributed to self-trapped excitons, F, F+ centers, respectively. A model is also presented explain PL intensity drop-down embedded AAMs: blue band...

Herein, we report a general strategy for achieving ultra-pure green emissions by suppressing the shoulder peaks in emission spectra of conventional polycyclic aromatic hydrocarbons (PAHs). Through precise synthetic fusion multi-resonance (MR) fragments with PAH, extended π-conjugation lengths, increased molecular rigidity, and reduced vibrational frequency could be simultaneously realized. The proof-of-concept emitters exhibited dominant at ca. 521 nm, photoluminescence quantum yields that...

Thermally activated delayed fluorophors (TADF) featuring through-space charge transfers (TSCT) suffer from low radiative decay rates (kr s), especially for blue emitters. Here, a xanthene bridge is adopted to construct space-confined face-to-face donor-acceptor alignment and minimize their distances down 2.7-2.8 Å, even shorter than the interlayer distance of graphite thus strengthening electronic interactions. The resulting TSCT-TADF emitters exhibit peaks around ≈460 nm, photoluminescence...

The pursuit of ideal short-delayed thermally activated delayed fluorescence (TADF) emitters is hampered by the mutual exclusion a small singlet-triplet energy gap (ΔEST) and large oscillator strength (f). Here, attaching an multiresonance-acceptor onto sterically-uncrowded donor, we report TADF bearing hybrid electronic excitations with main donor-to-acceptor long-range (LR) auxiliary bridge-phenyl short-range (SR) charge-transfer characters, balancing ΔEST f. Moreover, incorporation dual...

Polycyclo-heteraborin multi-resonance (MR) emitters are promising for high color-purity organic light-emitting diodes (OLEDs). Here, unlike the most common heteroatom ternary-doped (X/B/N) frameworks, a binary-doped (B/N) skeleton is reported with large energy band wide-range color tunability. Based on this parent-segment, "one-pot" catalyst-free borylation method developed which generates deep blue to pure green MR from readily available starting materials, peaks at 426-532 nm and...

The pursuit of ideal narrowband yellow multiple resonance (MR) emitters is hampered by the mutual constraints effective spectral redshift and maintaining a small full width at half maximum (FWHM) value. Here, novel fusion molecular design strategy reported to break this trade-off. Compared with selected parent core, specific MR effects in target molecules can simultaneously extend π-conjugation length, increase rigidity structure, reduce vibrational frequency. Proof-of-the-concept BN-DICz...

Chiral B/N embedded multi-resonance (MR) emitters open a new paradigm of circularly polarized (CP) organic light-emitting diodes (OLEDs) owing to their unique narrowband spectra. However, pure-red CP-MR and devices remain exclusive in literature. Herein, by introducing B-N covalent bond lower the electron-withdrawing ability para-positioned B-π-B motif, first pair double hetero-[n]helicenes (n = 6 7) emitter peaking 617 nm with small full-width at half-maximum 38 high photoluminescence...

Stable deep blue multiresonance emitters with small full width at half maximum (FWHM) are attractive for wide color-gamut organic light-emitting diodes (OLEDs). However, the steric repulsion from spatially close hydrogens would twist skeletons, causing spectral broadening and molecular instability issues. Here, we strategically introduce a mesitylboron locking unit into carbazole-embedded model emitter, alleviating hydrogen repulsions also strengthening para-positioned weak carbon-nitrogen...

Abstract Embedding nitrogen/carbonyl (N/C═O) units into rigid heterocyclic aromatic hydrocarbons creates novel multi‐resonant thermally activated delayed fluorescence (MR‐TADF) molecules. Nevertheless, the intrinsic short‐range charge transfer (SRCT) characteristics of N/C═O derivatives, as exemplified by quinolino[3,2,1‐ de ]acridine‐5,9‐dione (QAO), result in broad spectral bandwidths, posing challenging for achieving deep blue emission. Herein, a pentagonal cyclization and isomeric...

Abstract Enantiopure molecules based on macrocyclic architecture are unique for applications in enantioselective host‐guest recognition, chiral sensing and asymmetric catalysis. Taking advantage of the transfer from intrinsically planar chirality pillar[5]arenes, we herein present an efficient straightforward approach to achieve early examples highly luminescent systems ( P5NN P5BN ). The optical resolution their enantiomers has been carried out via preparative HPLC, which was ascribed...

New symmetric and unsymmetric B,N,B-doped benzo[4]helicenes 3-6 a/b have been achieved in good yields, using a three-step process, starting from N(tolyl)3 highly divergent manner (7 examples). A borinic acid functionalized 1,4-B,N-anthracene 1 was found to display unprecedented reactivity, acting as convenient effective precursor for selective formation of bromo-substituted B,N,B-benzo[4]helicenes 2 a/2 b via intramolecular borylation sequential B-Mes bond cleavage the presence BBr3 ....

Abstract Three isomeric boron‐containing thermally activated delayed fluorescent (TADF) emitters, namely m ‐AC‐DBNA, p and ′‐AC‐DBNA, are constructed by incorporating an electron‐donor acridine (AC) moiety into meta ‐, para or ′‐positions of electron‐accepting boron‐embedded rigid framework. The substitutional positions found to dramatically affect thermal, photophysical, electroluminescent (EL) properties. experimental results show that the ‐substituted compound ( ‐AC‐DBNA) exhibits higher...

High-efficiency and stable deep-blue bottom-emitting organic light-emitting diodes with Commission Internationale de l'Eclairage

Nitrogen-containing polycyclic heteroaromatics have exhibited fascinating multi-resonance (MR) characteristics for efficient narrowband emission, but strategies to bathochromic shift their emissions while maintaining the narrow bandwidths remain exclusive. Here, homogeneous hexatomic rings are introduced into nitrogen-embedded MR skeletons prolong π-conjugation length low-energy electronic transitions retaining non-bonding character of remaining parts. The proof-of-the-concept emitters...

Despite the remarkable multiple resonance (MR) optoelectronic properties of organic nanographenes with boron and nitrogen atoms disposed para to each other, synthetic procedures are sophisticated low yields molecular skeletons limited. Here, a new paradigm easy-to-access MR emitter is constructed by simplifying multiborylation through amine-directed formation B-N bonds while introducing an additional para-positioned atom trigger effect. The proof-of-concept molecules exhibit narrowband...

Thermally activated delayed fluorophores (TADF) with donor-acceptor (D-A) structures always face strong conjugation between donor and acceptor segments, rendering delocalized new molecular orbitals that go against blue emission. Developing TADF emitters colors, high efficiencies, long lifetimes simultaneously is therefore challenging. Here, a D-void-A structure D A moieties connected at the void-position where frontier orbital from cannot be distributed, resulting in nonoverlap of proposed....

Multi-resonant thermally activated delayed fluorescence (MR-TADF) materials have attracted considerable attention recently. The molecular design frequently incorporates cycloboration. However, to the best of our knowledge MR-TADF compounds containing nitrogen chelated boron are still unknown. Reported herein is a new class tetracoordinate boron-containing emitters bearing C^N^C- and N^N^N-chelating ligands. We demonstrate that replacement B-C covalent bond in C^N^C-chelating ligand by B-N...

Fusing condensed aromatics into multi-resonance (MR) frameworks has been an exquisite strategy to modulate the optoelectronic properties, which, however, always sacrifices small full width at half maxima (FWHM). Herein, we strategically embed B-N/B-O contained heterocycles as fusion locker classical MR prototypes, which could enlarge π-extension and alleviate steric repulsion for enhanced planar skeleton suppress high-frequency stretching/ scissoring vibrations ultra-narrowband emissions....

Compared with the classical boron/nitrogen (B/N) doped ones, multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters embedded B-N covalent bond behave a significantly blue-shifted narrowband TADF, and thus show greater potential in ultrapure blue organic light-emitting diodes (OLEDs). As proof of concept, herein peripheral substitution engineering is demonstrated based on such B‒N parent core. The simple approach found to ensure easy synthesis via one-pot lithium-free...

Expanded heterohelicene composing of alternating linearly and angularly fused multi‐resonance (MR) skeleton has garnered wide interest for their promising narrowband emission. Herein, a pair sym‐ asym‐expanded isomers are firstly developed by merging boron/oxygen (B/O)‐embedded MR triangulene indolo[3,2,1‐jk]carbazole units via one‐shot synthesis. Owing to the fully resonating extended helical skeleton, target heterohelicenes exhibit significantly narrowed spectra bandwidth while emission...

S-doped ZnO nanowires with an average diameter of 80 nm and length up to several tens micrometers were produced through a simple physical evaporation approach. The had single-crystal hexagonal structure grew along the [102] direction. Photoluminescence (PL) measurements showed that doping sulfur shifted PL spectrum peak towards short wavelengths, quantity was found responsible for different characteristics.

α-Al2O3 nanowires and nanobelts have been successfully synthesized from Al pieces SiO2 nanoparticles at 1200 °C 1150 °C, respectively, in a flowing Ar atmosphere. The are uniform with diameters of 20−70 nm lengths 15−25 μm, the several to tens micrometers long, width 0.1−1 μm thickness 10−50 nm. growth is controlled by vapor−liquid−solid (VLS) mechanism, while may be due vapor−solid (VS) process. Infrared spectra these nanostructures different that bulk α-Al2O3. Photoluminescence (PL)...

Ultralong afterglow emissions due to room-temperature phosphorescence (RTP) are of paramount importance in the advancement smart sensors, bioimaging and light-emitting devices. We herein present an efficient approach achieve rarely accessible heavy atom-free organoboranes via photochemical switching sterically tunable fluorescent Lewis pairs (LPs). LPs widely applied well-known for their outstanding performance catalysis supramolecular soft materials but have not thus far been exploited...