In Situ Solid-State Generation of (BN)2 -Pyrenes and Electroluminescent Devices.

New BN-heterocyclic compounds have been found to undergo double arene photoelimination, forming rare yellow fluorescent BN-pyrenes that contain two BN units. Most significant is the discovery that the double arene elimination can also be driven by excitons generated electrically within electroluminescent (EL) devices, enabling the in situ solid-state conversion of BN-heterocycles to BN-pyrenes and the use of BN-pyrenes as emitters for EL devices. The in situ exciton-driven elimination (EDE) phenomenon has also been observed for other BN-heterocycles.

Exciton-stimulated molecular transformation in organic light-emitting diodes.

An exciton-stimulated molecular transformation in an organic light-emitting diode (OLED) on a time scale of a few seconds under electrical bias is shown to reach nearly 100% under standard operating conditions, leading to color switching. It is reversible in both a thin film and an OLED when sufficient thermal energy is supplied. Such an exciton-stimulated molecular transformation suggests a new process which may be exploited for applications such as electrochromic and memory devices.

Highly efficient blue phosphorescence from triarylboron-functionalized platinum(II) complexes of N-heterocyclic carbenes.

The first examples of BMes(2)-functionalized NHC chelate ligands have been achieved. Their Pt(II) acetylacetonate complexes have been synthesized and fully characterized. These NHC-chelate Pt(II) compounds display highly efficient blue or blue-green phosphorescence in solution (Φ = 0.

Bluish-green BMes2-functionalized Pt(II) complexes for high efficiency PhOLEDs: impact of the BMes2 location on emission color.

New phosphorescent Pt(II) compounds based on dimesitylboron (BMes(2))-functionalized 2-phenylpyridyl (ppy) N,C-chelate ligands and an acetylacetonato ancillary ligand have been achieved. We have found that BMes(2) substitution at the 4'-position of the phenyl ring can blue-shift the phosphorescent emission energy of the Pt(II) compound by approximately 50 nm, compared to the 5'-BMes(2) substituted analogue, without substantial loss of luminescent quantum efficiencies. The emission color of the 4'-BMes(2) substituted Pt(II) compound, Pt(Bppy)(acac) (1) can be further tuned by the introduction of a substituent group at the 3'-position of the phenyl ring.

Molecular beam epitaxial growth and characterization of non-tapered InN nanowires on Si(111).

We have performed a detailed investigation of the molecular beam epitaxial growth and characterization of InN nanowires spontaneously formed on Si(111) substrates under nitrogen rich conditions. By employing an in situ deposited thin (approximately 0.5 nm) In seeding layer prior to growth initiation, we have achieved, for the first time, non-tapered epitaxial InN nanowires, which exhibit record narrow spectral linewidths of 14 and 40 meV at 5 K and 300 K, respectively.