Tailoring the Size and Shape of ZnO Nanoparticles for Enhanced Performance of OLED Device

We synthesized zinc oxide nanoparticles (ZnO NPs) by meticulously controlling both temperature and reaction times, allowing us to fine-tune their crystalline properties, morphology, and particle dimensions. This analysis confirmed the existence of a mixture of rod and sphere shapes (ZnO-I), including rod-shaped NPs with an average size of 14.8 nm × 5.2 nm and spherical NPs with an average diameter of 5.27 nm. We subsequently incorporated these synthesized ZnO NPs into organic light-emitting diode (OLED) devices for red, green, and blue colors, utilizing them as the electron injection layer through a solution-based process. The green OLED device using ZnO-I exhibited a promising current efficiency of 4.02 cd/A and an external quantum efficiency of 1.47%.

A Novel Donor-Acceptor Thiophene-Containing Oligomer Comprising Dibenzothiophene-S,S-dioxide Units for Solution-Processable Organic Field Effect Transistor

A π-conjugated thiophene-containing oligomer with a D-A-D-A-D (D: donor, A: acceptor) architecture, namely, 2,6-bis{[4-(7-n-hexylthiophen-2-yl)thiophen-2-yl]-(dibenzothiophene-5,5-dioxide-3,3΄-diyl)}-bis((2-ethyl-hexyl)oxy)benzo[1,2-b:4,5-b’]dithiophen (BDT(DBTOTTH)₂), was synthesized by Stille coupling reactions. There are obvious shifts in the Ultraviolet-visible (UV-vis) and photoluminescence (PL) spectra of the thin film relative to its solution, indicating the existence of the π-π stacking in the solid state of the oligomer BDT(DBTOTTH)₂. The optical band gap of the oligomer determined from its absorption onset in UV-Vis spectra is 2.25 eV. It agrees with the value of 2.29 eV determined from the cyclic voltammetry (CV) measurement. Its highest occupied and lowest unoccupied molecular orbital (HOMO/LUMO) energy levels, which were calculated from its onset of oxidation and reduction waves in CV curve, are −5.51 and −3.22 eV, respectively. The oligomer is a P-type semiconductor material with a good thermal stability and solubility, which can be used to fabricate organic field effect transistors (OFETs) by the spin coating technique. The OFET with n-octadecanylltrichlorosilane (OTS)-modified SiO₂ dielectric layer exhibited a mobility of 1.6 × 10⁻³ cm²/Vs.

Rh(III)-Catalyzed Oxidative C-2 Coupling of N-Pyridinylindoles with Benzo[b]thiophene 1,1-Dioxides via C-H Bond Activation

An efficient Rh(III)-catalyzed cross-dehydrogenative coupling of N-pyridinylindoles with benzo[b]thiophene 1,1-dioxides has been developed through directing-group-assisted C-H activation. This transformation constructs a new C-C bond from two inert C-H bonds in a one-pot reaction. The present reaction is compatible with various functional groups with respect to indoles and benzothiophene[b] 1,1-dioxides. Furthermore, the emission properties of synthesized compounds have been explored.

Ambient-Processed, Additive-Assisted CsPbBr3 Perovskite Light-Emitting Diodes with Colloidal NiOx Nanoparticles for Efficient Hole Transporting

In this study, the electrically driven perovskite light-emitting diodes (PeLEDs) were investigated by hybridizing the organic polyethylene oxide, 1,3,5-tris (N-phenylbenzimiazole-2-yl) benzene (TPBi), and bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) with CsPbBr3 in the emission layer and adopting the colloidal NiOx nanoparticle (NP) hole transport layer. The synthesized NiOx NPs, having an average size of ~5 nm, can be spin-coated to become a smooth and close-packed film on the indium–tin–oxide anode. The NiOx NP layer possesses an overall transmittance of ~80% at 520 nm, which is about the peak position of electroluminescence (EL) spectra of CsPbBr3 emission layer. The coating procedures of NiOx NP and CsPbBr3 layers were carried out in ambient air. The novel PeLED turned on at 2.4 V and emitted bright EL of 4456 cd/m2 at 7 V, indicating the remarkable nonradiative-related defect elimination by organic additive addition and significant charge balance achieved by the NiOx NP layer.

CsPbBr3 Perovskite Powder, a Robust and Mass-Producible Single-Source Precursor: Synthesis, Characterization, and Optoelectronic Applications

A facile synthesis method is proposed for the mass production of high-quality CsPbBr₃ perovskite powder. It is shown that the proposed synthesis protocol is capable of producing polycrystalline CsPbBr₃ powder in quantities greater than 10 g. The derived thin films by thermal evaporation and spin-coating are of compact morphologies (root-mean-square roughness < 4 nm) without voids and pinholes. Moreover, the thin films show obvious photoluminescence (PL) with a narrow (bandwidth < 19 nm) peak centered at ∼520 nm, which is blue-shifted compared with the PL emission of the powder at 542 nm. The powder and the spin-coated film exhibit superior PL stability under long-term ambient conditions and in thermal cycling experiments performed at temperatures up to ∼120 °C. Accordingly, optoelectronic applications including the fabrication and characteristics of the electroluminescence device, the organic-inorganic powder doped with methylammonium and formamidinium ions, and fluorescent greenish-blue quantum dots are also demonstrated. On the basis of these demonstrations, the synthesized CsPbBr₃ perovskite powder can be expected to empower the advances in perovskite-related optoelectronics in the future.

Palladium-Catalyzed Intramolecular Oxidative Arylations for the Synthesis of Fused Biaryl Sulfones

This study unveils palladium-catalyzed intramolecular oxidative cyclizations in biaryl and heterobiaryl sulfones providing direct access to fused biaryl sulfones (dibenzothiophene-5,5-dioxides). Variously substituted dibenzothiophene-5,5-dioxides could be readily prepared in good to excellent yields under optimized conditions. In addition, bromination afforded dibromo derivative of dibenzothiophene-5,5-dioxides, providing platform for late-stage diversification. The translational applications of this current protocol have successfully been demonstrated in the synthesis of 2,8-diamino derivative of dibenzothiophene-5,5-dioxides, a α₇-nicotinic acetylcholine receptor agonist analogue, and novel single fluorene-tethered dibenzothiophene-5,5-dioxide, an organic emitter.