Although bowl‐shaped N‐pyrrolic polycyclic aromatic hydrocarbons (PAHs) can achieve excellent electron‐donating ability, their application for optoelectronics is hampered by typically low photoluminescence quantum yields (PLQYs). To address this issue, we report the synthesis and characterization of a series of curved and fully conjugated nitrogen‐doped PAHs. Through structural modifications to the electron‐accepting moiety, we are able to switch the mechanism of luminescence between thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP), and to tune the overall PLQY in the range from 9 % to 86 %. As a proof of concept, we constructed solid‐state organic light‐emitting diode (OLED) devices, which has not been explored to date in the context of concave N‐doped systems being TADF/RTP emitters. The best‐performing dye, possessing a peripheral trifluoromethyl group adjacent to the phenazine acceptor, exhibits yellow to orange emission with a maximum external quantum efficiency (EQE) of 12 %, which is the highest EQE in a curved D‐A embedded N‐PAH to date.

Exploring the design principle for switching thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) is a fundamentally imporant research in developing triplet-mediated photofunctional organic materials. Herein systematic studies...

Hyperfluorescence (HF), a relatively new phenomenon utilizeing excitones transfer between two luminophores, requires careful pairwise tuning of molecular energy levels and is proposed to be the crucial step towards the...

A new family of thermally activated delayed fluorescence (TADF) emitters based on a twisted donoracceptor (DÀ A) dyad scaffold comprising of dihydrophenazasiline (D) and pyrido[2,3-b]pyrazine (A) has been developed, and their properties have been investigated. Time-resolved spectroscopic analysis in matrices revealed the detailed photophysical properties of the DÀ A compounds. These DÀ A compounds serve as the emitter for organic light-emitting diodes (OLEDs), showing a moderate external quantum efficiency (EQE) up to 9% in CBP matrix. Furthermore, theoretical calculations uncovered the excited states nature of the developed TADF emitters.

A novel silsesquioxane material was synthetized and used as a stabilizing agent for silver nanoparticles. This hybrid material was characterized by FTIR, 29Si CP‐MAS NMR, 13C DEPT 135° NMR and TGA techniques and the silver nanoparticles were characterized from DLS, UV‐Vis spectroscopy, zeta‐potential, TEM and SAXS results. The silver nanoparticles obtained were spherical in shape with a diameter of 3.74 nm. The nanomaterial was successfully applied in the modification of a glassy carbon electrode and a pronounced current response was obtained in the determination of the biomarker 4‐nitrophenol. Quantum chemical calculations, using density functional theory, were also performed in order to evaluate the redox properties of the analyte. Two different linear ranges were obtained applying optimal square wave voltammetry conditions. The reduction peak currents obtained were linear for 4‐NP concentrations in the ranges of 0.29 to 1.50 μmol L−1 (Ed=−0.6 V and td=20 s) and 2.75 to 31.5 μmol L−1, with a theoretical (signal to noise=3) limit of detection of 0.05 μmol L−1 (td=20 s). The proposed method was successfully applied to the determination of 4‐NP in synthetic serum samples at different levels of 4‐NP with a recovery range of 94–101 %. Validation was performed using a comparative method through the capillary electrophoresis (CE) technique.