Herein, we discuss an imidazole-based molecular framework, which can successfully transform triplet excitons present in high triplet levels into singlet states. We explain the working mechanisms of different methods for collecting triplet excitons, including hot excitons or HLCT states. After the development of an hot exciton material by Ma and Yang, many studies have demonstrated that the organic conjugated molecules having imidazole core have possibilities to show high efficiencies hot exciton pathways. Finally, we provide a detailed investigation of recently published hot exciton luminogens based on imidazole molecular frameworks. This review provides an overview of the molecular structures, frontier molecular orbital information, and glass transition temperature of developed luminogens as well as the efficiency of organic light-emitting diodes (OLED) devices.
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http://dx.doi.org/10.1039/d3sm01005h | DOI Listing |
ACS Nano
January 2025
Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos 13566-590, Brazil.
Monolayers of transition-metal dichalcogenides, such as MoS, have attracted significant attention for their exceptional electronic and optical properties, positioning them as ideal candidates for advanced optoelectronic applications. Despite their strong excitonic effects, the atomic-scale thickness of these materials limits their light absorption efficiency, necessitating innovative strategies to enhance light-matter interactions. Plasmonic nanostructures offer a promising solution to overcome those challenges by amplifying the electromagnetic field and also introducing other mechanisms, such as hot electron injection.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, 999077, China.
As the investigation of high efficiency thermally activated delayed fluorescence (TADF) materials become more mature, regulating the emission properties for single organic luminescence molecules has gained increasing interest recently. Herein, the donor-acceptor compounds F-AQ comprised of fluorene and anthraquinone is reported, and it exhibits a polymorphism with muti-color emission and TADF from high-level intersystem crossing (hRISC). The photodynamics and excited-state transient species were studied by femtosecond transient absorption (fs-TA) spectroscopy.
View Article and Find Full Text PDFSmall
January 2025
Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
The ligands in metal-organic framework (MOF) play as light absorption center and transfer photogenerated electrons to metal node through ligand-to-metal charge transfer (LMCT) during photocatalysis, and energy utilization efficiency is strongly restricted by the light inertness of ligands. Herein, a ligand updating strategy is proposed by inserting energy centers to MOFs to activate the inherent ligands, realizing boosting hot electron generation and photocatalytic activities via the cascaded proceeding of energy transfer and charge transfer. By taking PCN-777 (a zeotype mesoporous Zr-containing MOF) as an example, this study shows that the embedded energy center of 1-pyrenecarboxylic acid (PCA) can activate the inherent ligand of PCN-777 through triplet-triplet energy transfer, where triplet excitons would dissociate into photocarriers migrating to the Zr metal cluster via LMCT process.
View Article and Find Full Text PDFSci Adv
January 2025
Department of Physics, Pusan National University, Busan 46241, Republic of Korea.
Metal electrode deposition is universally adopted in the community for optoelectronic device fabrication, inducing hybridization at electrode interfaces, and allows efficient extraction or injection of photocarriers. However, hybridization-induced midgap states increase photocarrier recombination pathways, creating a paradoxical trade-off. Here, we discovered that efficient photocarrier extraction and a long photocarrier lifetime can be achieved simultaneously in MoS/van der Waals Au contact, minimizing photocarrier loss at the interface.
View Article and Find Full Text PDFNano Lett
December 2024
Graduate School of Science, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo 669-1330, Japan.
In colloidal quantum dots (QDs), excitons are confined within nanoscale dimensions, and the relaxation of hot electrons occurs through Auger cooling. The behavior of hot electrons is evident under ambient pressure. Nanocrystal characteristics, including their size, are key to determining hot electron behavior because they serve as the stage.
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