A comprehensive electron wavefunction analysis toolbox for chemists, Multiwfn

The development of high‐efficiency near‐infrared (NIR) organic emitters has been severely constrained by strong and unavoidable non‐radiative decay governed by the “energy gap law”, which leads to low emission efficiencies and limited options for molecular design. Herein, comparative studies are performed on six‐ and five‐membered π‐bridge and a novel benzo[b]thiophene‐based donor is designed through elaborate molecular engineering, which outperforms widely‐used triphenylamine derivatives in constructing NIR thermally activated delayed fluorescence emitters. The benzo[b]thiophene donor/π‐bridge endows the newly synthesized molecule tBTAP with multiple advantages, including longer emission wavelength and enhanced oscillator strength compared with thiophene‐free triphenylamine donor, and suppressed high‐frequency vibrations compared with thiophene‐inserted donor. Consequently, tBTAP doped and nondoped films display pure NIR emission at peak wavelengths of 795 nm and 854 nm with state‐of‐the‐art photoluminescence quantum yields of 17.9 ± 0.3% and 4.6 ± 0.4%. The corresponding NIR OLEDs demonstrate record‐high maximum external quantum efficiencies of 3.64% (796 nm) and 1.20% (867 nm). Most importantly, nondoped device exhibits record‐long operational lifetime (LT97) of over 2150 h at 10 mA cm−2 for NIR OLEDs. This study signifies an advance in molecular engineering by designing alternative donor/π‐bridge structure, breaking through the bottleneck in developing high‐performance NIR organic emitters and devices toward practical applications.

Molecular Engineering of Donor/π‐Bridge Enables High‐Efficiency and Long‐Lifetime Near‐Infrared TADF‐OLEDs

Dai,

Xu,

Lei

et al. 2024

Formulating the Relationship Between Intermolecular Interactions and Photodynamic Effects Based on the Optical Regularity Exhibited by Rare Earth‐BODIPY Crystalline Frameworks System

Pan,

Jiang,

Gong

et al. 2024

This research commenced with an exploration of how metal nodes in metal‐organic frameworks (MOFs) influence photodynamic therapy (PDT) outcomes. Ultimately, it is revealed that intermolecular interactions are the core mechanism determining the optical properties and PDT efficacy of MOFs. An advanced system of MOFs based on the integration of twelve rare earth ions (RE3+) with boron dipyrromethene (BODIPY)‐derived ligands is reported. Intriguingly, this series of MOFs exhibits a reverse relationship between the radius of RE3+ and PDT efficacy. Single‐crystal X‐ray diffraction analyses along with theoretical calculations indicate that varying RE3+ results in a spatial displacement of the ligands along the dipole direction, diminishing electrostatic (dipole–dipole) interactions while enhancing dispersion (π–π) interactions, thereby enhancing the generation of triplet excitons. Consequently, a novel parameter, Ae‐v = EvdW / Eint × 100%, is proposed to quantify the interplay between non‐radiative energy dissipation via electrostatic interactions and efficient energy utilization in generating singlet oxygen through dispersion interactions. Furthermore, with consistent acoustic sensitivity aligned with the sonoluminescence mechanism, RE‐DCBs are employed in sono‐photodynamic cancer therapy, attaining significant therapeutic results in tumor treatment during in vivo experiments.

Solvent‐Induced Polyelectrolyte Conjugation for Fluorescence‐Dependence Solvent Detection

Shi,

Shao,

Wang

et al. 2024

Solvated assembly and fluorescence are two distinct features of conjugated polyelectrolytes for remarkable optoelectronic properties. However, the essential correlation between solvated assembly and fluorescence properties is still undiscovered. Here, two homopolymers based on benzotriazole (BTz) backbones with pyridinium cation‐pendants (PBTz‐PyrBr) and quaternary amine cation‐pendants (PBTz‐TMABr) are designed to distinguish fluorescence response in polar solvents, which evokes a novel application in fluorescence‐dependence solvent detection. The conjugated backbones offer orderly aligned electron‐rich nitrogen atoms to chemically react with the quaternary amine cation‐pendants for creating a space conjugation, serving as a fluorescence sensing site in polar solvents. In low‐polarity solvents, conjugated chains tend to twist and aggregate, accompanied by the space‐conjugation enhancement. This behavior increases the fluorescence performance by suppressing both inter‐ and intra‐molecular charge transfer. Furthermore, a theoretical linear‐correlation is established between fluorescence and solvent polarity/concentration to elucidate the experimental rule, giving a robust opportunity for solvent detection.