Confined-domain crosslink-enhanced emission effect in carbonized polymer dots

Revealing the photoluminescence(PL)origin and mechanism is a most vital but challenging topic of carbon dots.Herein,confined-domain crosslink-enhanced emission(CEE)effect was first studied by a well-designed model system of carbonized polymer dots(CPDs),serving as an important supplement to CEE in the aspect of spatial interactions.The“addition-condensation polymerization”strategy was adopted to construct CPDs with substituents exerting different degrees of steric hindrance.The effect of confined-domain CEE on the structure and luminescence properties of CPDs have been systematically investigated by combining characterizations and theoretical calculations.Such tunable spatial interactions dominated the coupling strength of the luminophores in one particle,and eventually resulted in the modulated PL properties of CPDs.These findings provide insights into the structural advantages and the PL mechanism of CPDs,which are of general significance to the further development of CPDs with tailored properties.

A three-dimensional measurement method for binocular endoscopes based on deep learning

In the practice of clinical endoscopy,the precise estimation of the lesion size is quite significant for diagnosis.In this paper,we propose a three-dimensional(3D)measurement method for binocular endoscopes based on deep learning,which can overcome the poor robustness of the traditional binocular matching algorithm in texture-less areas.A simulated binocular image dataset is created from the target 3D data obtained by a 3D scanner and the binocular camera is simulated by 3D rendering software to train a disparity estimation model for 3D measurement.The experimental results demonstrate that,compared with the traditional binocular matching algorithm,the proposed method improves the accuracy and disparity map generation speed by 48.9%and 90.5%,respectively.This can provide more accurate and reliable lesion size and improve the efficiency of endoscopic diagnosis.

Thermally Activated Delayed Fluorescence of Aggregates Induced by Strongπ–πInteractions and Reversible Dual-Responsive Luminescence Switching

A reversible dual-responsive luminescent material was introduced by our group to show the simultaneous color and lifetime switching in response to external stimuli.Pristine crystalline powder of(E)-2-(benzo[d]thiazol-2-yl)-3-(pyren-1-yl)acrylonitrile(Py-BZTCN)shows the orderedπ–πstacking with only near-monomer-normal orange-yellow fluorescence,but it exhibits red emission with thermally activated delayed fluorescence(TADF)after grinding,which can be reversibly recovered by heating or fuming treatment.Grinding disturbs the orderedπ–πstacking of pristine powder,leading to the formation of small aggregates with compressed distance and increased overlap ofπ–πstacking between adjacent molecules.The cause of switching was verified by single-crystal X-ray diffraction experiments of two corresponding crystals.This strongπ–πinteraction effectively promotes the excited-state energy splitting and substantially decreases the singlet–triplet energy gap(ΔEST)of aggregates,resulting in the red TADF emission of aggregates through reverse intersystem crossing.This finding proposes a new route to realizing the TADF emission of aggregates through strong intermolecular interactions based on non-TADF monomer,thereby enabling a novel high-contrast dualresponsive luminescence switching.