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T. O. Oskolkova

Publications and source records attributed to T. O. Oskolkova.

2 recordsLinked to original sources

Room-temperature local strain control of moiré excitons in MoS$_2$/WSe$_2$ heterobilayers

Moiré superlattices in heterobilayers of atomically thin transition metal dichalcogenides provide a versatile platform for exploring quantum many-body physics as they can trap excitons, leading to the formation of quantized moiré exciton states. However, such moiré excitons have been predominantly studied at cryogenic temperatures, which severely limits their practical applications. Here, we demonstrate room-temperature activation and control of moiré excitons in MoS$_2$/WSe$_2$ heterobilayers using local strain engineering. Applying mechanical strain with a modified atomic force microscopy tip, we observe a series of resonances attributed to interlayer exciton states confined in the moiré potential. Power-dependent photoluminescence measurements elucidate the population dynamics of the moiré exciton states, while controlled local strain enables continuous tuning of their emission wavelength to the center of the second telecom window. We provide a theoretical model that captures all experimentally observed features, including the unconventional spectral shape of the moiré exciton emission. Our findings establish local tip-induced strain as a powerful tool for the on-demand manipulation of moiré excitons, paving the way for room-temperature quantum excitonic devices.

cond-mat.mes-hall↗

FRET-Amplified Singlet Oxygen Generation by Nanocomposites Comprising Ternary AgInS$_2$/ZnS Quantum Dots and Molecular Photosensitizers

Antibacterial photodynamic therapy (a-PDT) has emerged as a promising non-invasive therapeutic modality that utilizes the combination of a photosensitive agent, molecular oxygen, and excitation light to generate reactive oxygen species (ROS), demonstrating remarkable activity against multidrug-resistant bacterial infections. However, the effective use of conventional photosensitizers is significantly limited by a number of their shortcomings, namely, poor water solubility and low selectivity. Herein, we present a novel biocompatible water-soluble nanocomposite based on hydrophobic tetraphenylporphyrin (TPP) molecules and hydrophilic ternary AgInS$_2$/ZnS quantum dots incorporated into a chitosan matrix as an improved photosensitizer for a-PDT. We demonstrated that TPP molecules could be successfully transferred into chitosan solution while remaining primarily in the form of monomers, which are capable of singlet oxygen generation. We performed a detailed analysis of the Förster resonance energy transfer (FRET) between quantum dots and TPP molecules within the nanocomposite and proposed the mechanism of the singlet oxygen efficiency enhancement via FRET.

physics.optics↗