arXiv subjects

Petr Rozhin

Publications and source records attributed to Petr Rozhin.

2 recordsLinked to original sources

arXiv2026

Highly Efficient Exciton Modulation in MoSe$_2$/PdSe$_2$ Heterostructures

Controlling exciton recombination in atomically thin semiconductors is central to their optoelectronic functionality, as the competition between radiative and non-radiative decay channels governs emission efficiency. Existing approaches, such as defect passivation, chemical doping, dielectric engineering, and strain tuning, primarily aim to suppress non-radiative losses. Here, we report a pronounced $\sim$6-fold enhancement of room-temperature A-exciton emission in a type-I MoSe$_2$/PdSe$_2$ van der Waals heterostructure, yielding a photoluminescence quantum yield of 6 %, compared to $\sim$1 % for as-exfoliated monolayer MoSe$_2$. This enhancement is accompanied by strong quenching of the B-exciton, consistent with interlayer electronic coupling that redistributes exciton populations toward the radiative A-exciton channel. Power- and temperature-dependent measurements reveal a suppression of exciton-exciton annihilation and a crossover to quenched emission at low temperature, indicating a redistribution of exciton relaxation pathways. Photoluminescence excitation spectroscopy further reveals a broadband enhancement spanning 450-725 nm, ruling out a resonance-specific mechanism. These results demonstrate that interlayer electronic coupling can be used as an efficient means to redirect exciton populations toward radiative channels, enhancing emission efficiency in two-dimensional semiconductors without chemical modification or strain.

cond-mat.mes-hall↗

arXiv2025

Broadband, Flexible, Skin-Compatible Carbon Dots/Graphene Photodetectors for Wearable Applications

The development of wearable photodetectors demands a unique combination of broadband optical sensitivity, mechanical flexibility, and skin-compatibility, with these requirements rarely met simultaneously by existing technologies. Here, we present photodetectors that combine all of these performances. This is achieved by integrating carbon dots, engineered for extended ultraviolet-to-near-infrared absorption, with single-layer graphene transferred onto a plastic substrate. Unlike traditional quantum dot systems, our carbon dots achieve a broad ultraviolet-to-near-infrared response without toxic heavy metals. Graphene provides an efficient channel for charge transport, while a biocompatible chitosan-glycerol electrolyte enables efficient, low-voltage carrier modulation, with peak performance at approximately 0.5 V gate bias. The resulting photodetectors exhibit a broadband photoresponse with responsivities of approximately 0.19 A/W at 406 nm, 0.32 A/W at 642 nm, and 0.18 A/W at 785 nm. They maintain consistent performance at a bending radius of 0.8 cm with negligible degradation after repeated cycles. Furthermore, skin-compatibility assessments using the SkinEthic model confirm the non-toxic nature and suitability of our devices for direct skin contact. The combination of broadband absorption (400-800 nm), flexibility, and skin-compatibility, along with low-voltage operation ($<$ 1.5 V), positions our photodetectors as promising building blocks for next-generation wearable optoelectronics.

cond-mat.other↗