Wafer-Scale Two-Dimensional Molybdenum Diselenide Phototransistor Array via Liquid-Precursor-Assisted Chemical Vapor Deposition

Monolayer transition metal dichalcogenides (TMDs) have received considerable interest as a candidate material for ultrathin photodetectors, but their practical applications are hindered by difficulties in synthesizing high-quality films over centimeter-scale areas. Although chemical vapor deposition (CVD) based on liquid-phase precursors has shown promise for large-area synthesis of TMDs, the resulting films typically exhibit much lower optoelectronic performance due to the lack of wafer-scale uniformity with monolayer thickness and inferior electrical properties induced by defects. In this article, the authors present a wafer-scale, gate-tunable photodetector array from high-quality monolayer molybdenum diselenide (MoSe2) films synthesized with the liquid-phase CVD process assisted by a growth promoter. Continuous monolayer MoSe2 can form by introducing potassium iodide as a growth promoter for selenizing the metal-precursor film. Side-by-side comparison between MoSe2 formed with and without the potassium iodide reveal that the promoter-assisted growth strategy significantly improves the crystallinity, which results in enhanced optoelectronic properties. The resulting photodetector array is highly photosensitive over the visible wavelengths with photoresponsivities higher than those of the previously reported devices based on CVD-synthesized monolayer TMDs and even comparable to the devices fabricated from mechanical exfoliation approach

Electrochemically exfoliated phosphorene nanosheet thin films for wafer-scale near-infrared phototransistor array

© 2022, The Author(s).Two-dimensional (2D) black phosphorus (BP), or phosphorene, has recently emerged as a promising 2D semiconductor because of its p-type charge transport behavior and near-infrared photoresponsivity. However, the application of BP in practical electronic and optoelectronic devices is hindered by challenges in producing high-quality BP films over large areas. In this manuscript, we present a facile solution-based process to create wafer-scale BP films for fabrication of p-channel field-effect transistors that are responsive to near infrared light. Few-layer BP nanosheets are first exfoliated from the bulk crystal via electrochemical intercalation of cationic molecules and then vacuum-filtered through an anodic aluminum oxide membrane. The resulting BP film can be transferred onto an SiO2-coated silicon substrate, thereby allowing for realization of field-effect transistors after electrode deposition and thermal annealing. The transistor array exhibits spatial uniformity in electrical performance with an average hole mobility of ~0.002 cm2 V−1 s−1 and on/off ratio of 130. Furthermore, gate-induced modulation of the BP channel allows for enhancement in the photoresponsivity for 1550-nm light illumination up to 24 mA W−1, which benefits the application of the phototransistor array for near infrared imaging.11Nsciescopu

The Effect of Mesenchymal Stem Cells on Dry Eye in Sjogren Syndrome Mouse Model

Sjögren’s syndrome (SS) is a systemic autoimmune disease delineated by chronic lymphocytic infiltrates into the lacrimal or salivary glands, leading to severe dry eye and dry mouth. Mesenchymal stem cells have been shown to be effective in treating numerous autoimmune diseases. This study aimed to illustrate the effects of mesenchymal stem cells on the attenuation of dry eyes (DE) through the inhibition of autophagy markers in a SS mouse model. NOD/ShiLtJ female mice with developed DE were treated with either subconjunctival or lacrimal gland injections of hMSCs (Catholic MASTER Cells). After maintenance for 14 days, clinical DE markers such as tear secretion and corneal staining were observed, as well as goblet cell counts in the conjunctiva, infiltration of inflammatory foci, B and T cells, and autophagy markers in the lacrimal glands. Proinflammatory cytokine expressions of the cornea and conjunctiva, as well as the lacrimal glands, were examined. Clinical markers, such as tear secretion and corneal stain scores, goblet cell counts in the conjunctiva, and foci infiltrations in the lacrimal glands were attenuated in mice treated with subconjunctival or lacrimal gland injections of hMSCs compared to the PBS-treated control group. B cell marker B220 decreased in the lacrimal glands of hMSCs-treated mice, as well as reduced proinflammatory cytokine expressions in the lacrimal glands and cornea. Notably, expression of autophagy markers ATG5 and LC3B-II, as well as HIF-1α and mTOR which play roles in the pathways of autophagy modulation, were shown to be attenuated in the lacrimal glands of hMSCs-treated mice compared to the PBS-treated control mice. Treatment with hMSCs by lacrimal gland or subconjunctival injection demonstrated the alleviation of DE through the repression of autophagy markers, suggesting the therapeutic potentials of hMSCs in a SS mouse model