Search Results (3)

This study proposes an innovative design strategy for molybdenum disulfide (MoS₂) optoelectronic devices based on three-dimensional folded configurations. A “Z”-shaped folded MoS₂ device was fabricated through mechanical exfoliation combined with a pre-strain technique on elastic substrates. Experimental investigations reveal that the geometric folding deformation induces novel photocurrent response zones near folded regions beyond the Schottky junction area via band structure reconstruction, achieving triple polarity switching (negative–positive–negative–positive) of photocurrent. This breakthrough overcomes the single-polarity separation mechanism limitation in conventional planar devices. Scanning photocurrent microscopy demonstrates a 40-fold enhancement in photocurrent intensity at folded regions compared to flat areas, attributed to the optimization of carrier separation efficiency through a pn junction-like built-in electric field induced by the three-dimensional configuration. Voltage-modulation experiments show that negative bias (−150 mV) expands positive response regions, while +200 mV bias induces a global negative response, revealing a dynamic synergy between folding deformation and electric field regulation. Theoretical analysis identifies that the band bending and built-in electric field in folded regions constitutes the physical origin of multiple polarity reversals. This work establishes a design paradigm integrating “geometric deformation-band engineering” for regulating optoelectronic properties of two-dimensional materials, demonstrating significant application potential in programmable photoelectric sensing and neuromorphic devices. Full article

In order to improve the charge transfer properties and reduce the recombination of photogenerated carriers, an Fe₂O₃/C₃N₄ heterojunction was constructed to increase the built-in field. The grain boundary of the Fe₂O₃/C₃N₄ nanocomposite was filled with Cu, Au, Pt, and Pd nanoparticles using in situ synthesis. The nanometal-modified heterostructures showed good absorption in the visible and near-infrared (NIR) regions. The photocurrent responses to the light sources with wavelengths of 405, 532, 650, 780, 808, 980, and 1064 nm were investigated using Au electrodes. The results indicated that the nanocomposite exhibits photocurrent switching behaviour towards the visible-light and NIR regions. Interestingly, the reversible photocurrent response phenomenon (transition from negative to positive photoconductivity) was observed before and after passivation of the grain boundary defects of the Fe₂O₃/C₃N₄ heterojunction with metal nanoparticles. The physical mechanisms involved were discussed. The Cu nanomaterials played donor effects in the interfacial tailoring of the Fe₂O₃/C₃N₄ heterojunction since Cu nanoparticles possess a high concentration of free electrons. It was shown that defects in the nanocomposites play an important role in the photoelectric behaviour and that modulation of the defects not only enhances photocurrent acquisition but also determines the polarity of the photocurrent. This study provides useful guidance not only for microstructure modulation and interdisciplinary applications of the materials themselves but also for the study of light–matter interactions. Full article

Transformation into electric or photoelectric functional composite from non-conjugated polymers is a great challenge due to the presence of a large number of locative states. In this paper, carbon nanofiber was synthesized via hydrothermal carbonization utilizing carboxymethyl cellulose as a precursor, and the carbon nanofiber/Cu nanocomposite was constructed for defect passivation. The results indicated that the resulting nanocomposites exhibited good absorbance in visible light range and NIR (near-infrared). The photoconductive responses to typical weak visible light (650 nm et al.) and NIR (808, 980, and 1064 nm) were studied based on Au gap electrodes on flexible polymer substrates. The results exhibited that the nanocomposite’s solid thick film showed photocurrent-switching behaviors to visible light and NIR, the switch-ratio was depending on the wavelengths and power of incident lights. The positive and negative photoconductance responses phenomenon was observed in different compositions and changing excited wavelengths. Their photophysical mechanisms were discussed. This illustrated that the nanocomposites easily produce free electrons and holes via low power of incident light. Free electrons and holes could be utilized for different purposes in multi-disciplinary fields. It would be a potential application in broadband flexible photodetectors, artificial vision, simulating retina, and bio-imaging from visible light to NIR. This is a low-cost and green approach to obtain nanocomposite exhibiting good photocurrent response from the visible range to NIR. Full article