MXene V₂CT_x Nanosheet/Bismuth Quantum Dot-Based Heterostructures for Enhanced Flexible Photodetection and Nonlinear Photonics

Abstract

Recently, novel two-dimensional materials, e.g., Xenes (graphdiyne, phosphorene, bismuthene, antimonene, etc.) and MXenes, have drawn great attention in nanophotonics due to their excellent flexibility, high photothermal conversion efficiency, and large thermal conductivity. Although the Xenes and MXenes have achieved rapid progress in many fields over the past decade, their relatively poor photodetection and nonlinear photonics have still limited their practical applications. In this work, a mixed-dimensional 2D MXene V2CT x nanosheet (NS)/0D bismuth quantum dot (Bi QD)-based heterostructure fabricated by a combination of selective etching and the hydrothermal method was simply deposited onto a clean poly­(ethylene terephthalate) substrate with an embedded regular Ag lattice to prepare a flexible photoelectrochemical (PEC) electrode. The PEC result shows that the as-fabricated flexible electrode not only exhibits significantly improved photocurrent density (32.7 μA cm–2) and photoresponsivity (906 μA W–1) compared to individual MXene V2CT x NSs and Bi QDs but also displays high stability with a stable photocurrent density even after 200 bending cycles at 60°. Taking advantage of the Kerr effect of both MXene V2CT x NSs and Bi QDs, an all-optical switcher based on this mix-dimensional heterostructure for the spatial cross-phase modulation has also been realized with a preferred modulation depth. Density functional theory calculations provide direct evidence for the strong internal built-in electric field (7.3 × 107 eV m–1) created by the heterostructure for the enhancement of both photodetection and nonlinear photonics. The integration of Xenes or MXene-based mixed-dimensional heterostructures provides a concept and fundamental guidance to construct next-generation optoelectronic and photonic devices.

Novel rod‐like carbon nanomaterials as near infrared‐responsive drug delivery system for potential anticancer applications

“…The novel RCNs were synthesized by the soft‐template hydrothermal method. As indicated in the TEM and High Resolution (HRTEM) image [35–37] (Figure 1), it was apparently demonstrated that the products were constituted principally by rod‐shaped carbon particles with relatively uniform dispersion and regular particle size. And the average size of the carbon rods was measured to be approximately 85 to 120 nm in length, and 35 to 50 nm in width.…”

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

“…Similarly, the nanoscale thinning process and structural design, including serpentine, − fractals, − buckling, − and liquid metals, − have been explored for developing flexible and stretchable electrodes. For active materials, several approaches, including nanodimensional materials, , structural engineering, ,− organic materials ,− and hybrid composites, − are introduced to implement the PDs with great flexibility/stretchability and high performance simultaneously. Representative flexible/stretchable PDs with performance parameters are summarized in Table .…”

Chloroplast-Inspired Carrier Circulation for Improved Photoelectrochemical Photodetectors Based on Ti2CTx Nanosheets

“…Two-dimensional (2D) layered materials exhibit remarkable physicochemical features, such as improved optical transparency, exceptional electrical conductivity, and superior mechanical strength. − Transition-metal carbides and/or nitrides, also referred to as MXenes, are a new class of 2D materials that possess a number of endearing qualities, including metallic conductivity, mechanical flexibility, hydrophilia, great transmittance, and chemical stability. − In particular, Ti 2 CT x , as one of the many varieties of MXenes, exhibits remarkable semiconducting behavior in terms of strong light absorption in the visible range due to a band gap of 2.32 eV. , Additionally, it has ultrahigh hole mobility of 3.36 × 10 4 cm 2 V –1 s –1 and superhigh carrier mobility of 1 × 10 4 cm 2 V –1 s –1 , which are the highest in the MXene family. − Due to these outstanding electrical and optical properties, Ti 2 CT x is a great candidate for constructing large-area, ultraflexible, high-performance photodetectors. − However, the recombination of photogenerated electron–hole pairs has largely restricted the performance of 2D semiconductor photodetectors, including MXene photodetectors. − To solve this problem, the optical and electrical properties of MXene have been optimized using a variety of methods to improve their photoresponse performance. , Luo et al created van der Waals Schottky junction and chose metal electrodes to adjust MXene as a suitable charge transport layer, and Yu et al increased the specific surface area and active sites of MXene nanosheets by a liquid-phase exfoliation method to improve the photoelectric conversion capability of MXene, respectively. Despite this, due to the limitations of the structure and materials of the photodetector itself, these improvements are relatively limited.…”