Lead sulfide (PbS) quantum dots (QDs) have attracted a great deal of attention in recent decades, due to their value for applications in optoelectronic devices. However, optimizing the performance of optoelectronic devices through ligand engineering has become a major challenge, as the surfactants that surround quantum dots impede the transport of electrons. In this paper, we prepared PbS QD films and photoconductive devices with four different ligands: 1,2-ethylenedithiol (EDT), tetrabutylammonium iodide (TBAI), hexadecyl trimethyl ammonium bromide (CTAB), and sodium sulfide (Na2S). A series of characterization studies confirmed that using the appropriate ligands in the solid-state ligand exchange step for thin film fabrication can significantly improve the responsivity. The devices treated with sodium sulfide showed the best sensitivity and a wider detection from 400 nm to 2300 nm, compared to the other ligand-treated devices. The responsivity of the champion device reached 95.6 mA/W under laser illumination at 980 nm, with an intensity of 50 mW/cm2.
Due to the ongoing depletion of fossil energy, alternative energy-sources and their respective conversion technologies have become very essential. An inexhaustible and clean energy form, which is already widely used, is solar energy. However, despite much progress in recent decades, due to the limitations of materials and manufacturing technology, the ability of solar cells to convert light into electrical energy is still not very high. Enhancing light absorption and reducing electric loss are the keys to improving the overall conversion efficiency of solar cells and reducing raw material costs. The former can be achieved by using micro/nanostructures and other surface features, while the latter can be realized by surface passivation. Researchers have developed different silicon-surface texturing methods to fabricate random or periodic micro/nanostructures on the surface of silicon wafers. Thanks to the special and efficient light-trapping effects of silicon micro/nanostructures, both full angle and wideband light absorption can be achieved. Different passivation methods and materials have also been widely studied, which helps to improve the surface recombination of photogenerated carriers caused by light trapping structure and significantly enhance the power conversion efficiency of Si solar cells. In this work, theoretical studies of enhanced light-trapping in micro/nanostructures are introduced. In addition, several advanced methods for preparing micro/nanostructures on the surface of monocrystalline silicon are discussed. These can be classified as top-down and bottom-up approaches. Furthermore, passivation methods for micro/nanostructures on the surface of monocrystalline silicon solar cells are reviewed, including chemical passivation and field-effect passivation. Finally, advantages and disadvantages of the micro/nanostructure preparation technologies, and light-trapping effects of the micro/nanostructures, which were fabricated using these manufacturing technologies were summarized. Moreover, the effects of different passivation technologies on the optical properties and electrical properties of these micro/nanostructures are studied. An outlook of expected and emerging research directions for monocrystalline silicon solar cells concludes this study.
MoSe2 and Bi2Se3 are two kinds of 2D materials that are gradually receiving more attention because of their unique electronic and optical properties. Herein, a Bi2Se3/MoSe2 van der Waals heterojunction (vdWH) is constructed and the electronic and optical properties of the heterojunction are calculated using first‐principles calculations. The effects of the external electric field and the interlayer distance on the electronic properties of the heterojunction are also studied. The calculated results show that the inherent Bi2Se3/MoSe2 vdWH has a type‐2 band alignment with a very small indirect bandgap (28 meV). It also has strong spin–orbit coupling effects, and the characteristics of Zeeman splitting and Rashba splitting are observed at the same time. Both applying an external electric field and changing the interlayer distance can effectively modulate the band structure of the heterojunction; these modulation methods can change the band alignment of the vdWH from type‐2 to type‐3 or even type‐1, and the bandgap type can be changed from indirect to direct. The infrared absorption of the heterojunction is much higher than that of Bi2Se3 and MoSe2. All the calculation results show that the Bi2Se3/MoSe2 vdWH has good application prospects in optoelectronic and spintronic devices.
Background. Proximal junction kyphosis (PJK) is the postsurgical radiographic event seen in the surgical plane after the fusion of a spinal deformity. Unfavorable health outcomes have been reported in symptomatic PJK patients compared to non-PJK patients. Methods. The data for adult scoliosis patients who underwent curve correction were extracted from the hospital database. Pelvic and spinal parameters were measured and calculated to compare four predictive formulae for occurrences of PJK. Formula 1. Restoration of hypothetical values of lumbar lordosis (LL) and thoracic kyphosis (TK) according to pelvic incidence (PI). Formula 2. Evaluation of global sagittal alignment. Formula 3. Restoration of the apex of LL to its hypothetical position according to the spine shape. Formula 4. Evaluation of positive-sum and negative-sum of (LL + TK). Results. A total number of cases were 52. There were 14 cases of PJK. The incidence of PJK was 26.9%, and the mean age for PJK cases was 63.2 ± 5.2. The excellent predictor for occurrences of PJK was formula 3. Postsurgical sagittal apexes of lumbar lordosis were located in their hypothetical position in 24 cases, and 12.5% of these cases developed PJK. While sagittal apexes were not located in their hypothetical position in 28 patients, PJK occurred in 39.3% of them ( P = 0.03 , OR: 4.53, (95% CI: 1.09–18.9)). The second good predictor for occurrences of PJK was formula 2 (GSA >45° versus GSA <45° OR = 2.5, (95% CI: 0.67–9.38), P = 0.17 ). The other two formulae (1 and 4) were not good predictors for occurrences of PJK. Conclusion. Among the four proposed formulae for predicting occurrences of PJK, the position of the sagittal apex of lumbar lordosis is an excellent predictor of the development of PJK, followed by GSA. Hypothetical values of LL and TK, and positive or negative-sum of (LL + TK), are weak predictors for occurrences of PJK.
We introduce germanium sulfide (GeS) as a new layered material for fabrication of two-dimensional van der Walls materials and heterostructures. Heterostructures of WS2/GeS were fabricated by mechanical exfoliation and dry...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.