Search

In this paper, high-performance CuSCN/Si heterojunction near-infrared photodetectors were successfully prepared using nanoscale light-trapping optical structures. Various light-trapping structures of ortho-pyramids, inverted pyramids and silicon nanowires were prepared on silicon substrates. Then, CuSCN films were spin-coated on silicon substrates with high crystalline properties for the assembly of CuSCN/Si photodetectors. Their reflectance spectra and interfacial passivation properties were characterized, demonstrating their superiority of light-trapping structures in high light response. Under the irradiation of 980 nm near-infrared light, a maximum responsivity of 2.88 A W−1 at −4 V bias and a specific detectivity of 5.427 × 1010 Jones were obtained in the CuSCN/Si heterojunction photodetectors prepared on planner silicon due to 3.6 eV band gap of CuSCN. The substrates of the light-trapping structure were then applied to the CuSCN/Si heterojunction photodetectors. A maximum responsivity of 10.16 A W−1 and a maximum specific detectivity of 1.001 × 1011 Jones were achieved under the 980 nm near-infrared light irradiation and −4 V bias, demonstrating the advanced performance of CuSCN/Si heterojunction photodetectors with micro-nano light-trapping substrates in the field of near-infrared photodetection compared to other silicon-based photodetectors. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • Self-powered MoS 2 /Si flexible photodetectors with Al 2 O 3 interface were developed. • The vertical MoS 2 nanofilms were grown by RF magnetron sputtering and Al 2 O 3 by ALD. • The photodetectors could be bent up to 120° and worked well after 200 bending times. • R of 0.047 A/W and D* of 5.67 × 1011 Jones were obtained under 980 nm with 200 μW/cm2. The self-driven flexible photodetector is vitally important for next-generation optoelectronics. Two-dimensional (2D) molybdenum sulfide (MoS 2) as a typical family member of transition-metal dichalcogenides (TMDs) has shown larger potential applications in the high-sensitivity photodetection due to its self-physical properties. Herein, the ultrafast MoS 2 /Si flexible photodetector with ultrathin Al 2 O 3 passivation interface and high light-trapping structures was fabricated. The MoS 2 /Al 2 O 3 /Si flexible photodetector exhibits excellent performance with a high responsivity of 0.047 A/W, detectivity up to 5.67 × 1011 Jones and rise/fall time of 25.6/3.2 μs. Furthermore, this optoelectronic device can withstand bending angles of 120° and work well after 500 bending times. This unique performance can be attributed to the flexible Si substrate with good mechanical properties, high-light trapping structures and an Al 2 O 3 passivation interface. This device can find potential applications in e-skins, flexible displays and smart health care. [ABSTRACT FROM AUTHOR]

In this work, fast response and broadband self-powered photodetectors based on heterojunctions of vertical smooth silicon nanowires (SiNWs) were proposed, which were achieved through spin-coating p-CZTS on top of n-SiNWs adopting a simple two-step method. First, CZTS was uniformly and tightly attached to the sidewalls of SiNWs in the form of nanoparticles. The prepared CZTS/SiNWs core-shell heterojunctions exhibited typical rectification characteristics in dark and excellent light response characteristics in light illumination. Our device could perform self-driven detection under the UV-VIS-NIR light irradiation without an external energy supply. The responsivity and specific detectivity were estimated to be 14 mAW-1 and 1.5 × 1011 Jones, which can be improved to 0.35 AW-1 and 1.2 × 1013 Jones at −1.5 V bias. In addition, the present device also possesses distinct advantages of a large I light /I dark ratio exceeding 4.25 × 104, fast response rate with rise/fall times of 1.4/14.2 μs, and outstanding environmental stability. Finally, a heart rate health monitoring application by CZTS/SiNWs detector was proposed. All these results may pave a way for the real application of the self-driven detector in the field of health monitoring in the future. [ABSTRACT FROM AUTHOR]

A novel nanomaterial formed by a Cu2ZnSnS4 (CZTS)/CeO2 heterojunction with excellent electrochemical sensing for ammonia nitrogen was prepared by a microwave irradiation method combined with a hydrothermal method. The properties of the CZTS/CeO2 heterojunction were investigated by a series of characterizations such as Raman spectra, x-ray diffraction, scanning electron microscopy, thermogravimetric analysis, specific surface area (SSA), temperature-programmed desorption of ammonia and UV–vis spectroscopy. Nickel foam was used as a conductive frame electrode in order to enhance the sensitivity of the sensor along with the electrical conductivity, permeability and SSA. It is revealed by electrochemical measurements that the ammonia nitrogen oxidation reaction occurring in the sensing electrode of the CZTS/CeO2 heterojunction demonstrated regulation of Ip (mA) = 6.4 × 10−3C (mM)+ 0.1527 (R2= 0.9987) in a wide concentration range of 0–380.0 mM with a low detection of 6.0 μM according to the signal-to-noise ratio (S/N= 2). The CZTS/CeO2 heterojunction is expected to become a new candidate semiconductor nanomaterial for the electrochemical detection of ammonia nitrogen in an aqueous solution. [ABSTRACT FROM AUTHOR]

The most effective and potential approach to improve the performance of heterojunction photodetectors is to obtain favorable interfacial passivation by adding an insertion layer. In this paper, MoOx/Al2O3/n-Si heterojunction photodetectors with excellent photocurrents, responsivity and detectivity were fabricated, in which alumina acts as a tunneling passivation layer. By optimizing the post-annealing treatment temperature of the MoOx and the thickness of the ultra-thin Al2O3, the photodetector achieved a ratio of photocurrent to dark current of 3.1 × 105, a photoresponsivity of 7.11 A W−1 (@980 nm) and a detective of 9.85 × 1012 Jones at −5 V bias. Besides, a self-driven response of 0.17 A W−1 and a high photocurrent/dark current ratio of 2.07 × 104 were obtained. The result demonstrated that optimizing the interface of heterojunctions is a promising way to obtain a heterojunction photodetector with high-performance. [ABSTRACT FROM AUTHOR]

• Novel WO 3 -TiO 2 /CZTS ternary photocatalyst was prepared via hydrothermal method. • CO 2 photoreduction performance of ternary photocatalyst improved remarkably. • Large surface area and effective charge separation increased the yield rates of CO/CH 4. • The WO 3 -TiO 2 /CZTS ternary photocatalyst showed excellent stability. To date, the rapid increase of the CO 2 concentration in the Earth's atmosphere is one of the primary causes of global warming, which leads to other environmental issues; however, the photocatalytic CO 2 reduction is a process that offers environmental protection and valuable solar fuels generation simultaneously. Yet, the high CO 2 activation barrier and inefficient proton supply are the main challenges, which substantially hamper the photo-conversion efficiency over heterogeneous catalysts. Herein, a Z-scheme mesoporous WO 3 -TiO 2 /CZTS ternary photocatalyst was synthesized through a two-stage strategy, and the photoreduction of CO 2 with H 2 O vapor was carried out under the visible light irradiation. A synergistic effect among WO 3 , TiO 2 and CZTS over CO 2 reduction was observed by anchoring the CZTS over WO 3 -TiO 2 nanocomposite. The ternary composite showed the enhanced CO/CH 4 yield rates of 15.37/1.69 μmol h−1 g−1, which was significantly higher than that of pristine TiO 2 (0.44/0 μmol h−1 g−1) and WO 3 -TiO 2 composite (5.39/ 0.34 μmol h−1 g−1), attributing the high surface area with greater light absorption and suppressed the electron–hole recombination as a result of the intrinsic p–n heterojunction nature of the material. The apparent quantum efficiency was estimated to be 0.52 %. In addition, the possible reaction mechanism and pathways of photocatalytic CO 2 reduction with H 2 O over heterogeneous catalysts were also presented. [ABSTRACT FROM AUTHOR]

• CuS films were prepared by e-beam evaporation of Cu films as precursor layers. • n-type Si wafers with inverted pyramid were used to enhanced device performance. • The CuS/n-Si PDs showed a self-driven R of 0.41 A/W and a rise time of 17 μs. • The CuS/n-Si heterojunction PDs demonstrated an EQE of 51.91% at 980 nm. Transition metal dichalcogenides (TMDCs) are considered to be the most promising next-generation materials for electronics and optoelectronics due to their excellent properties. In this work, well-performing CuS films were prepared by e-beam evaporation of Cu films as precursor layers. Ag/n-Si/Al 2 O 3 /CuS/ITO heterojunction photodetector with high responsivity (0.41 A·W−1), detectivity (1.739 × 1011 Jones) and fast response speed (17 μs) at zero bias were prepared by optimising sulphuration temperature and using silicon wafers with inverted pyramid light-trapping structures as substrates. Besides, the photodetector exhibited excellent light absorption ability, with an EQE of 51.91% at 980 nm. All these results demonstrated that excellent photodetector materials can be obtained by using metal films as precursor layers, which provides novel ideas and methods for the synthesis of TMDCs materials. [ABSTRACT FROM AUTHOR]

In this paper, we present the result of heterojunction solar cells based on porous silicon layer transfer technology. a-Si/c-Si structured solar cells were prepared in which the c-Si was deposited on annealed double-layer porous silicon by low-pressure chemical vapor deposition. The structural properties and the evolvement of the double-layer porous silicon before and after thermal annealing were investigated by scanning electron microscopy. X-ray diffraction, Raman spectroscopy and a microwave photoconductive decay method were used to investigate the properties of the epitaxial silicon thin films deposited at different pressures. And, the influence of the deposition pressure on the properties of the c-silicon thin films was investigated. The spectral responses of the cells were studied by a quantum efficiency test. The results show that the epitaxial silicon thin film deposited at 100 Pa has better carrier lifetime and better spectral response. Furthermore, the Raman peak intensity of the silicon film prepared at 100 Pa is much closer to that of a monocrystalline silicon wafer. A simple solar cell structure without any light-trapping features showed an efficiency of up to 10.1 %. [ABSTRACT FROM AUTHOR]

Abstract: To explore the origin of low conversion efficiency for novel β-FeSi2/c-Si heterojunction solar cells, the effect of surface recombination and interface states on the cell performance has been investigated by numerical simulation. The present results show that surface recombination of β-FeSi2 film plays an important role in limiting the cell property since the photovoltaic behavior of β-FeSi2 is quite sensitive to surface recombination due to its especial characteristic of very high optical absorption coefficient. Surface quality of β-FeSi2 film should be much improved for better cell performance. In addition, it is shown that interface states between β-FeSi2 film and crystalline silicon are critical to device characterization. Interface states should be minimized to obtain higher conversion efficiency. If surface recombination and interface states can be best suppressed, potential conversion efficiency for the cell may be up to 28.12% at 300K under illumination of AM 1.5, 100mW/cm2. [Copyright &y& Elsevier]

Abstract: In this paper, numerical simulations on the performance of p-type β-FeSi2 emitter/n-type crystalline Si base heterojunction solar cells are carried out using PC1D software. The dependences of performance on layer thickness and doping concentration in the emitter region are analyzed. The influences of main recombination mechanisms in the emitter region for cell characterization are discussed. The simulation results show that both emitter thickness and doping concentration have very important influences on the property of β-FeSi2/c-Si heterojunction solar cells. These two parameters need to be jointly selected to improve cell performance. The optimal values of emitter thickness and doping concentration are 350nm and 2×1017 cm−3 for the cell structure, respectively. Moreover, cell efficiency can be enhanced by suppressing carrier recombination rate. Bulk and surface recombinations must be minimized by improving the material growth and surface passivation process, and the Auger and radiative recombination can be suppressed by reducing carrier concentrations appropriately. With the emitter parameter optimized, device performance can be well improved. [ABSTRACT FROM AUTHOR]

Micro and nano light-trapping structures are widely applied to improve the performance of optoelectronic devices. In this work, inverted-pyramid light trapping texture on industrial-sized p-type silicon was prepared by a rapid and repeatable one-step room-temperature Cu-MACE process. On this basis, various TMOs (transition metal oxide)-Si heterojunction photodetectors (PDs) are fabricated by a low-temperature process. After careful comparison, a ZnO/Al 2 O 3 /p-Si/Al 2 O 3 /CuO heterojunction is selected as the ideal device structure, and the corresponding work mechanism is proposed. Finally, by optimizing the Al 2 O 3 tunneling layers' thickness, a high-performance NIR PD working at 980 nm and −5 V bias stands out. The bifacial carrier selective transportation PD exhibits a considerable detectivity (5.56 × 1011 Jones) and a high responsivity (7.10 A/W). Our work will expand the application of inverted-pyramid textured silicon and will pave a road for mass fabrication of TMOs-Si heterojunction PD. • A new transition metal oxide-Si heterojunction photodetector was developed. • Photodetectors were produced on inverted-pyramid textured Si by Cu-MACE. • Improved device performance was achieved by ALD Al 2 O 3 tunneling layer. • High responsivity and good detectivity in the photodetectors were obtained. [ABSTRACT FROM AUTHOR]

• Z-scheme CZTS@Pt integrated g-C 3 N 4 heterojunction photocatalyst was developed. • Type-I straddling band offset shows the suppressed charge recombination. • Excellent CO 2 reduction was obtained under visible light. • The synergistic effect between CZTS and Pt/g-C 3 N 4 enhanced the CO 2 reduction. • A diverse mechanism was proposed to explain the high photocatalytic activity. In the context of efficient conversion of CO 2 to high-value carbonaceous fuels, the development of photocatalysts for CO 2 reduction having high solar-to-fuel energy efficiency with exceptional selectivity and long-term stability is the prime requisite of current research. Herein, we reported a novel straddling band configuration based Cu 2 ZnSnS 4 /Pt-integrated g-C 3 N 4 heterojunction photocatalyst for CO 2 reduction to carbonaceous fuels. The heterojunction photocatalyst exhibited an enhanced CO 2 reduction with an average CO/CH 4 yield rates of 17.351/7.961 μmolg−1 h−1, which is ∼3.31 and ∼5.56 folds higher than pristine g-C 3 N 4. The comprehensive analysis of heterojunction photocatalyst exhibited synergetic effects owing to higher surface area, efficient photon harvesting due to CZTS and multiple charge-transfer pathways together with Z-scheme charge transfer. Moreover, the localized surface-plasmon-resonance (LSPR) and electron sink function of Pt led to an efficient interfacial charge carrier separation, surface site activation for CO 2 reduction and in the consequence of that enhanced the photocatalytic performance. [ABSTRACT FROM AUTHOR]