Rectification Characteristics Research Articles

Super-Broadband Rectifier with Wide-band Resistance Compression Network and Harmonic Cycling for RF-Harvesting

In this paper, a super-broadband (SBB) rectifier using a wideband resistance compression network (WRCN) and harmonic cycling is proposed, simulated, fabricated, measured and analyzed in detail for the harvesting of ambient radio frequency (RF) energy. Meanwhile, impedance compression and matching are achieved to implement the SBB using WRCN and impedance operation networks. Additionally, harmonic cycling structure and bending technology are employed to improve the power conversion efficiency (PCE) and reduce the size, respectively. For demonstration, a prototype of the proposed rectifier is fabricated and measured. The measured results are in good accordance with the simulated ones, indicating that the rectifier can provide high efficiency and ultra-broadband rectification characteristics. A PCE over 50% is realized at 3.5 GHz with an input power range of 6–24 dBm, and a PCE of 75% is obtained at an input power of 18 dBm. The PCE is greater than 50% at 17 dBm with an input frequency of 2.7-4.6 GHz. This work can find significant applications in the development of RF-harvesting.

Interfacial Super-Assembly of Intertwined Nanofibers toward Hybrid Nanochannels for Synergistic Salinity Gradient Power Conversion.

Capturing the abundant salinity gradient power into electric power by nanofluidic systems has attracted increasing attention and has shown huge potential to alleviate the energy crisis and environmental pollution problems. However, not only the imbalance between permeability and selectivity but also the poor stability and high cost of traditional membranes limit their scale-up realistic applications. Here, intertwined "soft-hard" nanofibers/tubes are densely super-assembled on the surface of anodic aluminum oxide (AAO) to construct a heterogeneous nanochannel membrane, which exhibits smart ion transport and improved salinity gradient power conversion. In this process, one-dimensional (1D) "soft" TEMPO-oxidized cellulose nanofibers (CNFs) are wrapped around "hard" carbon nanotubes (CNTs) to form three-dimensional (3D) dense nanochannel networks, subsequently forming a CNF-CNT/AAO hybrid membrane. The 3D nanochannel networks constructed by this intertwined "soft-hard" nanofiber/tube method can significantly enhance the membrane stability while maintaining the ion selectivity and permeability. Furthermore, benefiting from the asymmetric structure and charge polarity, the hybrid nanofluidic membrane displays a low membrane inner resistance, directional ionic rectification characteristics, outstanding cation selectivity, and excellent salinity gradient power conversion performance with an output power density of 3.3 W/m2. Besides, a pH sensitive property of the hybrid membrane is exhibited, and a higher power density of 4.2 W/m2 can be achieved at a pH of 11, which is approximately 2 times more compared to that of pure 1D nanomaterial based homogeneous membranes. These results indicate that this interfacial super-assembly strategy can provide a way for large-scale production of nanofluidic devices for various fields including salinity gradient energy harvesting.

Ultrafast Mechanism of Material Removal in the Femtosecond Laser Ablation of WS2 and Its Diode Rectification Characteristics

The study investigates the two different underlying ablation mechanisms of WS2 processed by femtosecond (fs) laser with different fluences. With increasing fluence, the saturable expansion of craters and the transformation of three distinct crater morphologies are found. The material response and the transfer and deposition of laser energy are tracked by using a plasma model based on the classical single rate equation model and the Drude model. The results of the numerical simulation and time-resolved transient reflectivity reveal the two different ablation mechanisms, which are coulomb explosion and phase explosion. The mechanism of material removal is distinguished by the critical threshold of 0.85 J/cm2. In addition, the internal ablation region exhibits a high concentration of defects and WO3 according to the results of Raman spectra, X-ray photoelectron spectra, and morphology-dependent photoluminescence mapping. Due to the high concentration with high fluence, the device of WS2/Si p-n junction exhibits a 2.6 times enhancement on the current under forward bias. The findings would be of value to engineer structures to tailor the optoelectronic response of WS2 and to develop potential future optoelectronic devices.

Evolution of Frenkel defect pairs in β-Ga2O3 thin film with the introduction of oxygen and its application in GaN-based ultraviolet light-emitting diode

In this work, β-Ga2O3 thin films were deposited by radio frequency (RF) magnetron sputtering technique. The effect of oxygen-argon flow ratio (OAFR) on the formation of Frenkel defect pairs was systematically analyzed. The Frenkel defect pairs would become abundant when the OAFR was 25:25 sccm, resulting in a severe damage in crystalline quality and an increase in the density of disorder. With the further increase of OAFR, Frenkel defect pairs would dramatically decrease or even vanish due to the significant reduction of oxygen vacancies (V0). Immediately after that, on the basis of avoiding the influence of Frenkel defect pairs inside the β-Ga2O3 films to the devices, the p-NiO/i-Ga2O3/n-GaN diode was fabricated from the as-prepared high-quality β-Ga2O3 film after post-deposition annealing as the electron-blocking layer. Subsequently, its electrical characteristics were investigated in detail which exhibited excellent rectification characteristics under all test temperatures. Correspondingly, the device achieved electroluminescence (EL) with a dominant sharp emission peak in the ultraviolet range (∼375 nm). In the end, the energy band diagram was used for in-depth analysis of the EL mechanism.

Short-term memory characteristics in n-type-ZnO/p-type-NiO heterojunction synaptic devices for reservoir computing

We investigated the short-term memory characteristics of n-type-ZnO/p-type-NiO heterojunction-based memristor devices to achieve a reservoir computing system. The deposited thickness and chemical properties of each layer of the device were verified by transmission electron microscopy and energy-dispersive X-ray spectroscopy. The TiN/ZnO/NiO/Pt device exhibited the resistive switching behaviors of a typical p-n junction-based RRAM with rectification characteristics. The self-rectification characteristics of the device were attributed to the diode effect of the p-n junction and the redox reaction of TiON. Thus, stable and controllable multistate analog memory was obtained using gradual bipolar resistive switching during successive sweeping cycles. Moreover, excellent potentiation and depression were achieved with a stable dynamic range over 10 cycles by coordinated identical pulses. High MNIST pattern recognition accuracy (>94%) was obtained through a three-layer neural network (784 × 224 × 10); short-term memory dynamics were observed using DC current read sweep by controlling the delay time after the set process and conductance decay, such as paired-pulse facilitation, by varying the pulse interval. Finally, we constructed a reservoircomputing system with 16 states (4-bit) distinguished by varying pulse streams ranging from [0000] to [1111] using the short-term memory effects of the TiN/ZnO/NiO/Pt device.

Photosensitive Field-Effect Transistor with Enhanced Photoamplification Mediated by Charge Transfer in a Heterostructure of α- CsPbI3 Nanocrystals and Two-Dimensional WS2

Hybrid heterostructure-based phototransistors are attractive owing to their high gain induced by the photogating effect. However, the absence of an in-plane built-in electric field in the single-channel-layer transistor results in a relatively higher dark current and requires a large operating gate voltage of the device. Here, we report air-stable cesium lead iodide/tungsten di-sulfide (${\mathrm{Cs}\mathrm{Pb}\mathrm{I}}_{3}/{\mathrm{WS}}_{2}$) mixed-dimensional heterostructure-based photo-field-effect-transistors (photo-FETs) with asymmetric metal electrodes ($\mathrm{Cr}/{\mathrm{WS}}_{2}/\mathrm{Au}$), exhibiting extremely low dark current (approximately ${10}^{\ensuremath{-}12}$ A) with a responsivity of approximately ${10}^{2}$ A/W at zero gate bias. The Schottky-barrier- (${\mathrm{WS}}_{2}/\mathrm{Au}$ interface) induced rectification characteristics in the channel accompanied by the excellent photogating effect from solution-processed \ensuremath{\alpha}-phase ${\mathrm{Cs}\mathrm{Pb}\mathrm{I}}_{3}$ nanocrystal sensitizers, resulting in gate-tunable broadband photodetection with a very high responsivity (approximately ${10}^{4}$ A/W) and excellent sensitivity (approximately ${10}^{6}$). Most interestingly, the device shows superior performance even under high-humidity (50--65%) conditions owing to the formation of cubic \ensuremath{\alpha}-phase ${\mathrm{Cs}\mathrm{Pb}\mathrm{I}}_{3}$ nanocrystals with a relatively smaller lattice constant (a = 6.2315 \AA{}) and filling of surface vacancies (${\mathrm{Pb}}^{2+}$ centers) with the sulphur atoms from the ${\mathrm{WS}}_{2}$ layer, thus protecting it from environmental degradation. These results emphasize an exciting strategy for developing mixed-dimensional hybrid heterostructure-based phototransistors for futuristic integrated nano-optoelectronic systems.

Fabrication of transparent ITO/GTO bilayer diode thin films

Transparent diodes were fabricated by layering a Ga–Sn–O (GTO) film onto an In2O3:Sn (ITO) film using a facing-targeted DC sputtering method. When a GTO film containing [Formula: see text] mol% Ga was deposited on the surface of the conductive ITO film at room temperature, a diode bilayer film was obtained.The bilayer film exhibited rectification characteristics of approximately 0 and 3.8 [Formula: see text]A/V when negative and positive voltages were applied, respectively. However, the rectification characteristics increased up to 68.3 [Formula: see text]A/V in the positive voltage applied region after annealed at 200[Formula: see text]C.

High-Performance NiO/TiO2/ZnO Photovoltaic UV Detector

The ultraviolet (UV) photodetector has found many applications, ranging from optical communication to environmental monitoring. There has been much research interest in the development of metal oxide-based UV photodetectors. In this work, a nano-interlayer was introduced in a metal oxide-based heterojunction UV photodetector to enhance the rectification characteristics and therefore the device performance. The device, which consists of nickel oxide (NiO) and zinc oxide (ZnO) sandwiching an ultrathin dielectric layer of titanium dioxide (TiO2), was prepared by radio frequency magnetron sputtering (RFMS). After annealing, the NiO/TiO2/ZnO UV photodetector exhibited a rectification ratio of 104 under UV irradiation of 365 nm at zero bias. The device also demonstrated a high responsivity of 291 A/W and a detectivity of 6.9 × 1011 Jones at +2 V bias. Such a device structure provides a promising future for metal oxide-based heterojunction UV photodetectors in a wide range of applications.

A wire-shaped photoanode of the solar-blind photoelectrochemical-type photodetector based on an α-Ga2O3 nanorods/electrolyte solid/liquid heterojunction

Multifunctional and smart solar-blind photodetectors are of great significance for many applications, particularly for communications, optoelectronic circuits, and environmental risk monitoring. In this study, a wire-shaped photoanode of the solar-blind photoelectrochemical (PEC)-type photodetector based on an α-Ga2O3 nanorods/electrolyte solid/liquid heterojunction is realized. In photovoltaic devices, a junction generally comprises two different solid materials to facilitate the separation of photogenerated electron–hole pairs. Similarly, a solid/liquid junction is formed between the semiconductor and the electrolyte in a PEC photodetector. The apparent rectification characteristics of the dark current indicate that the energy bands bend at the α-Ga2O3 nanorods/electrolyte interface. The local electric field in the semiconductor effectively promotes the separation of carriers. The photodetectors exhibit a high light/dark current ratio (Ilight/Idark) of 68.7; fast rise and decay response times of 0.1 and 0.06 s, respectively; and a high responsivity of 11.2 mA/W (@230 nm) at zero bias. The wire-shaped photoanode is beneficial for realizing potential omnidirectional solar-blind detection.

Multifunctional indium selenide devices based on van der Waals contacts: High-quality Schottky diodes and optoelectronic memories

Van der Waals semiconductors, with ultrathin body thickness and dangling-bond-free surfaces, have been employed to fabricate a vast range of electronic and optoelectronic devices such as transistors, photodiodes and memories. The integration of these different functional elements into one single device, usually referred to as multifunctional device, has received great research attention in the recent years. In this work, we realized a multifunctional device, based on the van der Waals semiconductor Indium Selenide (InSe), which can work both as a high-quality Schottky diode with current rectification and photovoltaic characteristics and as a memory. By exploiting the all-dry deterministic transfer fabrication method, we deposited the 2D InSe channel onto pre-deposited graphite and platinum electrodes, whose theoretical work functions differ of ∼1.0–1.4 eV. Thanks to a controllable InSe air passivation treatment, these devices, which start in a non-rectifying state with negligible electrodes-InSe barriers, gradually evolve into Schottky diodes, presenting a final sizeable Schottky barrier height of 556 ± 50 meV at the Pt-InSe interface, thus resulting in a gradual tuning of the device photoresponsivity and photovoltaic parameters (such as the open circuit voltage Voc). The multifunctional capabilities of these devices were demonstrated by using them as optoelectronic memories, which can achieve on-off ratios between the logical ‘1’ and ‘0’ up to 100 and retention times of thousands of seconds. This multifunctional behavior can be ascribed to the traps present in the system, which on one side influences the metal-semiconductor barriers and on the other introduces charge storage capabilities at the base of the memory operation. Our results demonstrate that trap state modulation can be an important tuning knob for thin InSe in the field of electronics and optoelectronics.

Charge transmission of MoS<sub>2</sub>/MoTe<sub>2</sub> vertical heterojunction and its modulation

The heterojunction device based on two-dimensional materials possesses unique photoelectric properties due to its nanoscale thickness and van der Waals (vdWs) contact surface. In this paper, a gate-voltage-tunable MoS<sub>2</sub>/MoTe<sub>2</sub> vertical vdWs heterojunction device is constructed. The Kelvin probe force microscopy (KPFM) technology is combined with the electric transport measurement technology, thereby revealing the charge transport behavior of the MoS<sub>2</sub>/MoTe<sub>2</sub> heterojunction under dark condition and laser-irradition condition, including the bipolarity characteristics of the transition from n-n<sup>+</sup> junction to p-n junction. In this paper, the charge transport mechanism of heterojunction is explained comprehensively and systematically, including the charge transmission process of n-n<sup>+</sup> junction and p-n junction under positive and negative bias conditions, the transformation of nodule behavior with gate voltage, the influence of barriers on charge transmission, the different rectification characteristics between n-n<sup>+</sup> junction and p-n junction, the major role of source and leakage bias voltage in band tunneling, and the influence of photogenerated carriers on electrical transmission. The method in this work can be generalized to other two-dimensional heterojunction systems and also provide an important reference for improving the performance of two-dimensional semiconductor devices and their applications in the future.

Preparation of CuO films at different sputtering powers and the effect of operating temperatures on the photovoltaic characteristics of p-CuO/n-Si heterojunction

With the progressively prominent impact of pollution caused by the extensive use of unsustainable fossil energy on the environment, clean energy with solar energy as an important component is developing rapidly. As a p-type semiconductor material with excellent performance, CuO is expected to become one of the most competitive photovoltaic materials in the field of optoelectronic devices. We first explored the effects of changing the sputtering power on the crystalline quality of CuO thin films, and systematically investigated the crystal structure, surface morphology, optical and electrical properties. Then we fabricated an Au/p-CuO/n-Si/Al heterojunction solar cell by magnetron sputtering and analyzed the influence of the device on the electrical properties at different temperatures. High rectification characteristics typical of diodes were obtained. Finally, by measuring and calculating the photovoltaic performance of the device under simulated sunlight irradiation, we studied the dependence of the device operating temperature on the photoelectric conversion efficiency in detail.

Pt/ZnGa₂O₄ Schottky Barrier Diodes Fabricated by Using Single Crystal n-ZnGa₂O₄ (111) Substrates

In this letter, we fabricated Schottky barrier diodes (SBDs) using n-type zinc gallium oxide (n-ZnGa2O4) single-crystal substrates, which were grown from the melt by the vertical gradient freeze (VGF) method. X-ray diffraction rocking curve and Laue diffraction results indicate the good crystal quality. The electrical properties of SBDs fabricated on substrates with two doping concentrations are systematically investigated. Heavily-doped (HD) SBDs exhibit lower differential specific on-resistance (~1.13 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2) and lower turn-on voltage (~0.16 V) while the lightly-doped (LD) SBDs exhibit better ideality factor (1.17), rectification characteristics (on/off ratio ~1011) and lower reverse leakage. In addition, we separately tested the electrical properties of the two devices at different temperatures (298 K-473 K). The results of varying temperature show that LD-SBDs have better temperature stability in smaller variation of ideality factor and barrier height with temperature. Based on these experimental results, this work demonstrates the great promise of ZnGa2O4 materials to fabricate high-performance power devices.

Photoluminescence and Electrical Properties of n-Ce-Doped ZnO Nanoleaf/p-Diamond Heterojunction.

The n-type Ce:ZnO (NL) grown using a hydrothermal method was deposited on a p-type boron-doped nanoleaf diamond (BDD) film to fabricate an n-Ce:ZnO NL/p-BDD heterojunction. It shows a significant enhancement in photoluminescence (PL) intensity and a more pronounced blue shift of the UV emission peak (from 385 nm to 365 nm) compared with the undoped heterojunction (n-ZnO/p-BDD). The prepared heterojunction devices demonstrate good thermal stability and excellent rectification characteristics at different temperatures. As the temperature increases, the turn-on voltage and ideal factor (n) of the device gradually decrease. The electronic transport behaviors depending on temperature of the heterojunction at different bias voltages are discussed using an equilibrium band diagram and semiconductor theoretical model.

Interface Influence on the Photoelectric Performance of Transition Metal Dichalcogenide Lateral Heterojunctions.

The ultrathin feature of two-dimensional (2D) transition metal dichalcogenides (TMDs) has brought special performance in electronic and optoelectronic fields. When vertical and lateral heterojunctions are made using different TMD combinations, the original properties of premier TMDs can be optimized. Especially for lateral heterojunctions, their sharp interface signifies a narrow space charge region, leading to a strong in-plane built-in electric field, which may contribute to high separation efficiency of photogenerated carriers, good rectification behavior, self-powered photoelectric device construction, etc. However, due to the poor controllability over the synthesis process, obtaining a clean and sharp interface of the lateral heterojunction is still a challenge. Herein, we propose a simple chemical vapor deposition (CVD) method, which can effectively separate the growth process of different TMDs, thus resulting in good regulation of the composition change at the junction region. By this method, MoS2-WS2 lateral heterojunctions with sharp interfaces have been obtained with good rectification characteristics, ∼105 on/off ratio, 1874% external quantum efficiency, and ∼120 ms photoresponse speed, exhibiting a better photoelectric performance than that of the lateral ones with graded junctions.

Room-Temperature Fabrication of p-Type SnO Semiconductors Using Ion-Beam-Assisted Deposition.

Over the past decade, SnO has been considered a promising p-type oxide semiconductor. However, achieving high mobility in the fabrication of p-type SnO films is still highly dependent on the post-annealing procedure, which is often used to make SnO, due to its metastable nature, readily convertible to SnO2 and/or intermediate phases. This paper demonstrates a fully room-temperature fabrication of p-type SnOx thin films using ion-beam-assisted deposition. This technique offers independent control between ion density, via the ion-gun anode current and oxygen flow rate, and ion energy, via the ion-gun anode voltage, thus being able to optimize the optical band gap and the hole mobility of the SnO films to reach 2.70 eV and 7.89 cm2 V-1 s-1, respectively, without the need for annealing. Remarkably, this is the highest mobility reported for p-type SnO films whose fabrication was carried out entirely at room temperature. Using first-principles calculations, we rationalize that the high mobility is associated with the fine-tuning of the Sn-rich-related defects and lattice densification, obtained by controlling the density and energy of the oxygen ions, both of which optimize the spatial overlap of the valence bands to form a continuous conduction path for the holes. Moreover, due to the absence of the annealing process, the Raman spectra reveal no significant signatures of microcrystal formation in the films. This behavior contrasts with the case involving the air-annealing procedure, where a complex interaction occurs between the formation of SnO microcrystals and the formation of SnOx intermediate phases. This interplay results in variations in grain texture within the film, leading to a lower optimum Hall mobility of only 5.17 cm2 V-1 s-1. Finally, we demonstrate the rectification characteristics of all-fabricated-at-room-temperature SnOx-based p-n devices to confirm the viability of the p-type SnOx films.

Preparation of novel B4C nanostructure/Si photodetectors by laser ablation in liquid

In this study, boron carbide (B4C) nanoparticles (NPs) are synthesized by pulsed laser ablation of boron in ethanol at a laser fluence of 6.36 J cm−2 pulse−1. The effect of numbers of laser pulses on the structural, optical, and electrical properties of B4C NPs was studied. X-ray diffraction (XRD) results revealed that all B4C nanoparticles synthesized were polycrystalline in nature with a rhombohedral structure. When the laser pulses increased from 500 to 1500, the optical band gap of B4C decreased from 2.45 to 2.38 eV. Fluorescence measurements showed the emission of two emission peaks. The Raman spectra of B4C nanoparticles exhibit six vibration modes centered at 270, 480, 533, 722, 820, and 1080 cm−1. Field emission scanning electron microscope (FESEM) images show the formation of spherical nanoparticles of an average size of 68, 75, and 84 nm for samples prepared at 500, 1000, and 1500 pulses, respectively. The dark I–V characteristics of B4C/Si heterojunction photodetectors showed rectification characteristics, and the heterojunction prepared at 500 pulses exhibits the best junction characteristics. The illuminated I–V characteristics of B4C/p-Si heterojunction photodetectors exhibited high photosensitivity to white light. The spectral responsivity of the p-B4C/p-Si photodetector shows that the maximum responsivity was 0.66 A W−1 at 500 nm for a photodetector prepared at 500 pulses. The highest specific detectivity and quantum efficiency were 2.18 × 1012 Jones and 1.64 × 102% at 550 nm, respectively, for a heterojunction photodetector fabricated at 500 pulses, The ON/OFF ratio, rise time, and fall time are measured as a function of the number of laser pulses. The photodetector fabricated at 1500 laser pulses showed roughly rise and fall intervals of 1.5 and 0.8 s, respectively.

The Mechanism of Performance Variations in MoS2 Vertical Schottky Metal–Semiconductor Photodiode Based on Thermionic Emission Theory

Atomically thin 2-D semiconductors are widely used to build various novel photodiodes due to their appropriate band structure and dangling-bond-free surface. These emerging 2-D photodiodes have shown excellent performance, especially in responsivity. Here, we report a Schottky metal–semiconductor photodiode with an ultrashort molybdenum disulfide (MoS2) channel constructed by a vertical structure. The device showed excellent rectification and optical response characteristics due to the large Schottky barrier height ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{q}\varphi _{\text{SB}}$ </tex-math></inline-formula> ) through the physical transfer method to get rid of the Fermi-level pinning effect. In addition, the vertical structure dramatically reduces the channel length to the atomic scale and efficiently collects excited carriers with little recombination loss. Furthermore, the responsivity in those photodiodes is often associated with the light intensity and voltage bias. The thermionic emission theory was employed to explain the impacts of light intensity and voltage bias on the photodiode responsivity. This work can not only improve our fundamental understanding of the photovoltaic and photoconductive effects of 2-D semiconductors but also serve as an important reference for comparing and analyzing photodetectors based on 2-D semiconductors.

Vertical MoSe2–WSe2 p-n Heterojunctions Grown by One-Pot Chemical Vapor Deposition for Ultrafast Photodetection

Two-dimensional transition metal dichalcogenides (TMDCs) have been extensively studied in the last decade due to their atomic thin structure and unique optoelectronic properties. In particular, lateral and vertical van der Waals heterostructures by combining different transition metal dichalcogenides (TMDCs) have been studied to develop the potential applications of two-dimensional materials. However, the optical properties are challenging due to the limited quality of TMDCs based heterojunctions. In this work, vertical MoSe2/WSe2 p–n heterojunctions have been synthesized by one-pot chemical vapor deposition (CVD) method. The MoSe2 -WSe2 heterostructure exhibits rectification characteristics of a p-n junction with the rectification ratio of 100 at ±10V bias. The phototransistor based on MoSe2/WSe2 p-n heterojunction shows a photoresponse of visible(638nm). The responsivity can reach up to 20 A/W, and the detectivity is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.5\times 10^{13}$ </tex-math></inline-formula> Jones. Most importantly, the optical response time of the MoSe2/WSe2 p-n heterojunction is as fast as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$28 ~\mu $ </tex-math></inline-formula> s. The results indicate that vertical MoSe2/WSe2 p-n heterojunction could be a prospective candidate for high-performance optoelectronic devices.

Applications of quantum dot membrane electrolytes in LT-SOFCs

CeO2 existed in the form of quantum dots were used in fuel cell electrolytes for the first time after being compounded with semiconductor TiO2. The TiO2 @xCeO2 (x = 1,2,3) was evaluated as the membrane electrolyte for the semiconductor-ions membrane electrolyte fuel cells using H2 as fuels. The maximum power density of the TiO2 @ 2CeO2 quantum dot electrolyte at 550 °C reaches 839 mW cm−2, and the ion conductivity reaches 0.11 S cm−1, which is higher than the physically mixed TiO2/CeO2 composite under the same operating environment. The energy band structure and rectification characteristics test show that the cell based on TiO2/CeO2 electrolyte membrane has a physical junction effect, which can prevent electrons from passing through the interior and effectively avoid short-circuit problems. This study shows that the TiO2 @xCeO2 (x = 1,2,3) composite in quantum dots form is a promising electrolyte that can promote the development of low-temperature solid oxide fuel cell.