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- 2018
- Covalent compounds
- AlN
- Interface densification
- non-stoichiometric TiNx
- Materials Science and Engineering
- Wuhan Polytechnic University
- Yanshan University
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Stable Sn/Pb-Based Perovskite Solar Cells with a Coherent 2D/3D Interface
摘要： Low-band-gap metal halide perovskite semiconductor based on mixed Sn/Pb is a key component to realize high-ef?ciency tandem perovskite solar cells. However, the mixed perovskites are unstable in air due to the oxidation of Sn2+. To overcome the stability problem, we introduced N-(3-aminopropyl)-2-pyrrolidinone into the CH3NH3Sn0.5Pb0.5IxCl3-x thin ?lm. The carbonyl group on the molecule interacts with Sn2+/Pb2+ by Lewis acid coordination, forming vertically oriented 2D layered perovskite. The 2D phase is seamlessly connected to the bulk perovskite crystal, with a lattice coherently extending across the two phases. Based on this 2D/3D hybrid structure, we assembled low-band-gap Sn-based perovskite solar cells with power conversion ef?ciency greater than 12%. The best device was among the most stable Sn-based organic-inorganic hybrid perovskite solar cells to date, keeping 90% of its initial performance at ambient condition without encapsulation, and more than 70% under continuous illumination in an N2-?lled glovebox for over 1 month.
关键词： power conversion efficiency,2D/3D interface,stability,Sn/Pb-based,perovskite solar cells
更新于2025-11-21 11:18:25
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Laser welding characteristics of Ti-Pb dissimilar couples and element diffusion in the molten pool
摘要： Laser welding lead metal to titanium or titanium alloy, which is a typical dissimilar welding process, have a great challenge. Couples of Ti-Pb, Ti6Al4V-Pb were welded by a 3kW continuous wave Nd:YAG laser. The influences of process parameters such as laser power and laser beam offset on welding depth were investigated. Microstructure, element distribution and micro-hardness of the welds were tested. The element diffusion characteristics during laser welding of Ti-Pb couple and Ti6Al4V-Pb couple were studied based on the experiments data. Experimental results show laser beam offset is a primary factor for welding titanium alloy and lead metal, and laser power plays a critical role for welding pure titanium and lead metal. A chemical potential calculation model of Ti-Pb-Al ternary alloy was established. The calculation results show that chemical potential of Ti element increases with enhancing Pb content in Ti-Pb-Al ternary system, however, the chemical potential of Ti element decreases with increasing Pb content in Ti-Pb binary system. According to the calculation results, for Ti-Pb-Al ternary system, because of the Al element in the molten pool, the Ti element tends to diffuse into the Al element, and the diffusion driving force of Ti element to the Pb element is weak. Compared with the Ti-Pb binary system and the Ti-Pb-Al ternary system, it is more likely to form a mixed fusion weld for the binary system, and the mass transfer interface phenomenon is more serious for the ternary system, which is consistent with EDS line scan and microhardness testing results.
关键词： Chemical potential,Interface,Microstructure,Lead metal,Titanium alloy,Laser dissimilar welding
更新于2025-11-21 11:18:25
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Solvent Effects on the Interface and Film Integrity of Solution-Processed ZnO Electron Transfer Layers for Quantum Dot Light Emitting Diodes
摘要： Solution-processed ZnO nanoparticle thin film is widely used as the electron transport layers (ETLs) in quantum dot light emitting diodes (QLEDs). While the ZnO nanoparticles (NPs) synthesis process has been thoroughly optimized, very few studies have focused on exploring how the solvents for dispersing the NPs affect the film-forming process, which has profound effects on the film quality and functionality as ETLs. Herein, we present a comprehensive investigation on the impact of the dispersing agent on the materials and carrier transport properties of spin-coated ZnO NP thin films. The first four members of the alkanol family, which show considerably different viscosities and volatilities, were used in this study. ZnO NP thin films deposited with different alcohols were used as the ETLs of the QLED structure and the optoelectronic performances of the devices are compared. Alcohols with high viscosity are found to cause NP agglomerations which roughen the film surface and lead to significant leakage current. Nano-cracks in the ZnO NP film are observed when a highly volatile solvent is used due to the vigorous bursts of vapor during solvent evaporation. Our results show that proper solvent can improve the surface roughness and compactness of the solution-processed ZnO films and lead to a 30% difference in the current efficiency of QLEDs. The findings here clearly indicate the important roles of the dispersing agent in the formation of high-quality NP-based thin films, which can be an important guidance for achieving high performances in QLEDs as well as a variety of solution-based devices.
关键词： Interface,Solvent,QLEDs,Electron transport layer,ZnO
更新于2025-11-21 11:01:37
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g-C3N4 nanosheets functionalized silicon nanowires hybrid photocathode for efficient visible light induced photoelectrochemical water reduction
摘要： We report the fabrication of hybrid Si nanowires @ g-C3N4 nanosheets based photocathode using metal assisted chemical etching and facile liquid exfoliated process. The g-C3N4 nanosheets on Si nanowires form hybrid heterojunction photocathode, which exhibits an enhanced photon induced water reduction activity enabling higher photocurrent density of 22 mA cm?2 with applied bias photocurrent conversion efficiency of 4.3% under visible light irradiation. The onset potential of cathodic photocurrent is positively shifted from 41 to 420 mV vs. RHE with the short circuit current density, Jsc of 0.50 mA cm?2 owing to superior charge transport in hybrid photocathode as compared to pristine Si nanowires for hydrogen evolving reaction at pH～7. The electrochemical impedance spectroscopy measurement elucidates the interface layer of g-C3N4 nanosheets form hybrid heterojunction with Si nanowires that result significant increment in solar water reduction activity owing to low charge transferred resistance with high life time of excited electrons in conduction band. This strategy may open to design a new low cost stable hybrid heterostructure photocathode for solar induced water reduction.
关键词： Solar water reduction,Si nanowires,Photocathode,g-C3N4 nanosheets,Interface
更新于2025-11-21 11:01:37
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UV-ozone induced surface passivation to enhance the performance of Cu2ZnSnS4 solar cells
摘要： Interface property has been considered one of the most critical factors affecting the performance of semiconductor devices. In this work, we demonstrate an efficient surface passivation for the interface between Cu2ZnSnS4 (CZTS) and CdS buffer layer by using UV-ozone treatment at room temperature. The passivation led to a significant enhancement of short circuit current density (Jsc) of the device from 11.70 mA/cm2 to 18.34 mA/cm2 and thus efficiency of the CZTS solar cells from 3.18% to 5.55%. The study of surface chemistry has revealed that the UV-ozone exposure led to formation of a Sn–O rich surface on CZTS, which passivates the dangling bonds and forms an ultra-thin energy barrier layer at the interface of CZTS/CdS. The barrier is considered to be responsible for the reduction of non-radiative recombination loss in the solar cells as confirmed by photoluminescence (PL) measurement. The elongated lifetime of minority carriers in the CZTS solar cells by time-resolved PL has further verified the interface passivation effect induced by UV-ozone treatment. This work provides a fast, simple yet very effective approach for surface passivation of CZTS film to boost the performance of CZTS solar cells.
关键词： CZTS solar cell,UV-Ozone treatment,Interface modification,Surface passivation
更新于2025-11-21 11:01:37
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A systematic approach to ZnO nanoparticle-assisted electron transport bilayer for high efficiency and stable perovskite solar cells
摘要： Minimizing the interface loss of perovskite solar cells is critical to achieving high photovoltaic performance, and intensive research is underway on interfacial engineering in this regard. In this work, we introduce a ZnO nanoparticles (ZnO NPs) interlayer between phenyl-C61-butyric acid methyl ester (PCBM) and a metal electrode in order to reduce the interface loss due to charge recombination and device degradation, and also investigate the dependence of device performance on the thickness and morphology of the PCBM and PCBM/ZnO electron transport bilayer. After achieving optimized PCBM and ZnO thickness, the PCBM/ZnO bilayer-based devices reached an average power conversion efficiency of 15.63% (Max. 16.39%) with an open circuit voltage of 1.05 V, short circuit current density of 18.69 mA cm-2, and fill factor of 79.95%. In addition, hysteresis behavior and atmospheric stability are significantly improved by the incorporation of a PCBM/ZnO bilayer. Therefore, the implementation of a PCBM/ZnO electron transport bilayer is a promising approach toward achieving a high-efficiency PSC with stable power output (low J-V hysteresis) and durability.
关键词： ZnO nanoparticles,interfacial engineering,stable perovskite solar cells,interface loss,high-efficiency perovskite solar cells,electron transport bilayer
更新于2025-11-19 16:46:39
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Electrical characterization of high k-dielectrics for 4H-SiC MIS devices
摘要： We report promising results regarding the possible use of AlN or Al2O3 as a gate dielectric in 4H-SiC MISFETs. The crystalline AlN ?lms are grown by hot wall metal organic chemical vapor deposition (MOCVD) at 1100 °C. The amorphous Al2O3 ?lms are grown by repeated deposition and subsequent low temperature (200 °C) oxidation of thin Al layers using a hot plate. Our investigation shows a very low density of interface traps at the AlN/4H-SiC and the Al2O3/4H-SiC interface estimated from capacitance-voltage (CV) analysis of MIS capacitors. Current-voltage (IV) analysis shows that the breakdown electric ?eld across the AlN or Al2O3 is ～ 3 MV/cm or ～ 5 MV/cm respectively. By depositing an additional SiO2 layer by plasma enhanced chemical vapor deposition at 300 °C on top of the AlN or Al2O3 layers, it is possible to increase the breakdown voltage of the MIS capacitors signi?cantly without having pronounced impact on the quality of the AlN/SiC or Al2O3/SiC interfaces.
关键词： MIS structure,Interface traps,Al2O3/4H-SiC interface,AlN/4H-SiC interface
更新于2025-11-14 17:28:48
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Photovoltaic Properties and Series Resistance of <i>p</i> -Type Si/Intrinsic Si/ <i>n</i> -Type Nanocrystalline FeSi <sub/>2</sub> Heterojunctions Created by Utilizing Facing-Targets Direct-Current Sputtering
摘要： p-Type Si/intrinsic Si/n-type nanocrystalline iron disilicide heterojunctions were created by utilizing facing targets direct-current sputtering at the pressure of 1.33 × 10?1 Pa that investigated the photovoltaic properties. They exhibited a large leakage current and a small energy conversion ef?ciency of 0.62%. From using the method of Nicollian and Brews, the series resistance (Rs) values at zero bias voltage were 7.40 Ω at 2 MHz and 7.57 Ω at 50 kHz, respectively, which were in agreement with that estimated by the means of Norde. From applying the method of Hill-Coleman, the interface state density (Nss) values were 3.15 × 1015 cm?2 eV?1 at 50 kHz and 8.93 × 1013 cm?2 eV?1 at 2 MHz. The obtained results revealed the presence of Rs and Nss at the junction interface, which should be the potential cause of spoiled photovoltaic performance in the heterojunctions.
关键词： Heterojunctions,Facing-Targets Direct-Current Sputtering,Nanocrystalline Iron Disilicide,Series Resistance,Interface State Density
更新于2025-11-14 17:28:48
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<i>C–V–f, G–V–f</i> and <i>Z″–Z′</i> Characteristics of <i>n</i> -Type Si/B-Doped <i>p</i> -Type Ultrananocrystalline Diamond Heterojunctions Formed via Pulsed Laser Deposition
摘要： n-Type Si/p-type B-doped ultrananocrystalline diamond heterojunction photodiodes were built using pulsed laser deposition at a heated substrate temperature of 550 °C. Following the capacitance–voltage–frequency (C–V–f) and conductance–voltage–frequency (G–V–f) plots, the series resistance (Rs) values at zero bias voltage were 154.41 Ω at 2 MHz and 1.72 kΩ at 40 kHz. Rs should be ascribed to Rs occurring in the metallic contact and the bulk resistance in the active layer. At 40 kHz, the interface state density (Nss) was 1.78 × 10^13 eV^?1 cm^?2 and dropped exponentially to 1.39 × 10^12 eV^?1 cm^?2 at 2 MHz. An assessed Nss occurring at the heterojunction interface was the cause of deterioration in the photo-detection properties. At different V values, the appearance of the real (Z') and imaginary (Z'') characteristic curves revealed single semicircles whose centers lay below the Z' axis. The magnitude of the curve was diminished with the increment of V. The particularities of Z''–Z' plots can be identified as an equivalent circuit model. The appropriate model included Rs, which was combined with the parallel circuit of resistance and constant phase element.
关键词： UNCD,Interface State Density,Series Resistance,PLD,Impedance
更新于2025-11-14 17:28:48
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[IEEE 2017 IEEE 44th Photovoltaic Specialists Conference (PVSC) - Washington, DC (2017.6.25-2017.6.30)] 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC) - Interface Effects of Alkali Treatment on Cu-Rich Thin Film Solar Cells
摘要： CuInSe2 absorbers grown under Cu-excess have better current collection compared to those grown as Cu-poor. However, cells based on Cu-excess absorbers show lower efficiency due to a worse absorber-buffer interface where the interface recombination is the dominant recombination path. In this paper, potassium fluoride post-deposition treatment is used to improve this interface, as evidenced by an activation energy of the main recombination path close to the band gap energy. The treatment also succeeded in eliminating the 200-meV step observed in admittance measurements; a main characteristic of Cu-excess CuInSe2 cells.
关键词： admittance measurements,Cu-excess,interface recombination,potassium fluoride post-deposition treatment,CuInSe2
更新于2025-11-14 17:28:48