- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhanced Stability of Perovskite Solar Cells Incorporating Dopant‐Free Crystalline Spiro‐OMeTAD Layers by Vacuum Sublimation
摘要： The main handicap still hindering the eventual exploitation of organometal halide perovskite-based solar cells is their poor stability under prolonged illumination, ambient conditions, and increased temperatures. This article shows for the first time the vacuum processing of the most widely used solid-state hole conductor (SSHC), i.e., the Spiro-OMeTAD [2,2′,7,7′-tetrakis (N,N-di-p-methoxyphenyl-amine) 9,9′-spirobifluorene], and how its dopant-free crystalline formation unprecedently improves perovskite solar cell (PSC) stability under continuous illumination by about two orders of magnitude with respect to the solution-processed reference and after annealing in air up to 200 °C. It is demonstrated that the control over the temperature of the samples during the vacuum deposition enhances the crystallinity of the SSHC, obtaining a preferential orientation along the π–π stacking direction. These results may represent a milestone toward the full vacuum processing of hybrid organic halide PSCs as well as light-emitting diodes, with promising impacts on the development of durable devices. The microstructure, purity, and crystallinity of the vacuum sublimated Spiro-OMeTAD layers are fully elucidated by applying an unparalleled set of complementary characterization techniques, including scanning electron microscopy, X-ray diffraction, grazing-incidence small-angle X-ray scattering and grazing-incidence wide-angle X-ray scattering, X-ray photoelectron spectroscopy, and Rutherford backscattering spectroscopy.
关键词： perovskite solar cells,organometal halide perovskites,stability,vacuum deposition,solid state hole conductors,Spiro-OMeTAD
更新于2025-09-11 14:15:04
-
Influence of Work Function of Carrier Transport Materials with Perovskite on Switchable Photovoltaic Phenomena
摘要： The hysteresis effect and switchable photovoltaic phenomena in organo-metal halide perovskite have been observed in perovskite solar cells with certain structures and under certain measure conditions. These phenomena were favorably applied to resistive random-access memory and human-brain-mimicking devices, especially using photons as a reading or stress probe apart from using electrical probe. However, the mechanisms causing these effects are not fully understood. In this paper, the perovskite devices with different hole transporting layers, which have the work functions ranging from 5.9 eV to 3.7 eV, were fabricated and systematically characterized by current-voltage measurements and time-resolved photo-response measurements. These measurements show that the switchable photovoltaic phenomena are highly related to the work function of the hole transporting layer. The interfacial electronic structures of perovskite and several materials were studied in details using X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), suggesting that the switchable photovoltaic is extensively dependent on the strong band bending effect. Light-mediated XPS measurements reveals that the degree of band bending in the perovskite layer was manipulated by charge trapping/de-trapping and hole-carrier accumulation. Based on the electrical measurements and band diagram, we propose a model that combines ion migration and charge trapping/detrapping processes to explain the switchable photovoltaic phenomena.
关键词： work function,band bending,hole transporting layer,perovskite,ion migration,charge trapping,switchable photovoltaic
更新于2025-09-11 14:15:04
-
A Molecular Design Strategy in Developing Titanyl Phthalocyanines as Dopant-Free Hole Transporting Materials for Perovskite Solar Cells: Peripheral or Non-Peripheral Substituents?
摘要： We demonstrate a molecular design strategy to enhance the efficiency of phthalocyanine (Pc) based hole transporting materials (HTMs) in perovskite solar cells (PSCs). Herein, two titanyl phthalocyanine (TiOPc) derivatives are designed and applied as dopant-free HTMs in planar n-i-p structured PSCs. The newly developed TiOPc compounds possess eight n-hexylthio groups attached to either peripheral (P-SC6-TiOPc) or non-peripheral (NP-SC6-TiOPc) positions of the Pc ring. Utilizing these dopant-free HTMs in PSCs with a mixed cation perovskite as the light absorbing material and tin oxide (SnO2) as the electron transporting material (ETM) results in a considerably enhanced efficiency for NP-SC6-TiOPc based devices compared to PSCs using P-SC6-TiOPc. Hence, all the photovoltaic parameters, including power conversion efficiency (PCE), fill factor, open circuit voltage and short-circuit current density are remarkably improved from 5.33 ± 1.01%, 33.34 ± 3.45%, 0.92 ± 0.18 V, and 17.33 ± 2.08 mA cm-2 to 15.83 ± 0.44%, 69.03 ± 1.59%, 1.05 ± 0.01 V, and 21.80 ± 0.36 mA cm-2, respectively, when using the non-peripheral substituted TiOPc derivative as the HTM in a PSC. Experimental and computational analysis suggests more compact molecular packing for NP-SC6-TiOPc than P-SC6-TiOPc in the solid state due to stronger π-π interactions, leading to thin films with better quality and higher performance in hole extraction and transportation. PSCs with NP-SC6-TiOPc also offer much higher long-term stability than P-SC6-TiOPc based devices, under ambient conditions with a relative humidity of 75%.
关键词： non-peripheral substituents,titanyl phthalocyanines,perovskite solar cells,power conversion efficiency,hole transporting materials
更新于2025-09-11 14:15:04
-
Spherical photon orbits in the field of Kerr naked singularities
摘要： For the Kerr naked singularity (KNS) space-times, we study properties of spherical photon orbits (SPOs) con?ned to constant Boyer-Lindquist radius r . Some new features of the SPOs are found, having no counterparts in the Kerr black hole (KBH) spacetimes, especially stable orbits that could be pure prograde/retrograde, or with turning point in the azimuthal direction. At r > 1 (r < 1) the covariant photon energy E > 0 (E < 0), at r = 1 there is E = 0. All unstable orbits must have E > 0. It is shown that the polar SPOs can exist only in the spacetimes with dimensionless spin a < 1.7996. Existence of closed SPOs with vanishing total change of the azimuth is demonstrated. Classi?cation of the KNS and KBH spacetimes in dependence on their dimensionless spin a is proposed, considering the properties of the SPOs. For selected types of the KNS spacetimes, typical SPOs are constructed, including the closed paths. It is shown that the stable SPOs intersect the equatorial plane in a region of stable circular orbits of test particles, depending on the spin a. Relevance of this intersection for the Keplerian accretion discs is outlined and observational effects are estimated.
关键词： Keplerian accretion discs,Kerr black hole,dimensionless spin,stable orbits,covariant photon energy,observational effects,closed SPOs,spherical photon orbits,azimuthal direction,Kerr naked singularity
更新于2025-09-11 14:15:04
-
Three-dimensional classical imaging of a pattern localized in a phase space
摘要： In most imaging experiments, the structure of an object is defined in a position space. Such a structural pattern can be stationary, or for a dynamic object it can be nonstationary with time. An image of such an optically responsive object can be produced with a lens, therefore such an object can be seen with a camera or by the human eye. In this paper, we go beyond the conventional notion of imaging. A structural pattern of objects in our experiment is defined in a phase space, therefore such a pattern cannot be imaged with a lens or a camera, and the human eye cannot visualize it. A pattern in phase space is produced from object transparencies and imprinted onto the phase space of an atomic gaseous medium of a Doppler-broadened absorption profile at room temperature by utilizing velocity-selective hole burning in the absorption profile. The pattern is localized in a unique three-dimensional phase space, which is a subspace of the six-dimensional phase space. Tomographic images of the localized phase-space pattern are captured at different momentum locations by a laser light that has never interacted with actual objects. In addition, imaging of an imprinted phase-space pattern of an object of nonuniform transmittance is presented.
关键词： imaging,tomographic imaging,phase space,Doppler-broadened absorption profile,velocity-selective hole burning
更新于2025-09-10 09:29:36
-
Generation of hole gas in non-inverted InAl(Ga)N/GaN heterostructures
摘要： InAlN/GaN structures are grown using organometallic chemical vapor deposition at 730 °C. The sample for which the chamber cleaning step was applied after GaN growth shows a sharp In0.3Al0.7N/GaN transition, free electron density of ～2 × 1011 cm?2 and mobility of 44 cm2 V?1 s?1. On the other hand, the sample prepared without growth interruption demonstrated In0.4Al0.15Ga0.45N at the interface and compositional grading towards the In0.4Al0.6N surface. In this case a two-dimensional hole gas (2DHG) is created with a density of ～2 × 1012 cm?2 and mobility of ～0.6 cm2 V?1 s?1. Ga incorporation in the InAlN barrier is crucial for designing non-inverted 2DHG transistors.
关键词： InAlN/GaN,non-inverted heterostructures,two-dimensional hole gas,organometallic chemical vapor deposition
更新于2025-09-10 09:29:36
-
Charging of electron beam irradiated amorphous carbon thin films at liquid nitrogen temperature
摘要： We studied the charging behavior of an amorphous carbon thin film kept at liquid-nitrogen temperature under focused electron-beam irradiation. Negative charging of the thin film is observed. The charging is attributed to a local change in the work function of the thin film induced by electron-stimulated desorption similar to the working principle of the hole free phase plate in its Volta potential implementation at elevated temperature. The negative bias of the irradiated film arises from the electron beam induced desorption of water molecules from the carbon film surface. The lack of positive charging, which is expected for non-conductive materials, is explained by a sufficient electrical conductivity of the carbon thin film even at liquid-nitrogen temperature as proven by multi-probe scanning tunneling microscopy and spectroscopy measurements.
关键词： Thin film,Radiation damage,Phase plate,Electron-beam induced charging,Hole free phase plate,Transmission electron microscope,Volta phase plate
更新于2025-09-10 09:29:36
-
[IEEE 2018 2nd International Conference on Electronics, Materials Engineering & Nano-Technology (IEMENTech) - Kolkata (2018.5.4-2018.5.5)] 2018 2nd International Conference on Electronics, Materials Engineering & Nano-Technology (IEMENTech) - Design and Simulation of 8-cavity hole-slot type magnetron in CST
摘要： In this study, the design and simulation of 8-cavity hole-slot type magnetron using the electromagnetic CST software has been presented. A magnetron simulation on CST particle studio represents three configurations like as Eigen-mode, Particle Tracking and Particle in Cell (PIC) Simulation. The first simulation ensures the mode excitation whereas remaining two simulations are required for the desired operation of magnetron. Here, the mathematical calculation of the 8-resonator system is compared with the simulation results to verify the accuracy of the theoretical results. In this paper, magnetron has been designed for X band where the impact of electric field with respect to frequency and time for PIC solver is investigated and found peak at 10GHz.
关键词： X-band,Particle studio,Hole-slot,Magnetron
更新于2025-09-10 09:29:36
-
[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Closed-Form Solution of Simultaneous Denoising and Hole Filling of Depth Image
摘要： This paper presents a novel Time-of-Flight (ToF) depth recovery algorithm minimizing a new quadratic energy function utilizing depth and infrared data. The proposed energy function consists of a filtering term and a reconstruction term to remove noise and fill holes simultaneously in a depth image. In the filtering term, a new multilateral weight is introduced by fully using available spatial, depth, and infrared information. In the reconstruction term, a Poisson equation for reconstructing a depth image from its gradients is used whereas the depth gradients inside hole regions are interpolated with the proposed infrared-guided moving least squares. The recovered depth data can be obtained by solving a sparse linear system derived from minimizing the proposed energy function. Experimental results demonstrate that the proposed algorithm provides good depth recovery performance without introducing texture copy or blur artifacts compared to the existing methods.
关键词： hole filling,inpainting,time-of-flight depth,denoising,quadratic energy function,Depth recovery
更新于2025-09-10 09:29:36
-
Implementation of Real-Time Post-Processing for High-Quality Stereo Vision
摘要： We propose a novel post-processing algorithm and architecture that simultaneously uses the passive and active stereo vision information to improve the reliability of the three-dimensional disparity in a hybrid stereo vision system. The proposed architecture consists of four steps — left-right consistency checking, semi-2D hole filling, a tiny adaptive variance checking, and a 2D weighted median filter. The experimental results show that the error rate of the proposed algorithm (5.77%) is less than that of a raw disparity (10.12%) for a real-world camera image having a 1,280 × 720 resolution and maximum disparity of 256. Moreover, for the famous Middlebury stereo image sets, the proposed algorithm’s error rate (8.30%) is also less than that of the raw disparity (13.7%). The proposed architecture is implemented on a single commercial field-programmable gate array using only 13.01% of slice resources, which achieves a rate of 60 fps for 1,280 × 720 stereo images with a disparity range of 256.
关键词： post processing,hole filling,variance check,FPGA,weighted median filter,Stereo vision,3D depth
更新于2025-09-10 09:29:36