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In this contribution, we investigate why different dopant species and back-contact architectures lead to different sub-bandgap behaviors in CdSeTe solar cells. Through extraction of the absorptance from photoluminescence spectra, we parse the contributions from material properties and from cell optics. We show that, as expected, arsenic doping leads to an increase in sub-bandgap features over traditional copper doping, and that this is a material property of arsenic-doped CdSeTe. Conversely, the increase in sub-bandgap absorption and emission using alternative back contact architectures can be attributed to the cell optics, and more specifically to the increased reflectance of the back interface, leading to at least a doubling of the pathlength for sub-bandgap photons.

MIMO array is a very effective millimeter wave imaging system which can be used for human security inspection. Due to the inconsistency between the equivalent phase center and the actual transmit-receive antenna positions, we need to calibrate the original receiving data so that we can use FFT imaging method for fast reconstruction. In this paper, a data calibration method is proposed. According to the actual MIMO array, multiple calibration reference centers are selected to calibrate the near-field data, and then the FFT method is used for fast image reconstruction. Simulation results show the effectiveness of the method.

The charging reliability of electric vehicles directly affects the owner's daily travel and charging satisfaction, while the current charging and discharging strategies for electric vehicles do not take into account the charging reliability indicators. Aiming at this quo, control method for electric vehicles based on charging reliability indicators is proposed in this paper. The method puts forward an indicator of electric vehicle charging reliability, and based on this indicator, combined with peak and valley time-of-use electricity prices, an orderly charging and discharging control process of electric vehicles is given. Taking IEEE RBTS-Bus6 system as an example, the method presented in this paper are simulated. The simulation verifies the effectiveness of the control strategy proposed in this paper. The results show that it performs effective in improving the reliability of EV charging and user satisfaction.

We report significant advances in understanding and reducing nonradiative Shockley-Read-Hall recombination in polycrystalline CdSe x Te 1-x , leading to microsecond charge carrier lifetimes. In undoped Al 2 O 3 -passivated heterostructures we find external radiative efficiency 0.2%, quasi-Fermi level splitting 950 mV, mobility 100 cm2/(Vs), and diffusion length 14 µm. In solar cells measured lifetimes can exceed 1 µs. We interpret this data to indicate MgZnO/CdSeTe interface recombination velocity

We report seminal advances in fabrication and understanding of group V (As) doped thin-film polycrystalline CdTe-based solar cells. The devices are fabricated using a novel approach, by sublimating layers of CdSeTe and CdSeTe:As. This new method allowed us to achieve minority carrier lifetime of over 1 µs, carrier concentration of more than 5×l015cc−1 and external radiative efficiency of over 2 % in a device configuration. We find an increase in open-circuit voltage when comparing As-doped, Cu-doped and undoped devices. The choice of CdSeTe instead of a CdTe-only absorber has been explained using first-principle density functional theory model. A SCAPS device model is used to analyze the potential causes for lower open-circuit voltage.

We applied time-resolved photoluminescence (TRPL) spectroscopy to study optimized chalcopyrite (Ag,Cu)(In,Ga)Se 2 thin films. The device shows power conversion efficiency of 18.7%. The metastable defect V Se -V Cu within ACIGS at $\text{Ev}+0.98\ \text{eV}$ is detected in sub-bandgap TRPL excitation spectra. TRPL lifetime of 50 ns is limited by the density of mid-gap defects such as Cu Ga or Cu In . The similarity of TRPL dynamics before and after light soaking indicates the optimized ACIGS thin film is less metastable because the density of V Cu -V Se defect is reduced to below 1015cm−3. This study indicates that ACIGS has improved cell efficiency and reliability characteristics.

The first step to understand the origin of losses in any photovoltaic solar cell is to determine the fundamental thermodynamic efficiency and voltage limits of such a device. In this contribution, we detail techniques to calculate the voltage limit in the case of cadmium selenium telluride (CdSeTe) solar cells, and how approaches based on bandgap alone—i.e., the Shockley-Queisser approach with step-function absorptance—can overestimate the thermodynamic open-circuit voltage limit $V_{oc,ideal}$ . This is particularly true for arsenic-doped samples, which tend to exhibit below-bandgap absorptance.

Since excellent carrier lifetimes and front interface electronic quality are now achieved, rear interface recombination can limit V OC in $\text{CdSe}_{\mathrm{x}}\text{Te}_{1-\mathrm{x}}/\text{CdTe}$ solar cells. Several back-contact structures for devices were fabricated using combinations of tellurium, aluminum oxide, amorphous silicon, and indium tin oxide (ITO). Time-resolved photoluminescence was used to characterize such structures. We show increasingly improved interface passivation through the subsequent use of aluminum oxide, amorphous silicon, and ITO. Additionally, we show that arsenic-doped absorbers form a more passive interface with numerous back contact structures.

Enargite Cu 3 AsS 4 is a promising absorber for thin-film solar cells but little is known about its optoelectronic properties. Here, we present photoluminescence (PL) spectroscopy, time-resolved terahertz spectroscopy (TRTS), timeresolved photoluminescence (TRPL) spectroscopy, and cyclic voltammetry (CV) measurements of enargite thin films. The results indicate promising defect characteristics with minority carrier lifetimes on the order of ns, and band alignments suggest that buffer layers besides CdS must be developed to achieve high efficiency Cu 3 AsS 4 solar cells.

We demonstrate the use of time-resolved terahertz spectroscopy coupled with numerical modeling of the transport equations to elucidate photoexcited carrier dynamics in a photovoltaic absorber. By measuring a high-quality CU 2 ZnSnSe 4 single crystal that exhibited device efficiency of 8.6%, we show that critical parameters including mobility, surface recombination velocity, and Shockley-Read-Hall lifetime can be obtained. Mobility values of 80 cm2/Vs were validated with Hall effect measurements. Surface recombination velocity could be reduced by at least two orders of magnitude, to $\pmb{10^{4}}\mathbf{cm}/\mathbf{s}$ , with appropriate chemical and mechanical polishing. Carrier lifetimes exceeding 10ns indicate promise for devices with high photovoltage. Terahertz spectroscopy provides complementary insight to conventional time-resolved photoluminescence and is particularly valuable for materials that are not strongly emissive.

Aiming at the problems that the implicit Runge-Kutta method is hard to programming use, and lack precision analysis of implicit Runge-Kutta methods, several classic five-stage implicit Runge-Kutta methods are used to compare their calculation accuracy and the sensitivity of calculation step. The study results provided a reference for the selection using of five-stage implicit Runge-Kutta methods.

E-commerce has rapid growth in the last two decades due to the development of information technologies, mobile network services and application of big data. Nowadays, e-commerce has reached a stage in which e-businesses are far beyond the online trading of buy-pay-deliver, but covers a much broader spectrum of line business activities, such as financing, which indicates that e-commerce has been transited from monetary transfer to credit transfer. The financial services for e-businesses have now incurred fundamental changes in credit risk management, with significant impacts on the traditional credit system, such as timeliness, service quality, cash flow and liquidity, and scalability of services, etc. In this paper, based on an online-credit scoring model, we identified important factors that improve the prediction accuracy of a credit scoring model and reduces the probability of default, which also demonstrated the important role of non-financial data in credit risk control in the e-businesses environment.

In online P2P lending market, borrowers need to make strategic decisions, which will determine they will get the loans or not. In this study, we firstly investigate what and how the decisions made by borrowers influence the auction results. The empirical results display that borrower' decisions, e.g., loan amount, interest rate will determine whether she could successfully fund loan or not, especially loan amount requested by borrowers. Then, it is focus on analyzing the difference of two borrower's critical decisions (loan amount and interest rate) among successful, unsuccessful capable and incapable listings, and find out that borrowers of three types of listings make heterogeneous decisions. Finally, we provide some suggestions to online P2P lending market about borrowers' decisions aid services based on the results, which could be a contribution with the practical implementation of borrower decision support system.

We posit that visually descriptive language offers computer vision researchers both information about the world, and information about how people describe the world. The potential benefit from this source is made more significant due to the enormous amount of language data easily available today. We present a system to automatically generate natural language descriptions from images that exploits both statistics gleaned from parsing large quantities of text data and recognition algorithms from computer vision. The system is very effective at producing relevant sentences for images. It also generates descriptions that are notably more true to the specific image content than previous work.

Based on a large volume of relevant documents on smart grid, the paper summarized current developing situation of smart grid, including the definition and character description in Europe, America and China. It pointed out that because of different development environment and drive force, different countries' power grid enterprises and organizations comprehend the smart grid concept variously. The research and practical thoughts, methods and key points were quite different. Then integrated with Chinese conditions, the paper stated the power grid current development situation and challenges. Based on the power grid construction situation in China, the authors gave out a series of suggestions on how to construct the Chinese-style smart gird. The suggestions included establishing China's smart grid development strategy as soon as possible, enhancing the ultra-high voltage main power grid and its supporting equipment construction, devoting much effort to develop new resources and related technology, etc. As the initial stage of smart grid, there is much more work remains to be carried out in the future.

In this paper, we propose an adaptive quality recommendation mechanism to help software service providers understand the dynamism of quality demand from the majority of requesters accurately. The unique feature of our approach is that based on the intra-cluster proximity index (called the icp-index) that we propose, the granularity of service clustering can be adjusted dynamically to meet the wide variation of service providers who want to target their services to different groups of clients. Experiments show that our approach is more accurate and flexible to identify the need of service quality of requesters than existing solutions such as simple averaging, minimum-maximum-mean, or traditional interval-range data clustering.

This paper presents a preliminary effort on visualization and analysis of social networks for online marketplaces. We use one of the most popular e-business models, eBay, as a case study. By extracting relevant data, we generate tree structure displays using 'Prefuse' interactive visualization toolkit, and study the social interaction among sellers and buyers, across geographical boundaries. We also illustrate how this study can improvise our understanding of online customer interaction patterns. Such an analysis could lead to possible enhancements to the current e-business models.

QoS (Quality of Service) provisioning is an important factor that determines the success of any software service deployment. Defining what level of quality a software service should publish in the registry is a big challenge because of (i) the lack of requestor's QoS requirements when a service is firstly published, (ii) the dynamic, diversified QoS requirements of SLAs (Service Level Agreement) and invocation instances to the same service provider, and (iii) the inability of requestors to precisely specify their QoS requirements for the services they demand. In this paper, we propose a mechanism to automatically recommend the QoS requirements of a given service by referencing previously signed SLAs and their associated runtime instance information of all "similar services" within a service community. Both the mathematical model and its supporting system architecture are given. This work is important because it assists service providers to improve their service quality and competitiveness in a given service community.