Search results for "photovoltaic"
showing 10 items of 646 documents
Hole transporting materials based on benzodithiophene and dithienopyrrole cores for efficient perovskite solar cells
2018
The development of highly efficient hole transporting materials (HTMs) for perovskite solar cells (PSCs) is still one of the most thrilling research subjects in the development of this emerging photovoltaic technology. Inner ring engineering of the aromatic core of new HTMs – consisting of three fused rings endowed with four triarylamine units – reveals major performance effects over the fabricated devices. In particular, substitution of the central pyrrole ring in dithienopyrrole (DTP) by a benzene ring – benzodithiophene (BDT) – allows enhancing the power conversion efficiency from 15.6% to 18.1%, in devices employing mixed-perovskite (FAPbI3)0.85(MAPbBr3)0.15 (MA: CH3NH3+, FA: NHCHNH3+) …
Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition
2015
Two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies (Vo) were identified in ZnO nanorods (NRs) grown by low cost chemical bath deposition. A transient behaviour in the photoluminescence (PL) intensity of the two Vo states was found to be sensitive to the ambient environment and to NR post-growth treatment. The largest transient was found in samples dried on a hot plate with a PL intensity decay time, in air only, of 23 and 80 s for the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV exposure exhibited a transient behaviour in full agreement with the PL transient, indicating a clear role of atmospheric O-2 on the surface defect states. A model fo…
Color Tuning and White Light by Dispersing CdSe, CdTe, and CdS in PMMA Nanocomposite Waveguides
2013
In this paper, active nanocomposite waveguides based on the dispersion of CdS, CdTe, and CdSe colloidal quantum dots (QDs) in PMMA are proposed. Their propagation properties are studied as a function of the concentration of nanoparticles in the polymer using the variable length stripe method. When the three nanostructures are dispersed in the same film, the structure is able to waveguide the three basic colors: red (CdSe), green (CdTe), and blue (CdS), it being possible to engineer any waveguided color by an appropriate choice of the filling factor of each QD in the PMMA matrix. For this purpose, it is important to take into account reabsorption effects and the Förster energy transfe…
Photovoltaic module characteristics from CIGS solar cell modelling
2013
We describe our approach to the task of modelling, both at single cell structure and complete module levels, during the solar cell technology development process. This can give very helpful indications, in terms of global photovoltaic module characteristics, for the assessment of intermediate research results and planning of further experiments. We make reference specifically to the fabrication of thin film CIGS solar cells by means of single-step electrodeposition, a technique which appears fairly easy and low-cost but, at the same time, can lead to quite different structural and electrical properties.
EU transition in power sector: How RES affects the design and operations of transmission power systems
2019
In the past, much of Europe's electricity grid network has been designed in consideration of the locations of conventional generation plants. However, a large share of today's renewables production – notably variable wind and solar – does not correspond to this grid architecture. Interconnectors, in addition to internal infrastructure, are key to creating new electricity corridors to connect areas of surplus to areas of scarcity. In this context, in 2014 the European Council, in recognizing that a fundamental role of transmission infrastructure is to enable the integration of areas of high renewable energy potential with main consumption areas, endorsed the proposal by the European Commissi…
Enhanced Current Loop PI Controllers with Adaptive Feed-Forward Neural Network via Estimation of Grid Impedance: Application to Three-Phase Grid-Tied…
2022
This paper describes a single-stage grid-connected three-phase photovoltaic inverter feeding power to the grid. Using the Recursive Least Squares (RLS) Estimator, an online grid impedance technique is proposed in the stationary reference frame. The method iteratively estimates the grid resistance and inductance values and is effective in detecting inverter islanding according to IEEE standard 929-2000. An Adaptive Feedforward Neural (AFN) Controller has also been developed using the inverse of the system to improve the performance of the inner-loop Proportional-Integral controllers under dynamical conditions and provide better DC link voltage stability. The neural network weights are comput…
3D ORGANIZATION OF THIN FILMS FOR THREE COMPONENTS ACTIVE LAYER IN PHOTOVOLTAIC DEVICES
2013
Polymer-fullerene or polymer-polymer based bulk heterojunction (BHJ) solar cells can be fabricated by using low-cost manufacturing methods. However, because of the low mobility of organic materials, there is a competition between separation and recombination of the photogenerated carriers within the thin BHJ film. Thus, there is a need to develop strategies to increase light harvesting in the films without increasing the film thickness. Nanoparticles (NPs) have been receiving a lot of interest for exhibiting interesting optical, electrical, and magnetic properties. These novel properties can be exploited in nanotechnology by forming compact and ordered architectures of nanoparticles within …
The potential of roofs in city centers to be used for photovoltaic micro-installations
2019
Abstract Currently in Poland, power engineering based on hard coal and lignite plays the dominant role. This significantly impedes the attainment of 15% share of energy produced from renewable sources by 2020 and has a negative impact on air quality in Poland. A solution to this unfavourable situation may be to develop renewable dispersed energy with particular emphasis on installations using photovoltaic. Strongly urbanized areas have high electricity demand, and at the same time low availability of areas where it is possible to locate renewable energy sources. In this study, the possibility of using roofs of buildings in city centres for the purpose of photovoltaic micro-installation was …
Comprehensive Analytical Investigation for PV Plants and Their Control System with Reduced Power Electronics Equipments
2012
This paper presents a comprehensive analysis of a power generation system from PV source and it control system with a reduced power equipments connected with a power AC grid. The absence of the boost chopper as an actuator for Maximum Power Point Tracking concurs to make the system more reliable, affordable and moreover cheaper respect to a traditional one in which the boost chopper is used. The mathematical analysis exposed in the paper shows as a three phase inverter has two degrees of freedom allowing the simultaneous MPPT control and the synchronization with the power grid. The analysis also shows the way to determine the duty cycle of the inverter to deliver active power, and eventuall…
Si:O Alloys for Photovoltaics: Optical and Electrical Properties from Quantum Dots to Thin Films
2010
In current Si based PV devices the sun-light-electricity conversion rarely exceeds the 20% in efficiency, stimulating significant efforts towards new solutions and technologies for giving a boost to Si for PV. One of the most promising routes for the 21st century is exploiting the quantum confinement effect in reduced dimensionality systems, with the aim to harvest the full solar spectrum. Recently, it has been proposed that a certain modulation of the optical bandgap (EG OPT) can be attained by changing the size of Si quantum dots (QDs), which should allow for a large absorption of the solar photon flux [1]. By this way, an all-Si tandem solar cell could be fabricated, by stacking solar …