Search results for "OPEN-CIRCUIT VOLTAGE"
showing 10 items of 63 documents
Simulated and measured temperature coefficients in compensated silicon wafers and solar cells
2019
Abstract In this paper we perform a thorough investigation of the temperature coefficients of c-Si solar cells and wafers, based on both experimental data and device simulations. Groups of neighboring wafers were selected from different heights of four high performance multicrystalline silicon ingots cast using different dopants concentrations and Si feedstocks; Three different target resistivities of compensated silicon ingots based on Elkem Solar Silicon (ESS®), which are purified through a metallurgical route, and one non-compensated reference ingot. The wafers were processed into Al-BSF and PERCT type solar cells, as well as into lifetime samples subjected to selected solar cell process…
Improvement of DSSC performance by voltage stress application
2016
Dye-sensitized solar cells (DSSCs) are promising third generation photovoltaic devices given their potential low cost and high efficiency. Some factors still affect DSSCs performance, such structure of electrodes, electrolyte compositions, nature of the sensitizers, power conversion efficiency, long-term stability, etc. In this work we discuss the effect of electrical stresses, which allow to improve DSSC performance. We have investigated the outcomes of forward and reverse DC bias stress as a function of time, voltage, and illumination level in the DSSCs sensitized with the N719, Ruthenium complex based dye. We demonstrate that all the major solar cell parameters, i.e., open circuit voltag…
Investigation of recovery mechanisms in dye sensitized solar cells
2016
Abstract We study the spontaneous recovery phenomenon displayed by solar cells sensitized with a ruthenium complex-based dye N719, which manifests with the increase over the time (from several minutes up to some days) of the short circuit current density J sc and the open circuit voltage V oc , during cell illumination. Under dark conditions the current decreases over time after the application of forward bias voltages. We investigate the effects of temperature and electrolyte composition by means of current–voltage measurements and electrochemical impedance spectroscopy, both under dark and illumination conditions. The main result is that the recovery of the performances depends on the cha…
Hybrid Tribo-Piezo-Electric Nanogenerator with Unprecedented Performance Based on Ferroelectric Composite Contacting Layers
2019
This research was supported by the European Regional Development Fund within the project ‘‘Hybrid energy harvesting systems’’ 1.1.1.1./16/A/013.
A new analytical solar cell I–V curve model
2011
Abstract A simple mathematical equation that can represent empirical I–V curves of individual solar cells, systems of solar cells and modules has been found. The basic model is determined by four parameters: the open circuit voltage, the short circuit current and two shape parameters. With the four parameters determined, the complete current–voltage curve, the fill factor and the maximum power point are given by simple analytical functions. The model is valid both in the positive and the negative (dark condition) voltage range. Several simple examples demonstrate some of the potential of the model. Due to its mathematical simplicity, it is suggested that the model will be suitable for analy…
Radiative efficiency of lead iodide based perovskite solar cells
2014
The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.1…
Tensiostatic studies on formation and breakdown of anodic oxide films on tungsten in acidic chloride solutions
1977
Abstract The anodic behaviour of tungsten in HCl and HCl + KCl solutions has been extensively studied. For each solution, the applied voltage was increased from 1 V up to the breakdown voltage. Values of the current and open circuit voltage decays were recorded. The HCl concentration was varied from 0.05 M to 12 M while appropriate addition to KCl was made to reach assigned molarities of the Cl − ion. The results are discussed and qualitatively interpreted in terms of the different influence of the H + and Cl − ions.
The effect of thickness on the composition of passive films on a Ti–50Zr at% alloy
2006
Abstract Anodic films were grown potentiodynamically in different electrolytes (pH = 1–14) on a Ti–50Zr at% cast alloy, obtained by fusion in a voltaic arc under argon atmosphere. The thickness of the films was varied by changing formation potential from the open circuit potential up to about 9 V; growth was followed by 30 min stabilization at the forming potential. Films having different thicknesses were characterized by photocurrent spectroscopy (PCS) and electrochemical impedance spectroscopy (EIS). Moreover, film composition was analyzed by X-ray photoelectron spectroscopy (XPS). Regardless of the anodizing conditions, passive films on the Ti–50Zr at% alloy consist of a single layer mix…
Quantification of spatial inhomogeneity in perovskite solar cells by hyperspectral luminescence imaging
2016
Vacuum evaporated perovskite solar cells with a power conversion efficiency of 15% have been characterized using hyperspectral luminescence imaging. Hyperspectral luminescence imaging is a novel technique that offers spectrally resolved photoluminescence and electroluminescence maps (spatial resolution is 2 micrometer) on an absolute scale. This allows, using the generalized Planck’s law, the construction of absolute maps of the depth-averaged quasi-Fermi level splitting (Δμ), which determines the maximum achievable open circuit voltage (Voc) of the solar cells. In a similar way, using the generalized reciprocity relations the charge transfer efficiency of the cells can be obtained from the…
Ideality factor behavior between the maximum power point and open circuit
2013
The local ideality factor analysis of dark and light I-V curves has been used in the past to study various performance degradation effects in solar cells. Trapping, edge recombination and injection-level-dependent recombination are expressed as “lumps, humps and bumps” in the plots of the local ideality factor over cell voltage (m-V plots). Earlier applications of this differential technique did not correct the plots for the series resistance effect. Thus, the bumps at the higher voltages introduced by some mechanisms were more difficult to quantify. A possible solution is to analyze ISC-VOC curves, but their measurement is not always possible. We present a formula for calculation of the RS…