Influence of Defects on Solar Cell Characteristics
TL;DR: In this article, the authors reviewed the present knowledge of the origin of non-ideal I-V characteristics of silicon solar cells and introduced new results on recombination involving coupled defect levels.
Abstract: The current-voltage (I-V) characteristics of most industrial silicon solar cells deviate rather strongly from the exponential behavior expected from textbook knowledge. Thus, the recombination current may be orders of magnitude larger than expected for the given material quality and often shows an ideality factor larger than 2 in a wide bias-range, which cannot be explained by classical theory either. Sometimes, the cells contain ohmic shunts although the cell’s edges have been perfectly insolated. Even in the absence of such shunts, the characteristics are linear or super-linear under reverse bias, while a saturation would be classically expected. Especially in multicrystalline cells the breakdown does not tend to occur at -50 V reverse bias, as expected, but already at about -15 V or even below. These deviations are typically caused by extended defects in the cells. This paper reviews the present knowledge of the origin of such non-ideal I-V characteristics of silicon solar cells and introduces new results on recombination involving coupled defect levels.
Citations
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10 Oct 2011
TL;DR: The presence of defect clusters in multicrystalline silicon can influence the electronic properties of solar cells due to the interfered further crystallization and an insufficient passivation of the defects in these regions as discussed by the authors.
Abstract: The presence of defect clusters in multicrystalline silicon – not only in compensated silicon – can influence the electronic properties of solar cells. This is due to the interfered further crystallization and an insufficient passivation of the defects in these regions. Three-dimensional plots, based on hundreds of electroluminescence images, allow an improved analysis of the defect clusters’ growth during crystallization. Furthermore, this allows vertical views from any angle which is otherwise only possible with destructive vertical cuts.
2 citations
Cites background from "Influence of Defects on Solar Cell ..."
...One of the main problems of compensated Si material is reported to be the possibly problematic breakdown behavior [5, 6] which is also considered here....
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TL;DR: In this article , noise spectroscopy was applied to solar cells based on crystalline silicon with a view to evaluate the quality and reliability of this solar cell type in a reverse-biased condition where the internal structure of solar cells, as well as pn-junction itself, was electrically stressed and overloaded by a strong electric field.
Abstract: Noise spectroscopy as a highly sensitive method for non-destructive diagnostics of semiconductor devices was applied to solar cells based on crystalline silicon with a view to evaluating the quality and reliability of this solar cell type. The experimental approach was used in a reverse-biased condition where the internal structure of solar cells, as well as pn-junction itself, was electrically stressed and overloaded by a strong electric field. This gave rise to a strong generation of a current noise accompanied by local thermal instabilities, especially in the defect sites. It turned out that local temperature changes could be correlated with generation of flicker noise in a wide frequency range. Furthermore, an electrical breakdown in a nonstable form also occurred in some specific local regions what created micro-plasma noise with a two-level current fluctuation in the form of a Lorentzian-like noise spectrum. The noise research was carried out on both of these phenomena in combination with the spectrally-filtered electroluminescence mapping in the visible/near-infrared spectrum range and the dark lock-in infrared thermography in the far-infrared range. Then the physical origin of the light emission from particular defects was searched by a scanning electron microscope and additionally there was performed an experimental elimination of one specific defect by the focused ion beam milling.
1 citations
01 Dec 2012
TL;DR: In this article, a method for numerical extraction of the diode parameters (these parameters are the usually the saturation current, the ideality factor and the shunt resistance), has been investigated.
Abstract: Characteristic parameters of a device with p-n junction, namely the ideality factor n, the saturation current I s , and the Shunt resistance R sh . These parameters give a first idea of the conduction phenomena. They also inform about the performances of the device and the possibilities of optimization of its operation. In this paper, a new method for numerical extraction of the diode parameters (these parameters are the usually the saturation current, the ideality factor and the shunt resistance), has been investigated. The method is based on calculating the differentiation of the current-voltage function. The validity of this method has been confirmed by the way of current-voltage measurements of a commercial silicon sample. Results from a numerical extraction of these parameters are presented, and these results were considered in good agreement
1 citations
TL;DR: In this article , a kinked InP nanowire array solar cell architecture is proposed for high-performance solar cells, and coupled three-dimensional optoelectronic simulations are performed to investigate the optical absorption and photovoltaic conversion properties.
1 citations
References
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Book•
01 Jan 1974
TL;DR: In this article, a discussion is given of some aspects of the metal insulator transition and the status of the "minimum metallic conductivity" is discussed, and the concept is valid for liquids and in some, but not all, solid systems.
Abstract: A discussion is given of some aspects of the metal insulator transition. Particular attention is paid to the status of the “minimum metallic conductivity”. The concept is valid for liquids, and in some, but not all, solid systems.
2,109 citations
01 Sep 1957
TL;DR: In this article, the authors show that the current due to generation and recombination of carriers from generation-recombination centers in the space charge region of a p-n junction accounts for the observed characteristics.
Abstract: For certain p-n junctions, it has been observed that the measured current-voltage characteristics deviate from the ideal case of the diffusion model. It is the purpose of this paper to show that the current due to generation and recombination of carriers from generation-recombination centers in the space charge region of a p-n junction accounts for the observed characteristics. This phenomenon dominates in semiconductors with large energy gap, low lifetimes, and low resistivity. This model not only accounts for the nonsaturable reverse current, but also predicts an apparent exp (qV/nkT) dependence of the forward current in a p-n junction. The relative importance of the diffusion current outside the space charge layer and the recombination current inside the space charge layer also explains the increase of the emitter efficiency of silicon transistors with emitter current. A correlation of the theory with experiment indicates that the energy level of the centers is a few kT from the intrinsic Fermi level.
1,934 citations
"Influence of Defects on Solar Cell ..." refers background or methods in this paper
...It will be shown below that the characteristics of real solar cells behave very differently to the predictions of [2] because recombination in the depletion region contributes significantly to the cell’s total external current....
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...This large ideality factor cannot be explained with classical diode theory, and also the J02 is about 3 orders of magnitude larger than expected by [2]....
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...The classical theory of p-n junction diodes was established by Shockley [1] and was later extended by recombination in the p-n junction depletion region by Sah, Noyce, and Shockley [2]....
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...According to [2] and also to recent, more realistic numerical simulations [3], J02 should be in the order of 10 A/cm(2) for relatively poor material with a excess carrier lifetime of = 10 μs, and the ideality factor should be maximally n = 2....
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Book•
01 Oct 1981
TL;DR: In this paper, the solar source of light energy is described and quantified, along with a review of semiconductor properties and the generation, recombination, and the basic equations of photovoltaic device physics.
Abstract: Solar cell theory, materials, fabrication, design, modules, and systems are discussed. The solar source of light energy is described and quantified, along with a review of semiconductor properties and the generation, recombination, and the basic equations of photovoltaic device physics. Particular attention is given to p-n junction diodes, including efficiency limits, losses, and measurements. Si solar cell technology is described for the production of solar-quality crystals and wafers, and design, improvements, and device structures are examined. Consideration is given to alternate semiconductor materials and applications in concentrating systems, storage, and the design and construction of standalone systems and systems for residential and centralized power generation. Bibtex entry for this abstract Preferred format for this abstract
1,773 citations
"Influence of Defects on Solar Cell ..." refers methods in this paper
...It is common practice to include also these entities in a one- or two-diode model via an equivalent circuit [5]:...
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...a one-diode model, for the approximation of the I-V characteristics [5]....
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842 citations
Book•
01 Oct 1991
TL;DR: In this article, a homogeneous semiconductor at equilibrium drift, diffusion, generation, recombination, trapping and tunneling metaloxide-semiconductor capacitor P/N and other junction diodes metal-oxide semiconductor and other field effect transistors bipolar junction transistor and other bipolar transistor devices.
Abstract: Electrons, bonds, bands and holes homogeneous semiconductor at equilibrium drift, diffusion, generation, recombination, trapping and tunneling metal-oxide-semiconductor capacitor P/N and other junction diodes metal-oxide-semiconductor and other field-effect transistors bipolar junction transistor and other bipolar transistor devices.
286 citations
"Influence of Defects on Solar Cell ..." refers background in this paper
...Also modern textbooks such as Sah [4] describe the current-voltage (I-V) characteristic of solar cells on these theoretical grounds, which predicts that the reverse current-density saturates for a reverse bias below -100 mV to a constant value of -(J01 + J02)....
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...The classical theory of p-n junction diodes was established by Shockley [1] and was later extended by recombination in the p-n junction depletion region by Sah, Noyce, and Shockley [2]....
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...Also, the breakdown behavior of real (especially of MC) solar cells under reverse bias deviates significantly from the predictions in [4]....
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...According to established theory, solar cells with a base doping concentration of 10(16) cm should break down by avalanche at a reverse bias above -50 V [4]....
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...Advanced theory predicts avalanche breakdown above a certain reverse bias, which is below -50 V for typical solar cells having a base doping concentration of 10(16) cm [4]....
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