Physics of solar cells jenny nelson pdf


    Jenny Nelson duction to, and overview of, the physics of the photovoltaic cell. giving me the opportunity to teach the physics of solar cells to MSc stu-. 8 – 19 February Jenny Nelson. Department of Physics. Imperial College London. ([email protected]). Physics of Solar Cells (I). By (author):; Jenny Nelson (Imperial College, UK) The text explains the terms and concepts of solar cell device physics and shows the reader how to formulate .

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    Physics Of Solar Cells Jenny Nelson Pdf

    Each chapter ends with a list of increasingly difficult problems, many of which are answered in the appendix. The figures, which are often taken from the original. Request PDF on ResearchGate | The Physics of Solar Cells | Photons In, Electrons Out: Basic Principles of PV Jenny Nelson at Imperial College London . The Physics of Solar Cells - Nelson - Ebook download as PDF File .pdf) or view Cells - Uploaded by. emreturkoz. Solar Cell. Uploaded by.

    Working explanation[ edit ] Photons in sunlight hit the solar panel and are absorbed by semi-conducting materials. Electrons negatively charged are knocked loose from their atoms as they are excited. Due to their special structure and the materials in solar cells, the electrons are only allowed to move in a single direction. The electronic structure of the materials is very important for the process to work, and often silicon incorporating small amounts of boron or phosphorus is used in different layers. An array of solar cells converts solar energy into a usable amount of direct current DC electricity. Photogeneration of charge carriers[ edit ] When a photon hits a piece of silicon, one of three things can happen: The photon can pass straight through the silicon — this generally happens for lower energy photons. The photon can reflect off the surface. The photon can be absorbed by the silicon if the photon energy is higher than the silicon band gap value.

    Exercises and worked solutions are included. Advanced undergraduates, graduate students, and researchers in semiconductor device physics, specifically photovoltaics.

    S P Sukhatme. Lessons from Nanoelectronics. Supriyo Datta. Elements of Modern X-ray Physics. Jens Als-Nielsen. Optical Processes in Semiconductors. Jacques I. Luminescence Spectroscopy of Semiconductors.

    Ivan Pelant. Introduction to Astronomical Spectroscopy. Professor Immo Appenzeller. Introduction to XAFS. Grant Bunker. Silicon Photonics. Jamal Deen. Feynman Simplified 2C: Robert Piccioni.

    Understanding Physics. Michael Mansfield. Principles of Nano-Optics. Lukas Novotny.

    Cambridge Illustrated Handbook of Optoelectronics and Photonics. Safa Kasap. Current at the Nanoscale. Colm Durkan.

    Theory of solar cells

    Ultrafast Optics. Andrew Weiner. Electronic Properties of Materials. Rolf E. Practical Raman Spectroscopy. Peter Vandenabeele. Electronic Transport in Mesoscopic Systems. Semiconductor Optoelectronic Devices. Joachim Piprek. Introduction to Micro- and Nanooptics. Stefan Helfert. Microstructural Characterization of Materials. Wayne D.

    Topics Mike Benn. Terahertz Physics. Tools of Radio Astronomy. Kristen Rohlfs. Physics of Condensed Matter. Prasanta Misra. Electromagnetic Waves for Thermonuclear Fusion Research. Ernesto Mazzucato. Superconductivity in Nanowires.

    Alexey Bezryadin. Laser Spectroscopy 1. Fundamentals of Chemical Engineering Thermodynamics. Themis Matsoukas. The Physical Chemist's Toolbox. Robert M. Handbook of Thin Film Technology. Hartmut Frey. Adrian Kitai. Magnetism and Magnetic Materials. Optical Spectroscopy. Nikolai V. Introduction to Nanomaterials and Devices. Omar Manasreh. Quantum Nanoelectronics. Edward L.

    John Alexander. Gaetano Assanto. Nanotechnology for Microelectronics and Optoelectronics. Fernando Agullo-Rueda.

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    Solar Cells: Nanotechnology In Solar Cells Pdf

    Laser Heating Applications. Bekir Sami Yilbas. Yuan Taur. Vibration of Piezoelectric Crystal Plates. Jiashi Yang. Epitaxy of Semiconductors.

    Udo W. Advanced Thermodynamics for Engineers. Ali Turan. Small Organic Molecules on Surfaces.

    Helmut Sitter. Fundamentals and Applications of Nanophotonics. Joseph W. Debye Screening Length. Kamakhya Prasad Ghatak. Progress in Nano-Electro-Optics I. Motoichi Ohtsu. Thermodynamics of Crystalline States. These higher energy photons will be absorbed by the solar cell, but the difference in energy between these photons and the silicon band gap is converted into heat via lattice vibrations — called phonons rather than into usable electrical energy.

    The Physics of Solar Cells - Nelson

    The photovoltaic effect can also occur when two photons are absorbed simultaneously in a process called two-photon photovoltaic effect. However, high optical intensities are required for this nonlinear process. The p-n junction[ edit ] Main articles: semiconductor and p-n junction The most commonly known solar cell is configured as a large-area p-n junction made from silicon.

    As a simplification, one can imagine bringing a layer of n-type silicon into direct contact with a layer of p-type silicon.

    In practice, p-n junctions of silicon solar cells are not made in this way, but rather by diffusing an n-type dopant into one side of a p-type wafer or vice versa. If a piece of p-type silicon is placed in close contact with a piece of n-type silicon, then a diffusion of electrons occurs from the region of high electron concentration the n-type side of the junction into the region of low electron concentration p-type side of the junction.

    When the electrons diffuse across the p-n junction, they recombine with holes on the p-type side. However in the absence of an external circuit this diffusion of carriers does not go on indefinitely because charges build up on either side of the junction and create an electric field. The electric field promotes charge flow, known as drift current , that opposes and eventually balances out the diffusion of electrons and holes.

    This region where electrons and holes have diffused across the junction is called the depletion region because it contains practically no mobile charge carriers. It is also known as the space charge region, although space charge extends a bit further in both directions than the depletion region.

    Charge carrier separation[ edit ] There are two causes of charge carrier motion and separation in a solar cell: drift of carriers, driven by the electric field, with electrons being pushed one way and holes the other way diffusion of carriers from zones of higher carrier concentration to zones of lower carrier concentration following a gradient of chemical potential.

    These two "forces" may work one against the other at any given point in the cell. For instance, an electron moving through the junction from the p region to the n region as in the diagram at the beginning of this article is being pushed by the electric field against the concentration gradient. The same goes for a hole moving in the opposite direction. It is easiest to understand how a current is generated when considering electron-hole pairs that are created in the depletion zone, which is where there is a strong electric field.

    The electron is pushed by this field toward the n side and the hole toward the p side. This is opposite to the direction of current in a forward-biased diode, such as a light-emitting diode in operation. When the pair is created outside the space charge zone, where the electric field is smaller, diffusion also acts to move the carriers, but the junction still plays a role by sweeping any electrons that reach it from the p side to the n side, and by sweeping any holes that reach it from the n side to the p side, thereby creating a concentration gradient outside the space charge zone.

    In thick solar cells there is very little electric field in the active region outside the space charge zone, so the dominant mode of charge carrier separation is diffusion.

    In these cells the diffusion length of minority carriers the length that photo-generated carriers can travel before they recombine must be large compared to the cell thickness. In thin film cells such as amorphous silicon , the diffusion length of minority carriers is usually very short due to the existence of defects, and the dominant charge separation is therefore drift, driven by the electrostatic field of the junction, which extends to the whole thickness of the cell.

    This reverse current is a generation current, fed both thermally and if present by the absorption of light. On the other hand, majority carriers are driven into the drift region by diffusion resulting from the concentration gradient , which leads to the forward current; only the majority carriers with the highest energies in the so-called Boltzmann tail; cf.

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