Lecture

Photovoltaics: fundamentals and efficiency

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In course

MICRO-566: Large-area electronics: devices and materials

Introduction to the physical concepts involved in the description of optical and electronic transport properties of thin-film semiconductor materials found in many large-area applications (solar cells, displays, imagers, etc) and introduction to the physic ...

Description

This lecture covers the fundamentals of photovoltaics, including the photovoltaic effect discovered by Edmund Becquerel in 1839, the absorption process in semiconductors, bandgap optimization for spectral efficiency, electron-hole pair separation in solar cells, and the Shockley-Queisser limit. It also discusses the efficiency factors such as fill-factor, open-circuit voltage, and short-circuit current, as well as practical and theoretical efficiency limits. The lecture concludes with advanced topics like multijunction solar cells and the availability of materials for photovoltaics.

Instructors (2)

Christophe Ballif

Christophe Ballif is director of the Phototovoltaics and Thin Film Electronics Laboratoryb) (PV-Lab at the institute of microengineering (IMT) in Neuchâtel (part of the EPFL since 2009). The lab focus is on the science and technology of high efficiency heterojunction crystalline cells,so-called passivating contacts for solar cells, multi-junction solar cells include novel generation Perovskite on innovative optical high speed detector and on various macroelectronics application. It also deals with energy management with a focus on integration of solar electricity into the energy system. The PV-Lab has strongly contributed to technology transfer and industrialization of novel devices and full technology with numerous companies. Christophe Ballif graduated as a physicist from the EPFL in 1994, where he also obtained in 1998 his Phd degree working on novel PV materials. He accomplished his postdoctoral research at NREL (Golden, US) on compound semiconductor solar cells (CIGS and CdTe). He worked then at the Fraunhofer ISE (Ge) on crystalline silicon photovoltaics (monocrystalline and multi-crystalline) until 2003 and then at the EMPA in Thun (CH) before becoming full professor at the University of Neuchâtel IMT in 2004, taking over the chair of Prof. A. Shah. Since 2013, C.Ballif is also the director of the new CSEM PV-Center, also located in Neuchâtel. The CSEM PV-Center is focussing more on industrialisation and technology transfer in the field of solar energy, including solar electricity management and storage. At the core of the CSEM PV-center activities lies several "pilot lines" for various kinds of solar cells manufacturing, with a focus coating technologies, wet chemistry processes for crystalline silicon, metalisation techniques for solar cells, and a platform for developing "ideal packaging solutions and polymers" for PV modules. In addition, joined facitilites between CSEM and EPFL of over 800 m2 are available for modules manufacturing, measuring and accelerated aging. CSEM PV-center has also full team dedicated to storage and energy systems and operates a joined center with BFH in Biel for research on electrochemical storage. He (co-) authored over 500 journal and technical papers, as well as several patents. He is an elected member of the SATW, member of the scientific council of the Swiss AEE, and member of the board of the EPFL Energy center. In 2016, he recieved the Becquerel prize for his contributions to the field of high efficiency photovoltaics.

Franz-Josef Haug

I studied Physics between 1990 and 1996 at the Universities of Ulm (Germany) and Waikato (New Zealand). While specializing mostly on Theoretical Physics and Quantum Theory during my studies, I turned towards Experimental Physics for a graduate work on gas-phase epitaxy of silicon. After that, I pursued a PhD program at ETH Zürich (Switzerland), studying Cu(In,Ga)Se2 solar cells. As PostDoc, I went to EMPA (Switzerland) to work on plasma processes for hard coatings of TiN and to the Jülich Research Centre in Germany to study light scattering ZnO front contacts for solar cells. In 2005 I joined the Institute of Microengineering (IMT) at the University of Neuchatel to lead a research group on thin film silicon solar cells within the PV-Lab. In 2009 the IMT was integrated into EPFL. My main research interests are optics, charge transport in semiconductors and renewable energy in general. My current work is devoted to passivating contacts for crystalline silicon solar cells, using thin silicon films as contact layers. In 2015 I was appointed Maitre d'Enseignement et Recherche (Senior Lecturer and Scientist) and member of the Faculty of STI. From 2013 to 2015 I was member of the EFPL Teachers Council (CCE) and from 2016 and 2018 I was elected into the Council of the Engineering School (CF-STI). In 2020 I was elected to become a member of CF-STI. My main objective for the legislature is to represent the role of EPFL's intermediate staff and to raise the awareness for concerns of the satellite campuses.

Official source

Ontological neighbourhood

Energy engineering

Solar power: Topics in solar power

Related concepts (32)

Solar cell research

There are currently many research groups active in the field of photovoltaics in universities and research institutions around the world. This research can be categorized into three areas: making current technology solar cells cheaper and/or more efficient to effectively compete with other energy sources; developing new technologies based on new solar cell architectural designs; and developing new materials to serve as more efficient energy converters from light energy into electric current or light absorbers and charge carriers.

Solar cell

A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical phenomenon. It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light. Individual solar cell devices are often the electrical building blocks of photovoltaic modules, known colloquially as solar panels.

Solar panel

A solar panel is a device that converts sunlight into electricity by using photovoltaic (PV) cells. PV cells are made of materials that generate electrons when exposed to light. The electrons flow through a circuit and produce direct current (DC) electricity, which can be used to power various devices or be stored in batteries. Solar panels are also known as solar cell panels, solar electric panels, or PV modules. Solar panels are usually arranged in groups called arrays or systems.

Organic solar cell

An organic solar cell (OSC) or plastic solar cell is a type of photovoltaic that uses organic electronics, a branch of electronics that deals with conductive organic polymers or small organic molecules, for light absorption and charge transport to produce electricity from sunlight by the photovoltaic effect. Most organic photovoltaic cells are polymer solar cells. The molecules used in organic solar cells are solution-processable at high throughput and are cheap, resulting in low production costs to fabricate a large volume.

Thin-film solar cell

Thin-film solar cells are made by depositing one or more thin layers (thin films or TFs) of photovoltaic material onto a substrate, such as glass, plastic or metal. Thin-film solar cells are typically a few nanometers (nm) to a few microns (μm) thick–much thinner than the wafers used in conventional crystalline silicon (c-Si) based solar cells, which can be up to 200 μm thick. Thin-film solar cells are commercially used in several technologies, including cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous thin-film silicon (a-Si, TF-Si).

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