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Counting sunrays: from optics to the thermodynamics of light

Counting sunrays: from optics to the thermodynamics of light
Counting sunrays: from optics to the thermodynamics of light
This chapter considers quantum solar energy conversion from a thermodynamic point of view. Starting from geometrical optics, the concept of étendue is used to determine the number of photon states in a beam of light. This naturally leads to the definition of entropy, providing the foundation for the statistical mechanics of light beams. With emphasis on the thermodynamic functions per photon (in particular, the chemical potential), these concepts are illustrated first by comparing the thermodynamic limits of the geometric concentrators with the limits obtained by traditional arguments. The thermodynamic framework is then extended to novel applications. The fluorescent collector is modelled as an open thermodynamic system interacting with a room-temperature heat bath. A detailed thermodynamic description of the operation of a p-n junction solar cell then follows, starting from energy (voltage) rather than from the kinetic argument used by Shockley and Queisser. This provides a novel view of fundamental losses, each identified as a specific form of irreversible entropy generation. The chapter concludes with an analysis of a future photovoltaic device – a hot carrier solar cell where the voltage exceeds the Shockley-Queisser limit. The efficiency of this solar cell, obtained by thermodynamic arguments, is free from specific mechanisms or structures such as selective energy contacts. It is argued that this is the fundamental efficiency limit to the operation of single junction solar cells where thermalization of electron-hole pairs has been reduced or entirely eliminated
160876110X
Nova Science Publishers
Markvart, Tom
f21e82ec-4e3b-4485-9f27-ffc0102fdf1c
Badescu, Viorel
Paulescu, Marius
Markvart, Tom
f21e82ec-4e3b-4485-9f27-ffc0102fdf1c
Badescu, Viorel
Paulescu, Marius

Markvart, Tom (2009) Counting sunrays: from optics to the thermodynamics of light. In, Badescu, Viorel and Paulescu, Marius (eds.) Physics of the Nanostructured Solar Cells. New York, USA. Nova Science Publishers.

Record type: Book Section

Abstract

This chapter considers quantum solar energy conversion from a thermodynamic point of view. Starting from geometrical optics, the concept of étendue is used to determine the number of photon states in a beam of light. This naturally leads to the definition of entropy, providing the foundation for the statistical mechanics of light beams. With emphasis on the thermodynamic functions per photon (in particular, the chemical potential), these concepts are illustrated first by comparing the thermodynamic limits of the geometric concentrators with the limits obtained by traditional arguments. The thermodynamic framework is then extended to novel applications. The fluorescent collector is modelled as an open thermodynamic system interacting with a room-temperature heat bath. A detailed thermodynamic description of the operation of a p-n junction solar cell then follows, starting from energy (voltage) rather than from the kinetic argument used by Shockley and Queisser. This provides a novel view of fundamental losses, each identified as a specific form of irreversible entropy generation. The chapter concludes with an analysis of a future photovoltaic device – a hot carrier solar cell where the voltage exceeds the Shockley-Queisser limit. The efficiency of this solar cell, obtained by thermodynamic arguments, is free from specific mechanisms or structures such as selective energy contacts. It is argued that this is the fundamental efficiency limit to the operation of single junction solar cells where thermalization of electron-hole pairs has been reduced or entirely eliminated

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Published date: December 2009
Organisations: Engineering Mats & Surface Engineerg Gp

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Local EPrints ID: 69617
URI: https://eprints.soton.ac.uk/id/eprint/69617
ISBN: 160876110X
PURE UUID: 3a45a43a-7c89-4ab3-ba10-1078cb99cd0b

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Date deposited: 20 Nov 2009
Last modified: 19 Jul 2017 00:11

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Contributors

Author: Tom Markvart
Editor: Viorel Badescu
Editor: Marius Paulescu

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