Chapter 4
Solar Cells: Optical and Recombination
Losses
Sylvère Leu and Detlef Sontag
Abstract In Sect. 4.1 on Optical Losses, we first look at the absorption of light in a
semiconductor, distinguishing thereby between semiconductors with direct transition
(direct bandgaps), like GaAs, CdTe etc. and semiconductors with indirect transitions
(indirect bandgaps) like silicon. Thereafter we introduce various methods for achieving trapping of the light within the semiconductor, such as (a) the introduction of an
ARC (antireflection coating layer), (b) texturing of the front and the back surfaces,
(c) mirror formation on the back side of the solar cell. In Sect. 4.2 on Recombination, we will introduce the four main types of recombination processes (a) radiative
recombination, (b) Shockley-Read-Hall (SRH) recombination, (c) Auger recombination and (d) surface recombination. In Chaps. 5 and 7 we will apply this basic
information to design highly efficient solar cells.
4.1 Optical Losses
The losses of a solar cell can be divided into three categories:
1. Optical losses
2. Losses due to recombination
3. Ohmic losses.
In this chapter, we cover the basics of optical losses and recombination losses.
Ohmic losses occur mainly when individual solar cells are assembled into entire
modules; they will find application in Chaps. 9 and 10.
S. Leu · D. Sontag (B)
Meyer Burger Technology A.G., Gwatt, Switzerland
e-mail: dsontag@web.de
S. Leu
e-mail: sylvere.leu@ciptec.ch
© Springer Nature Switzerland AG 2020
A. Shah (ed.), Solar Cells and Modules, Springer Series in Materials Science 301,
https://doi.org/10.1007/978-3-030-46487-5_4
73
Solar Cells: Optical and Recombination
Losses
Sylvère Leu and Detlef Sontag
Abstract In Sect. 4.1 on Optical Losses, we first look at the absorption of light in a
semiconductor, distinguishing thereby between semiconductors with direct transition
(direct bandgaps), like GaAs, CdTe etc. and semiconductors with indirect transitions
(indirect bandgaps) like silicon. Thereafter we introduce various methods for achieving trapping of the light within the semiconductor, such as (a) the introduction of an
ARC (antireflection coating layer), (b) texturing of the front and the back surfaces,
(c) mirror formation on the back side of the solar cell. In Sect. 4.2 on Recombination, we will introduce the four main types of recombination processes (a) radiative
recombination, (b) Shockley-Read-Hall (SRH) recombination, (c) Auger recombination and (d) surface recombination. In Chaps. 5 and 7 we will apply this basic
information to design highly efficient solar cells.
4.1 Optical Losses
The losses of a solar cell can be divided into three categories:
1. Optical losses
2. Losses due to recombination
3. Ohmic losses.
In this chapter, we cover the basics of optical losses and recombination losses.
Ohmic losses occur mainly when individual solar cells are assembled into entire
modules; they will find application in Chaps. 9 and 10.
S. Leu · D. Sontag (B)
Meyer Burger Technology A.G., Gwatt, Switzerland
e-mail: dsontag@web.de
S. Leu
e-mail: sylvere.leu@ciptec.ch
© Springer Nature Switzerland AG 2020
A. Shah (ed.), Solar Cells and Modules, Springer Series in Materials Science 301,
https://doi.org/10.1007/978-3-030-46487-5_4
73