36
A. Shah
Interaction of light with matter, such as the generation of electron-hole
pairs in solar cell, is treated on the based on the representation of light as
composed of particles.
6. Relevant constants
Charge of the electron q ≈ 1.602 × 10
−19 C
Mass of the electron m e ≈ 9.105 × 10
−31 kg
Constant of Planck h ≈ 6.626 × 10
−34 kg m
2 s
−1
Speed of light c ≈ 2.998 × 10
8 m s
−1
Boltzmann Constant k ≈ 1.3807 × 10
−23 m
2 kg/(s
2 K).
7. Bandgaps and equivalent wavelengths at 25 °C
Material
Bandgap Eg
[eV]
Equivalent
wavelength λ
[nm]
Comments
(nature of gap;
see Sect. 3.2.2)
Use
Ge
0.67
1850
Indirect
Substrates for
space solar cells
Si
1.14
1088
Indirect
Used today for
>90% of solar
cells
CdTe
1.50
827
Direct
Used today for
thin-film solar
cells
GaAs
1.43
867
Direct
Basis of space
solar cells
Amorphous
silicon
1.75
710
Eg ≈
1.7–1.85 eV
Non-direct
Used today for
solar cells
within pocket
calculators
8. Range of visible light
The range of visible light extends from 380 to 760 nm. Expressed in photon
energies, this range extends from 1.63 to 3.27 eV.
9. Quick aid to convert wavelengths into Photon energies and back
The easiest way is to use the following expressions:
E[eV] ≈
1.24
λ[µm]
λ[µm] ≈
1.24
E[eV]