working principle of a semiconductor based solar...
TRANSCRIPT
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Arno Smets
Working Principle of a Semiconductor Based Solar CellSemiconductor Junction II - The Solar Cell
Week 2.4.2
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Semiconductor Junction – Thermal Equillibrium
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+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
n regionp region
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
No net current
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Semiconductor Junction – Forward Bias
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+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
n regionp region
+ -Field reduced
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
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Semiconductor Junction – Forward Bias
n regionp region
+ -Field reduced- - - -
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+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
Net current!
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EF EF
driftdiffusion
driftdiffusion
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EF
EF
driftdiffusion
driftdiffusion
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EF
EF
driftdiffusion
driftdiffusion
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EF
EF
driftdiffusion
driftdiffusion
qV
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Semiconductor Junction – Reverse Bias
n regionp region
- +Field increased- - - -
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+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
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Semiconductor Junction – Reverse Bias
n regionp region
- +Field increased- - - -
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- - - -
+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
Extremely Small Net current!
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Semiconductor Junction – under illumination
n regionp region
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+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
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Semiconductor Junction – under illumination
n regionp region
- - - -
- - - -
- - - -
- - - -
- - - -
+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
Electron Diffusion Je = qDedn/dxElectron Drift Je = nqeE
Hole Drift Jh = pqhEHole Diffusion Jh = qDhdp/dx
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Short Circuit
n regionp region
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+ + + +
+ + + +
+ + + +
+ + + +
+ + + +
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Open Circuit
n regionp region
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+ + + +
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V
E Field
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p-n junction Solar Cells
Three essential steps required for the operation of a solar cell:
1. Generation of electron-hole pairs in the cell
2. Separation of electron and hole at the junction
3. Collection of electrons and holes at the terminals
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Thank you for your attention!