Working Principle of a Semiconductor Based Solar Cell Semiconductor - - PowerPoint PPT Presentation

▶

Jul 31, 2023 141 likes •314 views

Working Principle of a Semiconductor Based Solar Cell Semiconductor Junction II - The Solar Cell Week 2.4.2 Arno Smets Semiconductor Junction Thermal Equillibrium No net current - - - - + + + + - - - - + + + + p region n

SLIDE 1

Arno Smets

Working Principle of a Semiconductor Based Solar Cell

Semiconductor Junction II - The Solar Cell

Week 2.4.2

SLIDE 2

Semiconductor Junction – Thermal Equillibrium

+ + + + + + + + + + + + + + + + + + +

n region p region

Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

No net current

SLIDE 3

Semiconductor Junction – Forward Bias

+ + + + + + + + + + + + + + + + + + +

n region p region

+

Field reduced

Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

SLIDE 4

Semiconductor Junction – Forward Bias

n region p region

+

Field reduced
+

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Net current!

SLIDE 5

EF EF

drift diffusion drift diffusion

SLIDE 6

EF EF

drift diffusion drift diffusion

SLIDE 7

EF EF

drift diffusion drift diffusion

SLIDE 8

EF EF

drift diffusion drift diffusion qV

SLIDE 9

Semiconductor Junction – Reverse Bias

n region p region

Field increased

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

SLIDE 10

Semiconductor Junction – Reverse Bias

n region p region

Field increased

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Extremely Small Net current!

SLIDE 11

Semiconductor Junction – under illumination

n region p region

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

SLIDE 12

Semiconductor Junction – under illumination

n region p region

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

SLIDE 13

Short Circuit

n region p region

+ + + + + + + + + + + + + + + + + + +

SLIDE 14

Open Circuit

n region p region

+ + + + + + + + + + + + + + + + + + +

V E Field

SLIDE 15

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

SLIDE 16

Working Principle of a Semiconductor Based Solar Cell

Semiconductor Junction II - The Solar Cell

Week 2.4.2

Semiconductor Junction – Thermal Equillibrium

+ + + + + + + + + + + + + + + + + + +

n region p region

Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

No net current

Semiconductor Junction – Forward Bias

+ + + + + + + + + + + + + + + + + + +

n region p region

+

Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Semiconductor Junction – Forward Bias

n region p region

+

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Net current!

EF EF

drift diffusion drift diffusion

EF EF

drift diffusion drift diffusion

EF EF

drift diffusion drift diffusion

EF EF

drift diffusion drift diffusion qV

Semiconductor Junction – Reverse Bias

n region p region

Field increased

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Semiconductor Junction – Reverse Bias

n region p region

Field increased

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Extremely Small Net current!

Semiconductor Junction – under illumination

n region p region

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Semiconductor Junction – under illumination

n region p region

+ + + + + + + + + + + + + + + + + + + Electron Diffusion Je = qDedn/dx Electron Drift Je = nqeE Hole Drift Jh = pqhE Hole Diffusion Jh= qDhdp/dx

Short Circuit

n region p region

+ + + + + + + + + + + + + + + + + + +

Open Circuit

n region p region

+ + + + + + + + + + + + + + + + + + +

V E Field

p-n junction Solar Cells

Three essential steps required for the operation of a solar cell:

2. Separation of electron and hole at the junction 3. Collection of electrons and holes at the terminals

Thank you for your attention!