Arno Smets

Working Principle of a Semiconductor Based Solar CellBand Gap I - Electrons in Atoms

Week 2.2.1

Hydrogen

Proton (+)

Electron (-)

How strong are electrons bonded: the H atom

1s

2s

3s

2p

3p

Ground state

Ener

gy

- electron

proton

+

How strong are electrons bonded: the H atom

1s

2s

3s

2p

3p

Ground state

Ener

gy

- electron

proton

+

How strong are electrons bonded: the H atom

1s

2s

3s

2p

3p

Ground state

Ener

gy

- electron

proton

+

How strong are electrons bonded: the H atom

1s

2s

3s

2p

3p

Ground state

Ener

gy

- electron

proton

+

How strong are electrons bonded: the H atom

1s

2s

3s

2p

3p

Ground state

Ener

gy

- electron

proton

+

How strong are electrons bonded: the H atom

1s

2s

3s

2p

3p

Ground state

Ener

gy

2s

3s

1s

2p

3p

X Y Z

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Electron spin

How strong are electrons bonded:

1s

2s

3s

2p

3p

Ener

gy

Pauli principle: two identical electrons can not occupy the same quantum state simultaneously.

Pauli’s Exclusion Principle:

1s

2s

3s

2p

3p

Ener

gy

Pauli principle: two identical electrons can not occupy the same quantum state simultaneously.

How strong are electrons bonded:

1s

2s

3s

2p

3p

Ener

gy

Pauli principle: two identical electrons can not occupy the same quantum state simultaneously.

Helium

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

He 1s2

Lithium

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Li 1s22s1

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Be 1s22s2

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

B 1s22s22p1

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

C 1s22s22p2

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

N 1s22s22p3

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

B 1s22s22p4

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

B 1s22s22p5

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Ne 1s22s22p6

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Na 1s22s22p63s1

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Mg 1s22s22p63s2

How strong are electrons bonded

1s

2s

3s

2p

3p

Ener

gy

Al 1s22s22p63s23p1

How strong are electrons bonded: the Si atom

1s

2s

3s

2p

3p

Ener

gy

Si 1s22s22p63s23p2

Bonding of electrons in Si network

1s

2s

3s

2p

3p

Ener

gy

Si atom: 14 electrons

Bonding of electrons in Si network

3s

3p