Simulation of Solar Cell with Silvaco ATLAS25.2.2010

Solar cell

• pn-junction• Under illumination:

– Charge carriers are generated in the depletion region Electric field separates electrons and holes

Photocurrent

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Solar cell – IV characteristics

• Photocurrent JL generates voltage V in the load resistor RVoltage V opens the pn-junction (forward bias)Normal diode current (here leakage)Reduction of total current

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Max power area

( ) LTkqV

s JeJJ B −−= 1

Normal diode current

Photocurrent

Silvaco ATLAS device simulation software

• http://www.silvaco.com/• Simulation of the electrical, optical, and thermal

behavior of semiconductor devices• Analysis of DC, AC, and transient responses• 2D or 3D• Based on finite element method (FEM)

n-type silicon

Model structure

p-type silicon

Light

Back contact

75 nm anti reflective SiNcoating

1000 μm

400 μm

Front contact

Not in scale.y

x

Simulation steps

1. Creation of grid2. Definition of material parameters, doping, traps etc.3. Solution in thermodynamical equilibrium4. Calculation of IV-curve under illumination

Creation of grid

• More dense grid near important points (edges, interfaces, electrodes)

0 100 200 300 400 500 600 700 800 900 1000

-100

0

100

200

300

400

Microns

Mic

rons

anode

cathode

Doping and trap profiles

1,0E+09

1,0E+10

1,0E+11

1,0E+12

1,0E+13

1,0E+14

1,0E+15

1,0E+16

1,0E+17

1,0E+18

1,0E+19

1,0E+20

1,0E+21

0,0 0,5 1,0 1,5 2,0 2,5 3,0

y (microns)

Dop

ing

dens

ity (c

m-3

)

DonorsAcceptors

0 0.5 1 1.5 2 2.5 3

10

11

12

13

14

15

16

17

18

Microns

Donor Trap DOS #1 (/cm3)

Doping profile Trap state density profile

y ( )

Solution in thermodynamical equilibrium

0 100 200 300 400 500 600 700 800 900 1000

0

100

200

300

400

Microns

Mic

rons

anode

cathode

Potential (V)

-0.329-0.271-0.213-0.154-0.0962-0.03790.02040.07870.1370.1950.2540.3120.370.4280.4870.5450.603

Electric potential

0 100 200 300 400 500 600 700 800 900 1000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Microns

Mic

rons

Potential (V)

-0.329-0.271-0.213-0.154-0.0962-0.03790.02040.07870.1370.1950.2830.3410.3990.4580.5450.603

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

-0.4

-0.2

0

0.2

0.4

0.6

Microns

Potential (V)

IV-curve under illumination

-3

-2

-1

0

1

2

3

0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70

Voltage (V)

Cur

rent

den

sity

(A/c

m2 )