Solar Cell Operation, Performance and Design Rules Light Trapping - - PowerPoint PPT Presentation

▶

Sep 02, 2023 302 likes •600 views

Solar Cell Operation, Performance and Design Rules Light Trapping II - Anti-Reflection and Trapping Methods Week 3.3.5 Arno Smets Parasitic losses = outside absorbing layers 2 Al Al Reflection 2 n+ N+ p-type 4 Transmission C-Si 4

SLIDE 1

Arno Smets

Solar Cell Operation, Performance and Design Rules

Light Trapping II - Anti-Reflection and Trapping Methods

Week 3.3.5

SLIDE 2

Parasitic losses = outside absorbing layers

p-type C-Si

Al

Al Al P++ P++

N+

n+ 2

Reflection

2 4

Transmission

4

SLIDE 3

Parasitic losses = outside absorbing layers

p-type C-Si

Al

Al Al P++ P++

N+

n+ 2

Reflection

2

SLIDE 4

Snell’s Law

i t r n1 n2

r i t 2 i 1

sin n sin n      

SLIDE 5

r i t 2 i 1

sin n sin n      

i t r n1 n2

The Fresnel equation

SLIDE 6

P- and S- polarization

P-polarization S-polarization

SLIDE 7

Fresnel coefficients

2 i 2 t 1 i 2 t 1 p

) cos( n ) cos( n ) cos( n ) cos( n R               

2 t 2 i 1 t 2 i 1 S

) cos( n ) cos( n ) cos( n ) cos( n R               

p p

R 1 T  

s S

R 1 T   P-polarization S-polarization

SLIDE 8

Reflection coefficient (n1 < n2)

Rs , Rp (%) Angle of Incidence i (o) 20 40 60 80 20 40 60 80 100 Brewster Angle

P-polarization S-polarization

n1=1.0 n2=1.5

SLIDE 9

Reflection coefficient (n1 > n2)

Rs , Rp (%) Angle of Incidence i (o) 20 40 60 80 20 40 60 80 100

P-polarization S-polarization

Total internal reflection n1=1.5 n2=1.0

SLIDE 10

Reflection coefficient (n1 > n2)

Rs , Rp (%) Angle of Incidence i (o) 20 40 60 80 20 40 60 80 100

P-polarization S-polarization

n1=1.5 n2=1.0 crit = 41.8o Total internal reflection

SLIDE 11

Reduction Front Reflection:

n0 ns

2 s 2 s s

) n n ( ) n n ( R   

 

2 s s s

n n n n 4 T  

SLIDE 12

Reduction Front Reflection:

n0 ns

R0s = 0.388 T0s = 0.612

SLIDE 13

 

2 s s s

n n n n 4 T  

N1 Ns

2 s 1 2 s 1 s 1

) n n ( ) n n ( R   

2 1 2 1 01

) n n ( ) n n ( R   

Rayleigh film First order approximation

N0

 

2 1 1 01

n n n n 4 T  

SLIDE 14

10 0.8 0.6 0.4 0.2 0.0

Refractive Index n1 Total Reflection

1.0 1.5 2.0 2.5 3.0 3.5 4.0

For siliconand air: @ 500 nm Ns N0

1 . 2 3 . 4 1 n n n

S 1

   

Lower reflection coeff

SLIDE 15

N1=2.07 Ns=4.3 N0=1 air silicon silicon Anti-reflection

612 . T s

0 

T

eff = 0.771

388 . R s

0 

229 . Reff 

air

SLIDE 16

Interference:

SLIDE 17

Interference:

constructive Interference =0 destructive Interference =

SLIDE 18

Interference: the anti-reflection coating

Destructive interference Ei Er1 Er2 =

n 4 d  

SLIDE 19

Macroscopic roughness (d>>)

Path of light rays Are determined By refraction.

Reflected Incident light 36 Reflected

SLIDE 20

Parasitic losses = outside absorbing layers

p-type C-Si

Al

Al Al P++ P++

N+

n+ 4

Transmission

4

SLIDE 21

Enhancement of Absorption path length in Thin Film Solar cells

0i 0i 0i 0i 0i 0i 0i i< critical

SLIDE 22

100 80 60 40 20 40 60 80

Angle of Incidence 0i (o) Rs , Rp ( % )

Total internal reflection

SLIDE 23

Enhancement of Absorption path length in Thin Film Solar cells

i< critical

SLIDE 24

Enhancement of Absorption path length in Thin Film Solar cells

SiO2 silicon n2=1.5 n2=1.5 n1=4.3 SiO2

SLIDE 25

Enhancement of Absorption path length in Thin Film Solar cells

ZnO silicon N2=2.2 n2=2.2 n1=4.3 ZnO

SLIDE 26

Light management in solar cells

Ld Increasing the absorption path length

SLIDE 27

Thank you for your attention!

SLIDE 28

a `