# Solar Cell Pc1D Assignment 1

Topics: Solar cell, Band gap, Semiconductor Pages: 17 (1518 words) Published: May 24, 2013
Part A
A 2.1 Table A.1 Design and Performance Parameters Design
parameters
!! ������������������������  ������������������������������������(������������ )   3.78×10!"
������������������������ℎ  ������������������������������������(������������)   14.5
38.49
������ℎ������������������  ������������������������������������������������������������  (������/☐)
0.10467
Emitter
contact(Ω)
Junction
Depth  (������������)
21.05
Performance
parameters
0.608
������ " （������)   ! 2)
������!" (mA/cm 32.87
������������
0.818
������
16.4%
A 2.2

I-­‐V
curve
&
Power
curve

0.04
0.035
0.03
0.025
Current
(A)
0.02
0.015
0.01
0.005
0
-­‐0.2
-­‐0.005
-­‐0.01
-­‐0.015
Voltage
(V)

Figure A.1 I-V and Power curve of best emitter design

Isc=0.03287A

I-­‐V
curve
(A)
Power
curve
(W)

Pmax=0.0164W

Voc=0.608V
0
0.2
0.4
0.6
0.8

A 2.4 Junction depth (xj) is the distance at which the concentration of n type (or p type) dopants equates to the p type (or n type) background concentration CB. Depth factor is diffusion lengthλwhich equals to 4������������.  In the case of realistic

profiles it is the distance at which the Concentration of the diffusing atoms drops to a characteristic lower value. For example，about 0.3 for a Gaussian concentration profile. A2.5 For commercially produced screen-printed solar cells, the surface doping concentration is about 1×10!" ~1×10!" ������������������������������/������������! . It is nearly the solid   solubility

of
phosphorus
in
silicon
substrate.

On
the
other
hand,
the
junction
depth
is
about
0.3~0.5  ������������.

A2.6 By comparing design parameters from A2.1 and commercially parameters from A2.5, it is clearly to see that commercial solar cells usually have thinner junction depth and heavier surface doping level. The probable reason can be got from the following figure.

Figure A.2 The light-generated current depends on the generation of carriers and the collection probability of these carriers.

Usually, the peak of generation rate is near the surface, however, at this time, the collection rate is low. So in realistic case, people try to minimize the junction depth to collect carriers as much as possible. On the other hand, diffusion process requires a lot of time. If the junction depth is more than 20um, it will cost a lot of time and money to do the diffusion process, which is very inefficient and uneconomic. For realistic case, commercial solar cell has a higher surface doping concentration; hence decrease the sheet resistance of solar cells. Larger sheet resistance means using fewer grid lines of the top contact.

Part B
B 2.1 Table B.1 Design and Performance Parameters Design
parameters
!! ������������������������  ������������������������������������(������������ )   5.71×10!"
������������������������ℎ  ������������������������������������(������������)   137.436
3.871
������ℎ������������������  ������������������������������������������������������������  (������/☐)
Junction
Depth  (������������)
137.4
Performance
parameters
0.6790
������ " （������)   ! 2)
������!" (mA/cm 33.4
������������
0.803
������
18.6%
B 2.2

I-­‐V
curve
&
Power
curve

0.04
0.035
0.03
0.025
Current
(A)
0.02
0.015
0.01
0.005
0
-­‐0.2
-­‐0.005
-­‐0.01
-­‐0.015
Voltage
(V)

Figure B.1 I-V and Power curve of best back surface field design

Isc=0.0334A

I-­‐V
curve
(A)
Power
curve
(W)

Pmax=0.0186W

Voc=0.6790V
...

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