Introduction to solar cells week 3 part D

Introduction to solar cells

week 3 part d

link to join this course https://www.coursera.org/learn/solar-cells

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1.Question 1

First and second generation solar cells are defined as silicon solar cells and thin film solar cells respectively.

Please select the correct statement(s) regarding first and second generation solar cells.

First generation solar cells use in-direct bandgap materials

Correct

That is correct

Silicon is an in-direct bandgap material and therefore silicon needs to be relatively thick (>100 micrometer) in order to absorb sufficient light.

First generation solar cells use direct bandgap materials

First generation solar cells are typically thicker than second generation solar cells

Correct

That is correct

The second generation of solar cells are defined as thin film solar cells, since they are comprised of direct bandgap materials, which can absorb light even with thinner layers.

First generation solar cells are typically thinner than second generation solar cells

1 / 1 point

2.Question 2

We want to compare two different types of solar cells with regard to their losses due to reflection.

• Solar cell A has a refractive index of 3.1.
• Solar cell B has a refractive index of 1.3

Which solar cell will suffer the least from reflection losses?

Solar cell A

Solar cell B

Correct

That is correct

The reflection is calculated as

$R=\left( \frac{n_1-n_2}{ n_1+n_2} \right)^2$

where n1 is the index of refraction for air, while n2 is the index of refraction for the material in question.

1 / 1 point

3.Question 3

What type of bandgap would an optimum semiconductor material have for a solar cell?

A direct bandgap

An in-direct bandgap

It does not make any difference

Correct

That is correct

Ideally a semiconductor material for a solar cell should have a direct bandgap. A direct bandgap material allows a higher absorption coefficient, so thinner materials can be employed.