Question

The material used for solar cell should have band gap
(A) equal to zero.
(B) equal to \(0.08\) eV.
(C) between \(1.0\) eV to \(1.8\) eV.
(D) equal to \(2\) eV.

• A. D
• B. A
• C. C
• D. B

Hint:

Solar cell materials have band gaps close to the energy of visible light photons, between 1.0 and 1.8 eV.

Answer 1

The Correct Option is C

Step 1: Requirement:
A solar cell must absorb photons from sunlight, whose energy is mostly between about 1 eV and 3 eV. The band gap must be small enough for photons to excite electrons across, but large enough to give a useful voltage.

Step 2: Check the Statements:
(A) Zero band gap: this is a conductor, with no useful junction voltage.
(B) 0.08 eV: too small, so thermal energy alone would excite carriers.
(C) 1.0 to 1.8 eV: matches the visible and near infrared photon energies, as in silicon (1.1 eV) and GaAs (1.4 eV).
(D) 2 eV: too large, so much of the sunlight is not absorbed.

Step 3: Match the Choice:
Statement (C) is correct, which is option C of the question.

Final Answer:
The band gap should be between 1.0 eV and 1.8 eV, option C. \[ \boxed{\text{(C) between 1.0 eV and 1.8 eV}} \]