Question:medium

The material used for solar cell should have band gap ______.

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Band Gap Cheat Sheet:
Conductors = 0 eV
Solar Cells = 1.0 to 1.8 eV (Matches visible light photons!)
LEDs (Visible) = 1.8 to 3.0 eV
Insulators = > 3.0 eV
Updated On: Jun 19, 2026
  • equal to zero.
  • less than 1.0 eV (non-zero).
  • more than 1.8 eV.
  • between 1.0 eV and 1.8 eV.
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The Correct Option is D

Solution and Explanation

Step 1: Understanding the Concept:
A solar cell works by the photovoltaic effect. For maximum efficiency, the semiconductor's band gap ($E_g$) should match the solar spectrum peak.

Step 2: Formula Application:

Efficiency is highest when $E_g \approx 1.4$ eV (Shockley-Queisser limit).

Step 3: Explanation:

- If $E_g$ is too small, the output voltage is low. - If $E_g$ is too large (e.g., $> 1.8$ eV), most solar photons won't have enough energy to create electron-hole pairs. - Silicon ($1.1$ eV) and GaAs ($1.4$ eV) fall in the ideal $1.0$ to $1.8$ eV range.

Step 4: Final Answer:

The band gap should be between 1.0 eV and 1.8 eV.
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