A photovoltaic cell contains a p–n junction that that converts solar light to electricity. An optimum semiconductor would have its band-gap energy matched to the wavelength of maximum solar intensity at the Earth's surface. (a) What is the color and approximate wavelength of maximum solar intensity at the Earth's surface? Refer to the figure for Problem 12.102.

Verified step by step guidance

1. Identify the concept of band-gap energy in semiconductors and its relation to the wavelength of light.
2. Understand that the wavelength of maximum solar intensity at the Earth's surface corresponds to the peak of the solar spectrum.
3. Recall that the visible spectrum ranges from approximately 400 nm (violet) to 700 nm (red).
4. Determine the color associated with the wavelength of maximum solar intensity by referring to the visible spectrum range.
5. Use the information about the solar spectrum to approximate the wavelength of maximum solar intensity and identify its corresponding color.

Key Concepts

Photovoltaic Cells

Photovoltaic cells, or solar cells, are devices that convert light energy directly into electrical energy through the photovoltaic effect. They typically consist of semiconductor materials, such as silicon, that create a p-n junction. When light photons strike the cell, they can excite electrons, generating a flow of electric current.

Band-Gap Energy

Band-gap energy is the energy difference between the valence band and the conduction band in a semiconductor. It determines the wavelengths of light that a semiconductor can absorb and convert into electrical energy. An optimal band-gap energy for a photovoltaic cell should align with the solar spectrum's peak intensity to maximize efficiency.

Solar Spectrum

The solar spectrum refers to the range of wavelengths of light emitted by the sun, which includes ultraviolet, visible, and infrared light. The maximum solar intensity at the Earth's surface occurs in the visible range, particularly around 500-600 nm, which corresponds to green light. Understanding the solar spectrum is crucial for designing effective photovoltaic materials.