Cadmium telluride is an important material for solar cells. (d) With respect to silicon, does CdTe absorb a larger or smaller portion of the solar spectrum?

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Understand the context: Cadmium telluride (CdTe) and silicon are both materials used in solar cells, and their ability to absorb sunlight is crucial for their efficiency.

Identify the band gap: The band gap of a material determines the range of the solar spectrum it can absorb. CdTe has a band gap of about 1.45 eV, while silicon has a band gap of about 1.1 eV.

Compare the band gaps: A larger band gap means the material absorbs higher energy (shorter wavelength) photons, while a smaller band gap allows absorption of lower energy (longer wavelength) photons.

Analyze the absorption: Since CdTe has a larger band gap than silicon, it absorbs a smaller portion of the solar spectrum, focusing more on higher energy photons.

Conclude the comparison: CdTe absorbs a smaller portion of the solar spectrum compared to silicon, which can absorb a broader range of wavelengths due to its smaller band gap.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Solar Spectrum Absorption

The solar spectrum encompasses all wavelengths of light emitted by the sun, ranging from ultraviolet to infrared. Different materials have varying abilities to absorb these wavelengths, which is crucial for their effectiveness in solar energy applications. Understanding how a material interacts with the solar spectrum helps determine its efficiency in converting sunlight into electricity.

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 material can absorb; materials with a smaller band gap can absorb lower-energy (longer wavelength) light. Cadmium telluride (CdTe) has a band gap of about 1.5 eV, which allows it to effectively absorb a significant portion of the solar spectrum compared to silicon.

Comparison of Semiconductor Materials

When comparing semiconductor materials like cadmium telluride (CdTe) and silicon, it is essential to consider their absorption coefficients and band gap energies. CdTe is known for its high absorption efficiency, meaning it can absorb more sunlight in a thinner layer compared to silicon. This characteristic makes CdTe a favorable choice for solar cells, especially in applications where material thickness and weight are critical.