Designed with semiconductors that have band gaps optimized to absorb the solar spectrum.
, it can kick an electron from the valence band to the conduction band, causing absorption.
): Determines the speed of light in the material and how much it "bends" (refraction). Extinction Coefficient ( Optical Properties of Solids
Since there is no gap, metals can absorb light at very low energies. However, above a certain frequency (the plasma frequency ), metals actually become transparent because the electrons can no longer keep up with the light's oscillation. 3. Key Optical Constants
To quantify these interactions, scientists use two main parameters: Refractive Index ( Designed with semiconductors that have band gaps optimized
Understanding these properties allows us to engineer materials for specific tasks:
Light bouncing off the surface. Metals are highly reflective because their "free" electrons can oscillate rapidly to cancel out the incoming field. Extinction Coefficient ( Since there is no gap,
): Represents how much light is lost to absorption as it travels through the solid. 4. Important Optical Phenomena