How do optoelectronic materials interact with both electrons and photons?

Optoelectronic materials, typically semiconductors, interact with electrons and photons by facilitating the conversion between electrical energy and light radiation. This interaction is primarily governed by the material's bandgap, which determines the energy required to move an electron from the valence band to the conduction band.1

Light to Electricity

When photons with sufficient energy strike a semiconductor, they can excite electrons into the conduction band, creating "hole-electron pairs." In devices like solar cells, a p-n junction separates these charges, generating a voltage and producing an electric current. This process is also the basis for photoconductivity, where illumination increases the material's electrical conductivity.21

Electricity to Light

Conversely, when an electric current is applied, electrons can be injected into the material. As these electrons drop into holes in the valence band, they release energy equal to the bandgap. In materials like gallium arsenide, this energy is emitted as photons, a process known as electroluminescence. This principle powers light-emitting diodes (LEDs) and semiconductor lasers.32