**2.5 Nanoscale confinement of electronic interactions**

This section focuses on a few basic examples of nanoscale electronic interactions that cause drastic changes in the optical properties of a material. The results of confining electronic interactions at the nanoscale involve a variety of factors that control them, which are discussed below.

## *2.5.1 Quantum confinement effects*

Quantum confinement alters the optical properties of semiconductors in a number of ways, and these variations have practical applications. As a semiconductor's length is limited to a similar order of exciton radius, i.e. a few nanometers, hence the quantum confinement effect happens. The dimensionality of electrons is reduced by confining them to a thin semiconductor surface, resulting in a dramatic increase in exciton properties and behavior. QuantumDots, Quantum Wires, and Quantum Wells are the three kinds of quantum confined structures that have been described so far based on the function of confinement [6]. The optical transformations caused by different confinements are mentioned in **Table 3**.

### *2.5.2 Quantum-confined stark effect*

The quantum-confined stark effect explains how an applied electric field affects energy levels and thus optical spectra. Quantum-confined devices exhibit major

**Table 3.**

*Optical transition under the effect of quantum confinement of electrons at nanoscale.*

variations in their optical spectra where an electric field is applied in the direction of confinement [6]. The most important embodiments of quantum confinement effects are mentioned in the **Table 4**.
