**Abstract**

BODIPY dyes are unique fluorophores that can be used in numerous application areas because of their interesting photophysical properties such as high molar absorptivity, tunable absorption and emission energies, and high fluorescence quantum yields. They show impressive photophysical property changes upon substitution of functional groups on the main core structure. Exchange of the meso-carbon on dipyrrin core with nitrogen produces an analog class of BODIPY called aza-BODIPY. Up to now, various kinds of BODIPY and aza-BODIPY derivatives have been developed and applied in science and industry. In this chapter, recent studies on photophysical properties of BODIPY derivatives are summarized.

**Keywords:** BODIPY, aza-BODIPY, fluorescence, fluorophore, photophysical property
