**4. Conclusion**

In this chapter, the basic photophysical properties of BODIPY and aza-BODIPY derivatives are introduced briefly. Unsubstituted BODIPY absorbs near 500 nm and emits around 510 nm. Substitution of amino- or alkoxy-moieties at the mesoposition of BODIPY core is expected to provide a shorter excitation and emission wavelength at the blue region with high quantum yields. Substitution of styryl- or distyryl moieties from 3,5-positions is expected to produce more red-shifted emissions. Aza-BODIPY derivatives also show red-shift in the absorption and emission profiles, because of the lone pair on the nitrogen. According to the recent advances on BODIPY dyes, it has seen that they have many application areas especially on bioimaging, laser-dyes, OPV devices, chemosensors, and PDT, because of their superior photophysics. It seems that BODIPY derivatives still will remain popular in the future.
