What are the disadvantages of organic dyes in FRET?

Organic dyes are susceptible to photobleaching, where prolonged exposure to excitation light leads to irreversible loss of fluorescence signal. These dyes also exhibit poor photostability, and may have limited fluorescence lifetimes compared to alternative fluorophores such as fluorescent proteins or quantum dots. Fluorescence lifetimes of organic dyes typically range around 5 nanoseconds in visible light and 1 nanosecond in near-infrared wavelengths. Organic dyes may also still exhibit spectral overlap with neighboring fluorophores.