What about Quantum Dots?
Let’s start with a quick refresher. Quantum dots are cool
little tiny nano particles, less than 10 nm in diameter, made of a semiconductor alloy core and coated with a shell of a different alloy, which fluoresce at different wavelengths depending on their size and specific composition. The smaller the quantum dot, the more blue-shifted its emission wavelength while larger quantum dots (6 nm and larger) shift to red and near-IR. Quantum dots can be a good alternative to organic dyes since they have broad excitation spectra (absorb energy at a wide range of wavelengths), narrow emission spectra (emit a fairly specific wavelength), and don’t suffer from photobleaching (degradation due to light intensity/oxidizing agents). Read more about fluorescence excitation and emission.