You gotta check out Carbon Quantum Dots! I spent 3 hours last night on the wiki page reading all the referenced research papers and seeing what people are doing with them. It's nothing short of incredible!

I don't even know if I could TLDR but I'll try. The CQD's absorb a wavelength of light. Usually UV but capable of absorbing visible light at well and can convert that light to a specific wavelength or electrical energy and with various combinations of doping agents can tailor the CQD's to a specific application.

Some examples. 3D printed rocket fuel, cleaning up oil spills by breaking down the compounds. Optical applications. And a way to split water efficiently without major energy input. Very cool stuff.