In nanoparticle group, we intend to fabricate various innovative “energy conversion materials” that work for forming a safe, healthy and sustainable society. Controlling the free-charge carriers generated in nanocrystals of high quality through the sequential absorption of photons at photoexcited conditions determines their optical properties and device performances of various applications including light emitting diodes, photodiodes, healthcare materials and biomarkers. To achieve it, we start our work from solution synthesis of various forms of inorganic nanocrystals, and take advantage of the quantum states that capture and release to energy storage and conversion to develop the cutting-edge materials in the fields of photonics, thermal phononics and optoelectronics.