2017 Volume 85 Issue 9 Pages 543-551
This paper reviews my recent investigations on fluorescent semiconductor nanoparticles based on the observation of photoluminescence quenching caused by photoinduced electron transfer to surrounding molecules. Semiconductor nanoparticles having photoluminescence at room temperature were quenched intentionally by the addition of redox species. The magnitude of quenching was greatly varied according to the interaction between the nanoparticles and quenchers, redox potential of quenchers, and the states of surface ligands protecting the semiconductor nanoparticles. The study began from the basic investigations on factors determining the magnitude of quenching and several material sensing systems were proposed as output of research. The phenomenon was then used to investigate the condition of surface ligands by using the strong distance dependence of the photoinduced electron transfer efficiency. Quantitative analyses of quenching revealed the differences in protection ability between the types of ligands. In the last part of this paper, I mention the possibility of semiconductor nanoparticles as practical fluorescence materials. The precise control of the distance between the nanoparticles realized emission from condensed nanoparticles with photoluminescence quantum yield over 80%.
