Doping nanocrystals to manipulate their optical properties

For decades, the size-dependent optical properties of semiconductor nanocrystals have been explored to elucidate their fundamental electronic nature and develop their potential for optoelectronic devices. Recently, substitutional doping has emerged as a complementary strategy by which new optical characteristics can be introduced to colloidal nanocrystals. I will describe two classes of doped nanocrystals with distinctive optical properties. Nanocrystals doped with combinations of lanthanide ions can emit visible light following absorption of multiple IR photons. This upconversion process occurs by way of energy transfer between nearby ions. Meanwhile, semiconductor nanocrystals doped degenerately with heterovalent ions can exhibit plasmon resonance absorption tunable across the mid- and near-IR.