Identifying Lanthanide Energy Levels in Semiconductor Nanoparticles Enables Tailored Multicolor Emission through Rational Dopant Combinations

The unique photon emission signatures of trivalent lanthanide cations (Ln³⁺, where Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) enables multicolor emission from semiconductor nanoparticles (NPs) either through doping multiple Ln³⁺ ions of distinct identities or in combination with other elements for the creation of next-generation light emitting diodes (LEDs), lasers, sensors, imaging probes, and other optoelectronic devices. Although advancements have been made in synthetic strategies to dope Ln³⁺ in semiconductor NPs, the dopant(s) selection criteria have hinged largely on trial-and-error. This combinatorial approach is often guided by treating NP–dopant(s) energy transfer dynamics through the lens of spectral overlap. Over the past decade, however, we have demonstrated that the spectral outcomes correlate better with the placement of Ln³⁺ energy levels with respect to the band edges of the semiconductor, and oxide, host.