Comparison studies of excitonic properties and multiphoton absorption of near-infrared-I-emitting Cu-doped InP and InP/ZnSe nanocrystals

Cu-doped InP (Cu:InP) and InP/ZnSe nanocrystals (NCs) with near-infrared-I (NIR-I) emission were prepared and characterized. Femtosecond transient absorption spectra revealed that the epitaxial growth of a ZnSe diffusion barrier onto the Cu:InP core can amplify its exciton-dopant coupling strength, with the energy transfer times of ∼ 220 p s for Cu:InP NCs and ∼ 183 p s for Cu:InP/ZnSe NCs. Importantly, the Cu:InP/ZnSe NCs exhibit much larger two- and three-photon absorption cross sections, reaching ∼ 10162 GM at 1030 nm and ∼ 1.06 × 10 − 77 c m 6 s 2 p h o t o n − 2 at 1600 nm, compared with Cu:InP NCs.