The functionality of oxide pervoskites including SrTiO3 and BaTiO3 in bulk samples has been well-studied and is sensitive to the presence of extrinsic dopants and intrinsic defect chemistry of the perovskite. The unique defect chemistry of freestanding nanocrystal (NC) analogues have received much less attention in comparison. We employ electron paramagnetic resonance and photoluminescence spectroscopies to interrogate the defect chemistry of undoped SrTiO3 colloidal NCs as well as both aliovalent and isovalent substitutional transition metal dopants. We observe clear spectral signatures of surface-related oxygen vacancies in the undoped SrTiO3 colloidal NCs that can be controlled during hydrothermal growth. In addition, the speciation and correlated introduction of charge-compensating defects in Cr3+-doped SrTiO3 colloidal NCs is presented and discussed. We introduce Ti3+ defects through photodoping the SrTiO3 colloidal NCs and observe drastic changes to the spin dynamics of substitutional and isoelectronic dopants Cr3+ and Mn4+. These findings demonstrate that the electronic structures of dopant ions are clearly mediated by partially delocalized, but spatially confined, lattice defects. Our observations in these photodoped NCs will be compared and contrasted to similar phenomena observed in chemically-reduced bulk analogues.

Controlling dopant-defect interactions in doped SrTiO3 colloidal nanocrystals

253rd National Meeting (2017)

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