Surface modification of semiconductor quantum dots (QDs) often causes a drastic reduction of photoluminescence quantum yield (QY). Here, we report an efficient way to improve photoluminescence (PL) characteristics of silica-coated QDs using the combination of light-induced PL enhancement (photoenhancement) and the small molecule reducing agent, dithiothreitol (DTT). The photoenhancement process in the absence of a reducing agent is usually accompanied by a blue shift and broadening of the PL spectrum as well as a subsequent rapid PL quenching due to the competitive photo-oxidation process. The addition of DTT augments the degree of photoenhancement and inhibits the spectral shift and broadening. The photoenhancement assisted by DTT reported here should provide a simple and useful means of preparing stable, highly luminescent water-soluble silica-coated QDs that have PL QYs comparable to those exhibited by organic-soluble QDs.

Stable ferroelectric (FE) phases in nanometer-thick films would enable ultra-high density and fast FE field effect transistors (FeFETs), and the stability of ferroelectricity in ultrathin films has been under intense theoretical and experimental investigation. Here we predict, using density functional theory calculations, that the low-energy epitaxial PbTiO3 (001)/Pt interface strengthens the electrode-oxide bonds by breaking in-plane symmetry and stabilizes a ground state with enhanced polarization in sub-nanometer oxide films, with no critical-size limit. Additionally, we show that such enhancement is related to large work function differences between the P − and P + PbTiO3 surfaces, which gives rise to a net polarizing field in the oxide.

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