Influence of Mg-doping on the characteristics of ZnO photoanodes in dye-sensitized solar cells.

Dye-sensitized solar cells (DSSCs) based on ZnO photoanodes have, despite extensive research, lagged behind cells based on TiO, which is due to generally lower open-circuit voltages V and fill factors. Here, DSSCs have been prepared using Mg-doped ZnO (MZO) photoanodes based on nanoparticles, thin films or ZnO-MZO core-shell-type nanoparticles with varying Mg-concentration. The cells were studied in detailed photoelectrochemical and photoluminescence experiments.

Transfer mechanisms in semiconductor hybrids with colloidal core/shell quantum dots on ZnSe substrates.

Hybrid systems consisting of colloidal CdS/ZnS core/shell quantum dots on ZnSe semiconductor substrates have been studied by continuous-wave and nanosecond time-resolved photoluminescence. On the basis of kinetic calculations, we studied the interplay between the possible transfer processes in these hybrids. The considered transfer mechanisms were resonance energy transfer, photon reabsorption, electron and hole tunneling.

Correlation of optical properties and interface morphology in type-II semiconductor heterostructures.

(Ga,In)As/GaAs/Ga(As,Sb) and (Ga,In)As/GaAs/Ga(N,As) type-II double quantum well heterostructures have been grown by metal-organic vapor phase epitaxy. A growth interruption procedure was used to intentionally modify the morphology of the internal interfaces. The heterostructures were investigated using continuous wave and time-resolved photoluminescence as well as optical pump-optical probe spectroscopy.

Interfacial Molecular Packing Determines Exciton Dynamics in Molecular Heterostructures: The Case of Pentacene-Perfluoropentacene.

The great majority of electronic and optoelectronic devices depend on interfaces between p-type and n-type semiconductors. Finding matching donor-acceptor systems in molecular semiconductors remains a challenging endeavor because structurally compatible molecules may not necessarily be suitable with respect to their optical and electronic properties, and the large exciton binding energy in these materials may favor bound electron-hole pairs rather than free carriers or charge transfer at an interface. Regardless, interfacial charge-transfer exciton states are commonly considered as an intermediate step to achieve exciton dissociation.

Magneto photoluminescence measurements of tungsten disulphide monolayers.

Layered transition-metal dichalcogenides have attracted great interest in the last few years. Thinned down to the monolayer limit they change from an indirect band structure to a direct band gap in the visible region. Due to the monolayer thickness the inversion symmetry of the crystal is broken and spin and valley are coupled to each other.