Scattering and plasmonic synergetic enhancement of the performance of dye-sensitized solar cells by double-shell SiO2@Au@TiO2 microspheres.

The Au nanoparticle sandwich double spheric-shells of SiO2@Au@TiO2 (SAT) microspheres are synthesized. The significant influence of the SAT microspheres on the properties of dye-sensitized solar cells (DSSCs) is investigated. Studies indicate that the introduction of SAT markedly enhanced the light scattering and capture ability of DSSCs and thus photogenerated electrons. DSSCs doped with 2.25 wt% SAT exhibit a maximum short circuit current density of 17.0 mA cm-2 and photoelectric conversion efficiency of 7.14%, which are remarkably higher than those of conventional DSSCs at 15.7% and 21.2%, respectively. The marked enhancement in the performance of the optimal DSSCs can be attributed to the synergetic complementary effect of the enhanced light scattering of the microspheres and to the localized surface plasmon resonance of the Au nanoparticles in the SAT, and is a novel promising way of enhancing the performance of DSSCs.

Performance optimization of dye-sensitized solar cells by multilayer gradient scattering architecture of TiO2 microspheres.

TiO2 microspheres (TMSs) with unique hierarchical structure and unusual high specific surface area are synthesized and incorporated into a photoanode in various TMS multilayer gradient architectures to form novel photoanodes and dye-sensitized solar cells (DSSCs). Significant influences of these architectures on the photoelectric properties of DSSCs are obtained. The DSSC with the optimal TMS gradient-ascent architecture of M036 has the largest amounts of dye absorption, strongest light absorption, longest electron lifetime and lowest electron recombination, and thus exhibits the maximum short circuit current density (Jsc) of 16.49 mA cm-2 and photoelectric conversion efficiency (η) of 7.01%, notably higher than those of conventional DSSCs by 21% and 22%, respectively. These notable improvements in the properties of DSSCs can be attributed to the TMS gradient-ascent architecture of M036 which can most effectively increase dye absorption and localize incident light within the photoanode by the light scattering of TMSs, and thus utilize the incident light thoroughly. This study provides an optimized and universal configuration for the scattering microspheres incorporated in the hybrid photoanode, which can significantly improve the performance of DSSCs.

Plasmonic-resonance-based ternary composite complementary enhancement of the performance of dye-sensitized solar cells.

Graphene (G), TiO2 fusiform nanorods (TiO2NRs) adsorbed with Au nanoparticles (AuNPs) are prepared and blended as multifunctional materials into TiO2 nanocrystalline film to form a novel ternary (G-TiO2NRs-Au) composite photoanode in dye-sensitized solar cells (DSSCs). The effects of G-TiO2NRs-Au on the properties of the photoanode and DSSC are investigated. Results show that, by blending G-TiO2NRs-Au, the light absorption and scattering of the photoanode are obviously improved, and the charge transfer resistance R2 and electron recombination are decreased, resulting in a significant enhancement in the short-circuit current density (J sc) and the photoelectric conversion efficiency (PCE) of the DSSCs. The maximum J sc of 17.66 mA cm(-2) and PCE of 8.56% are obtained in the optimal G-TiO2NRs-Au-based DSSC, about 33.6% and 35.0% higher than that obtained in the conventional TiO2-based DSSC. This significant improvement in the performance of the DSSC can be attributed to the ternary composite complementary effects of multi-functions from the surface plasmon resonance of AuNPs, light scattering of TiO2NRs, and the improved dye loading and fast electron transmission channel from graphene. This study provides an effective way of ternary composite complementary enhancement of the J sc and PCE of the DSSCs.

Nanointerlayer induced electroluminescence transition from ultraviolet- to red-dominant mode for n-Mn:ZnO/N-GaN heterojunction.

High-quality Mn:ZnO (MZO) film had been prepared on N-GaN coated sapphire substrates followed by postdeposition thermal annealing treatment at 700 °C. For the annealed MZO/GaN heterojunction, a 15 nm cubic structural ZnGa(2)O(4) layer was observed at the MZO/GaN interface through transmission electron microscope analysis. Through electroluminescence (EL) measurement, the formation of the nanointerface results in an EL transition from ultraviolet- to red-dominant mode for n-Mn:ZnO/N-GaN heterojunction light-emitting diodes (LEDs). The heterojunction LED showed a rectification ratio of ∼2.0 × 10(5) at ±2 V, a dark current of 3.5 nA at -2 V and a quite strong red EL with a low turn-on voltage of 3 V. On the basis of the energy band diagram, we think the EL transition from ultraviolet- to red-dominant mode is mainly due to the formation of a thin oxide blocking nanolayer at the MZO/GaN interface during the annealing process.