Black Phosphorus Based Photocathodes in Wideband Bifacial Dye-Sensitized Solar Cells.

Ultrasmall black phosphorus quantum dots (BPQDs) serve as the near-infrared light absorber and charge transfer layer in the photocathode of a bifacial n-type dye sensitized solar cell. Wideband light absorption and ≈20% enhancement in the light-to-electron efficiency are accomplished due to the fast carrier transfer and complementary light absorption by the BPQDs demonstrating that BP has large potential in photovoltaics.

Competitive reaction pathway for site-selective conjugation of Raman dyes to hotspots on gold nanorods for greatly enhanced SERS performance.

Common methods to prepare SERS (surface-enhanced Raman scattering) probes rely on random conjugation of Raman dyes onto metal nanostructures, but most of the Raman dyes are not located at Raman-intense electromagnetic hotspots thus not contributing to SERS enhancement substantially. Herein, a competitive reaction between transverse gold overgrowth and dye conjugation is described to achieve site selective conjugation of Raman dyes to the hotspots (ends) on gold nanorods (GNRs). The preferential overgrowth on the nanorod side surface creates a barrier to prevent the Raman dyes from binding to the side surface except the ends of the GNRs, where the highest SERS enhancement factors are expected. The SERS enhancement observed from this special structure is dozens of times larger than that from conjugates synthesized by conventional methods. This simple and powerful strategy to prepare SERS probes can be extended to different anisotropic metal nanostructures with electromagnetic hotspots and has immense potential in in-depth SERS-based biological imaging and single-molecule detection.