P-type nitrogen-doped ZnO nanoparticles stable under ambient conditions.

Zinc oxide is considered as a very promising material for optoelectronics. However, to date, the difficulty in producing stable p-type ZnO is a bottleneck, which hinders the advent of ZnO-based devices. In that context, nitrogen-doped zinc oxide receives much attention. However, numerous reviews report the controversial character of p-type conductivity in N-doped ZnO, and recent theoretical contributions explain that N-doping alone cannot lead to p-typeness in Zn-rich ZnO. We report here that the ammonolysis at low temperature of ZnO(2) yields pure wurtzite-type N-doped ZnO nanoparticles with an extraordinarily large amount of Zn vacancies (up to 20%). Electrochemical and transient spectroscopy studies demonstrate that these Zn-poor nanoparticles exhibit a p-type conductivity that is stable over more than 2 years under ambient conditions.

Synthesis of p-type transparent LaOCuS nanoparticles via soft chemistry.

We report here for the first time on the synthesis of nanoparticles of the p-type transparent conductor LaOCuS. Nanoparticles were obtained via a solvothermal route in ethylenediamine with dehydrated lanthanum chloride (LaCl(3).7H(2)O), copper monooxide, and elemental sulfur as precursors. Powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy ascertained our sample to be of high purity, while laser diffractometry evidenced a monodisperse particle size distribution centered on 126 nm. The absorption spectrum and the current-potential curves recorded under chopped illumination asserted the optical transparency and the p-type electronic conductivity of our LaOCuS nanoparticles.

Simple and reproducible procedure to prepare self-nanostructured NiO films for the fabrication of P-type dye-sensitized solar cells.

Porous and nanostructured thin films of NiO (3.5 microm thick) were prepared on FTO coated glass by annealing nickel acetate films obtained by recrystallization under hydrothermal conditions in the presence of hexamethylenetetramine. The photovoltaic performances of the NiO films were optimized with coumarin C343 as sensitizer and iodide/triodide as redox mediator and led to the following values of V(OC), J(SC), ff, and eta: 117 mV, 0.88 mA/cm(2), 0.28, and 0.036% respectively, under AM 1.5. With the improved PMI-NDI dyad as sensitizer and the tris(4,4'-bis(tertbutyl)bipyridine) cobalt(II/III) couple as redox mediator, the overall photoconversion efficiency reached 0.16%. An essential advantage of this procedure lies in its good reproducibility offering a reliable strategy to test new dyes and other parameters to improve the photoconversion efficiency of this new type of DSSC.