Efficient charge-transport in hybrid lead iodide perovskite solar cells.

Recently, highly efficient solar cells based on organic-inorganic perovskites have been intensively studied for developing fabricating methods and device structures. To improve the performance of perovskite film devices, delicate control of charge transfer material interconnectivity is required. Here, controlling the mesoporous TiO2 structure improves their charge collection and injection rate, and allows substantial enhancement of the corresponding device performance. We found that increasing the TiCl4 processing time deteriorates the device performance by introducing a large amount of excessively large perovskite particles, surface roughness and charge recombination. Proper TiCl4 processing dramatically improves the charge transport within the electron transfer layer, explaining the efficient performance of meso-superstructured solar cells.

Enhanced photocurrent by the co-sensitization of ZnO with dye and CuInSe nanocrystals.

ZnO nanocrystals with a particle size of 20-30 nm have been synthesised for the first time using a template-free method. Chalcopyrite Cu0.28In1.72Se2.72 nanocrystals (5-10 nm) were directly anchored on ZnO nanocrystals by a vacuum one-pot-nanocasting process without any long ligands. We further investigated Cu0.28In1.72Se2.72 quantum dots and dye bilayer-sensitized solar cells, which exhibited power conversion efficiency of 57.4% higher than the single-dye-sensitized solar cells.

Interface energy effect on the dispersion relation of nano-sized cylindrical piezoelectric/piezomagnetic composites.

Interface between the constituents plays an important role in the non-destructive detection of smart piezoelectric/piezomagnetic devices. The propagation of SH waves in nano-sized cylindrically multiferroic composites consisting of a piezoelectric layer and a piezomagnetic central cylinder is investigated, and the size-dependent dispersion relation with interface effect is derived. The general solutions of decoupled governing equation in different regions are expressed by using Bessel functions, and the unknown coefficients are determined by satisfying the boundary conditions at the inner interface with negligible thickness and the outer surface of the structure. Through the numerical examples of dispersion relation, it is found that the interface around the nano-cylinder may remarkably reduce the phase velocity, depending on the combination of the value of thickness ratio and the surface condition. The interface shows different effect on the first and second modes of dispersion relation.

Fundamental formulations and recent achievements in piezoelectric nano-structures: a review.

Piezoelectric nano-structures have been regarded as the next-generation piezoelectric material due to their inherent nano-sized piezoelectricity. This review summarizes the recent theoretical and experimental findings in piezoelectric nano-structures, including piezoelectric nanowires, nanoplates, nanobeams, nanofilms, nanoparticles, and piezoelectric heterogeneous materials containing piezoelectric nano-inhomogeneities. To begin, the types of piezoelectric nano-structured materials and the wide application of piezoelectric nano-structures in recent years are delineated. Next, the theoretical foundations including the definition of surface stress and electric displacement, the surface constitutive relations, the surface equilibrium equations, and nonlocal piezoelectricity, and their applications, are illustrated. Then, the effective mechanical and piezoelectric properties are depicted. Furthermore, the experimental investigations are classified, and some important observations are discussed. Finally, the perspectives and challenges for the future development of piezoelectric nano-structures are pointed out.