Ni-Doped SnO2 as an Electron Transport Layer by a Low-Temperature Process in Planar Perovskite Solar Cells.

Perovskite solar cells (PSCs) based on a planar structure have recently become more attractive due to their simple manufacturing process and relatively low cost, while most perovskite solar cells employ highly porous TiO2 as an electron transport layer in mesoporous devices offering higher energy conversion efficiency (PCE). In planar structural devices, non-radiative recombination effects of the absorber layer and the electron transport layer cause potential loss and lower PCE. We created an efficient electron transport layer by combining low-temperature Ni-doped SnO2 with SDBS as a surfactant (denoted as Ni:SnO2). Doping Ni+ into low-temperature solution-processed SnO2 increased the power conversion efficiency of PSCs from 17.8 to 19.7%.

Reduced Defects and Enhanced Performance of (FAPbI3)0.97(MAPbBr3)0.03-Based Perovskite Solar Cells by Trimesic Acid Additives.

A high-quality organolead trihalide perovskite film with large-sized crystalline grains and smooth surfaces is required to obtain efficient perovskite solar cells (PSCs). Herein, high-quality (FAPbI3)0.97(MAPbBr3)0.03 perovskite films were fabricated using trimesic acid (TMA) additives in a halide perovskite precursor solution to obtain efficient PSCs. The X-ray diffraction analysis and scanning electron microscopy of the films revealed that the TMA had a significant effect on the roughness of the films by acting as a surface link, thus reducing the surface defects and recombination at the grain boundaries. In addition, with the addition of the TMA additive, a smooth perovskite film with a flat surface and no pinholes was obtained. The perovskite film was used to fabricate a PSC device, and the device exhibited a high power conversion efficiency of 17.26%, which was higher than that of the control device (15.15%) under the same conditions. This study demonstrates a facile method to passivate defects on the perovskite layer via surface modification.

Probing surface and bulk electrochemical processes on the LaAlO3-SrTiO3 interface.

Local electrochemical phenomena on the surfaces of the LaAlO(3)-SrTiO(3) heterostructure are explored using unipolar and bipolar dynamic electrochemical strain microscopy (D-ESM). The D-ESM suggests the presence of at least two distinct electrochemical processes, including fast reversible low-voltage process and slow high-voltage process. The latter process is associated with static surface deformations in the sub-nanometer regime. These behaviors are compared with Kelvin probe force microscopy hysteresis data. The possible origins of observed phenomena are discussed, and these studies suggest that charge-writing behavior in LAO-STO includes a strong surface/bulk electrochemical component and is more complicated than simple screening by surface adsorbates.

Thick lead-free ferroelectric films with high Curie temperatures through nanocomposite-induced strain.

Ferroelectric materials are used in applications ranging from energy harvesting to high-power electronic transducers. However, industry-standard ferroelectric materials contain lead, which is toxic and environmentally unfriendly. The preferred alternative, BaTiO(3), is non-toxic and has excellent ferroelectric properties, but its Curie temperature of ∼130 °C is too low to be practical. Strain has been used to enhance the Curie temperature of BaTiO(3) (ref. 4) and SrTiO(3) (ref. 5) films, but only for thicknesses of tens of nanometres, which is not thick enough for many device applications. Here, we increase the Curie temperature of micrometre-thick films of BaTiO(3) to at least 330 °C, and the tetragonal-to-cubic structural transition temperature to beyond 800 °C, by interspersing stiff, self-assembled vertical columns of Sm(2)O(3) throughout the film thickness. The columns, which are 10 nm in diameter, strain the BaTiO(3) matrix by 2.35%, forcing it to maintain its tetragonal structure and resulting in the highest BaTiO(3) transition temperatures so far.