Bandgap Tuning of High Mobility Magnetron Sputtered Copper (I) Oxide Thin Films for Perovskite Solar Cell Applications

We report on the successful growth optimization of an inorganic p-type copper oxide (Cu2O) thin films for various energy applications. First, Cu2O thin films of a typical thickness of 100 nm are deposited on fluorine-doped tin oxide (FTO) coated glass substrates by DC-reactive magnetron sputtering, followed by their in-depth characterization with different techniques, including scanning electron and atomic force microscopies, UV-Vis, X-ray diffraction and photoelectron spectroscopies, to probe their structural, optical, and morphological properties. Surface topology analysis revealed homogeneous, compact, and uniform sputtered deposited films. The as deposited films layers have shown a preferential crystal orientation of (111) and a stoichiometry of CuO, at the surface, which is believed to be mainly due to the oxidization effect of the non-capsulated surface, while a short-duration argon etching (~ 5 s) has revealed the growth of Cu2O films stoichiometry. Finally, during the reactive plasma deposition, films were grown under nitrogen gas flow to improve their hole-mobility, followed by a systematic annealing at various temperatures ranging from 100 to 250 °C to improve their crystalline structure. Hall effect measurement confirmed that the Cu2O thin film are p-type, with extremely high electronic properties, including an electrical conductivity of 2.6 × 102 S/cm, a hole mobility of about 30 cm2/Vs and a charge carrier density around 5 × 1019 cm-3, making them a serious candidate for a hole transport layer in perovskite solar cells.

Reproducible Electrodeposition of Hydrogen Molybdenum Bronze Films and Electrochemical Reduction of Carbon Dioxide

Electrochemical synthesis of hydrogen bronze films including molybdenum, tungsten and vanadium are useful electrocatalytic films. This paper describes reproducible hydrogen molybdenum bronze film formation on indium tin oxide and carbon paper substrates by electrodeposition. Film formation is a kinetic process dependent on concentration, time and potential. Bulk electrolysis over time determined the dependence of film thickness on time of deposition. Once the films were prepared, the films were characterized by thickness, conductivity, XPS and X-Ray Diffraction. Cyclic voltammetry in dilute sulfuric acid confirmed that these films are not electrochromic. Hydrogen bronze films on conductive carbon paper were also prepared. Carbon dioxide bubbled into 0.5 M NaHCO3 using a hydrogen bronze film as the working electrode resulted in formate quantified by ion chromatography. Cyclic voltammetry and Tafel plots using the as deposited films in 0.5 M NaHCO3 saturated with CO2 showed catalytic activity toward reduction of carbon dioxide. A Farradaic efficiency of 8% was obtained with an applied potential of -0.4 V.

A Theoretical Design of a New Organic Dye Containing Coronene for Dye-Sensitized Solar Cells

In search of novel high-performance materials for use in dye-sensitized solar cells (DSSCs), we used density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to study the geometry, electronic, and optical properties, for organic molecules. The enhancement of organic dye was done by the terminal addition with organic molecule in order to improve their electronic properties and optical absorption. The absorption is became higher than that of the original dye where the rising absorption from 1050 to 1350 approximately. Also, we found that the B3LYP functional with the 6-31G basis set gave highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. The energy gap decreased after addition from 2.73 to 2.52 eV.