Luo Yanhong

Enhanced Performance in Perovskite Organic Lead Iodide Heterojunction Solar Cells with Metal-Insulator-Semiconductor Back Contact

Metal-insulator-semiconductor back contact has been employed for a perovskite organic lead iodide heterojunction solar cell, in which an ultrathin Al2O3 film as an insulating layer was deposited onto the CH3NH3PbI3 by atomic layer deposition technology. The light-to-electricity conversion efficiency of the devices is significantly enhanced from 3.30% to 5.07%. Further the impedance spectrum reveals that this insulating layer sustains part of the positive bias applied in the absorber region close to the back contact and decreases the carrier transport barrier, thus promoting transportation of carriers.

Efficiency enhancement of dye-sensitized solar cells: Using salt CuI as an additive in an ionic liquid

Energy conversion efficiency of the dye-sensitized solar cell is improved from 3.5% to 4.5% by adding a small amount of CuI into an ionic liquid electrolyte. It is found that other copper-I salts, for example, CuBr, have the same effect for the dye-sensitized solar cell. Experimental results show that no Cu2+ ions exist in this electrolyte. It is suggested that this improvement is caused by the adsorption of Cu+ onto the TiO2 porous film.

Suppressing Charge Recombination in ZnO-Nanorod-Based Perovskite Solar Cells with Atomic-Layer-Deposition TiO2*

ZnO nanorods are passivated with a TiO2 interfacial layer prepared by the atomic layer deposition method and applied in the CH3NH3PbI3 perovskite solar cell, which show a positive effect on the fill factor and power conversion efficiency. With TiO2 interfacial passivation, the charge recombination in the ZnO/CH3NH3PbI3 interface is effectively suppressed and the maximum power conversion efficiency is enhanced from 11.9% to 13.4%.

A New Method for Generating Hydrogen from Water

A new method for generating hydrogen by the reaction of Al powder with water using iodine as additive is developed. I2 can penetrate through the surface oxide layer on aluminium to form AlI3. High solubility of AlI3 in water is benefited to activate Al surface. It is found that the production of hydrogen becomes significant above 60° C and obeys a logarithm rule. The pH value varies from 5 to 3 then back to 4.5 during the reaction, which is determined mainly by the kinetics of hydration reaction of AlI3 and the reaction of Al and HI produced spontaneously.

Real-time quantitative optical method to study temperature dependence of crack propagation process in colloidal photonic crystal film

A real-time quantitative optical method to characterize crack propagation in colloidal photonic crystal film (CPCF) is developed based on particle deformation models and previous real-time crack observations. The crack propagation process and temperature dependence of the crack propagation rate in CPCF are investigated. By this method, the crack propagation rate is found to slow down gradually to zero when cracks become more numerous and dense. Meanwhile, with the temperature increasing, the crack propagation rate constant decreases. The negative temperature dependence of the crack propagation rate is due to the increase of van der Waals attraction, which finally results in the decrease of resultant force. The findings provide new insight into the crack propagation process in CPCF.