Improved performance of perovskite solar cells through using (FA)x(MA)1-xPbI3 optical absorber layer

In this work, the perovskite solar cells (PSCs) were fabricated with the bandgap-tunable (FA)x(MA)1-xPbI3 absorber layers through a facile two-stage deposition route. The doping was realized by adding the formamidinium iodide (FAI) into a precursor MAI solution. Both the surface morphology and electrochemical impedance spectra (EIS) were conducted to evaluate the absorber layers or solar cells. After the optimization, the best PSC performance of 14.73% was achieved at a nominal FAI content of 12.5 at.%. The performance enhancement was attributed to both the enhancement of visible light harvesting and carrier transport capability. Besides, the stability of a PSC device based on the single MAPbI3 absorber layer was also investigated, and a power conversion efficiency (PCE) of 11.27 % remained even after laying in vacuum for 10 days.     

Effect of growth time on morphology and photoelectrochemical performance of TiO2 nanorod arrays grown on transparent conducting substrates

TiO2 nanorod arrays (NRAs) were synthesized directly on the fluorine tin oxide (FTO) coated glass substrates by a facile hydrothermal route. The effects of growth time on the photoelectrochemical (PEC) properties of TiO2 NRAs are investigated. The samples synthesized for 4 h exhibit a photocurrent intensity of 0.37 mA/cm2 at the irradiation of Xe lamp and a bias of 0 V. As the growth time increases, the thickness and order degree of the NRAs are enhanced, but the photocurrent is reduced a lot. It might be associated with the hindering of a high background electron density in NRs due to the long-time hydrothermal reaction in acid environment. Moreover, the decline behavior is observed, which is attributed to the poor charge separation capacity of TiO2 array electrodes and could be suppressed efficiently by applying a suitable positive bias.     

Improved photoelectrochemical performance by forming a ZnO/ZnS core/shell nanorod array

ZnO nanorod arrays (NRAs) were prepared via a facile hydrothermal method for photoelectrochemical (PEC) applications. Then, ZnS thin shell layers were deposited onto them via a facile hydrothermal treatment process for constructing a ZnO/ZnS core/shell structure. It was demonstrated that the PEC activity of a ZnO NRA is enhanced significantly after the surface modification, although there weren’t any obvious changes in the visible-light harvesting efficiency. Both the Nyquist and Mott-Schottky (M-S) plots were employed to reveal the reason, which was attributed to higher electrocatalytic activity of ZnS than that of ZnO and the resulting higher charge transfer efficiency across the solid/liquid interfaces. Finally, a schematic band model was proposed for clarifying the charge carrier transfer mechanism occurred at the interfaces.     

Photoelectrochemical characteristics of TiO2 nanorod arrays grown on fluorine doped tin oxide substrates by the facile seeding layer assisted hydrothermal method

TiO2 nanorod arrays (NRAs) were prepared on fluorine doped tin oxide (FTO) substrates by a facile two-step hydrothermal method. The nanorods were selectively grown on the FTO regions which were covered with TiO2 seeding layer. It took 5 h to obtain the compact arrays with the nanorod length of ~2 μm and diameter of ~50 nm. The photoelectrochemical (PEC) properties of TiO2 NRAs are also investigated. It is demonstrated that the TiO2 NRAs indicate the good photoelectric conversion ability with an efficiency of 0.22% at a full-wavelength irradiation. A photocurrent density of 0.21 mA/cm2 is observed at 0.7 V versus the saturated calomel electrode (SCE). More evidences suggest that the charge transferring resistance is lowered at an irradiation, while the flat-band potential (Vfb) is shifted towards the positive side.     

Influence of annealing temperature on visible-light photocatalytic activities of Ag3PO4 particulates synthesized using CH3COOAg as a precursor

Ag3PO4 microparticles (MPs) were prepared through a facile chemical precipitation route and using silver acetate (AgAc) as metal salt. The effect of annealing temperature (Ta) and time (τa) on the actual photocatalytic (PC) activity of Ag3PO4 MPs is investigated. The optimal annealing parameters are Ta of 400 °C and τa of 90 min. The enhanced PC activity by annealing at 400 °C is ascribed to the increase of electron mobility. Besides, an Ag3PO4 photoelectrode was fabricated through a drop-coating deposition route, which demonstrates a photocurrent density of 80 μA/cm2 and acceptable stability. The n-type conduction behavior of Ag3PO4 is verified by a Mott-Schottky (M-S) plot.     

磷酸银应用于太阳能光催化的研究进展

主要回顾了近年来有关Ag3PO4合成与表征方面的研究进展。通过较全面的综述,使人们对该材料的发展现状有了较为直观的认识。首先,介绍了光催化剂的工作原理、类型、应用以及发展态势等。总结并分析了国内外在Ag3PO4领域较为活跃的研究小组的最新研究成果。其次,简单介绍了Ag3PO4光催化剂的主要合成方法,并比较了这些方法的优劣。最后,展望了Ag3PO4的应用前景,并分析了当前研究中尚待解决的一些问题。并针对其提出了一些改进措施,包括在合成过程中添加表面活性剂以提高产物的比表面积、对产物进行表面包覆以增强稳定性或与TiO2复合以降低成本等。