In this study, the electrodeposition (ED) of ultrathin, compact TiO2 blocking layers (BLs) on fluorine-doped tin oxide (FTO) glass for perovskite solar cells (PSCs) is evaluated. This bottom-up method allows for controlling the morphology and thickness of TiO2 films by simply manipulating deposition conditions. Compared with BLs produced using the spin-coating (SC) method, BLs produced using ED exhibit satisfactory surface coverage, even with a film thickness of 29 nm. Evidence from cyclic voltammetry shows that an ED BL suppresses interfacial recombination more profoundly than an SC BL does, consequently improving the photovoltaic properties of the PSC significantly. A PSC equipped with an ED TiO2 BL having a 13.6% power conversion efficiency is demonstrated.

Crystal morphology and structure are important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electronic, and photovoltaic devices. In particular, crystal growth and dissolution are two major phenomena in determining the morphology of methylammonium lead iodide perovskite in the sequential deposition method for fabricating a perovskite solar cell. In this report, the effect of immersion time in the second step, i.e., methlyammonium iodide immersion in the morphological, structural, optical, and photovoltaic evolution, is extensively investigated. Supported by experimental evidence, a five-staged, time-dependent evolution of the morphology of methylammonium lead iodide perovskite crystals is established and is well connected to the photovoltaic performance. This result is beneficial for engineering optimal time for methylammonium iodide immersion and converging the solar cell performance in the sequential deposition route. Meanwhile, our result suggests that large, well-faceted methylammonium lead iodide perovskite single crystal may be incubated by solution process. This offers a low cost route for synthesizing perovskite single crystal.

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This paper conducts a multiscale parametric study of temperature and composition effects on the transport phenomenon of a solid oxide fuel cell (SOFC). The molecular dynamics technique was employed to study the transport phenomenon of the solid electrolyte, which is made of yttria-stabilized zirconia. The influences of Y2O3 concentration and various operation temperatures on the SOFC were studied. Simulation results show that there exists an optimal concentration of 8mol% of Y2O3 in the composition for oxygen transport. Also higher operation temperature promotes the oxygen ion-hopping process that increases the ionic conductivity. A macroscale parametric study was also conducted in this paper to validate the influence of the temperature uniformity in the solid electrolyte by employing the computational fluid dynamics technique. The temperature distribution maps of a single-cell planar SOFC with coflow, counterflow and cross-flow channel designs are presented. The results conclude that the coflow configuration is the best design of the three.