Complex metal oxide semiconductors are promising candidates to be used as photoelectrodes in solar water splitting devices. One particular example is copper bismuth oxide (CuBi2O4), which is a p-type semiconductor with an ideal bandgap of 1.6–1.8 eV and suitable band positions. However, the performance has been reported to be limited by photocorrosion and the mismatch between its optical absorption and charge carrier transport properties. It has been shown that the former can be overcome by the deposition of protection layers, while the latter can be addressed by the modification of the bulk properties of the material. Here, we deposited thin films of CuBi2O4 using pulsed laser deposition (PLD). This results in high quality films, as evident from the internal quantum efficiency, which is comparable to the best-performing CuBi2O4 photoelectrodes. We investigate the bulk modification of the films by exploring post-deposition annealing treatment at various temperatures and oxygen partial pressures. These post-deposition annealing parameters influence the morphology of the films through the formation of aggregated particles/islands with higher crystallinity. The anneal treatment reduces bulk recombination in the film and increases the AM1.5 photocurrent by a factor of more than three. The influence of the high temperature post-deposition annealing treatment on other properties of CuBi2O4 (absorption, formation, and suppression of defects) is also discussed. This study underlines the importance of high temperature post-deposition annealing treatment in optimizing the performance of complex metal oxide photoelectrodes.

中文翻译：

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沉积后退火对CuBi2O4薄膜光电化学性能的影响

复合金属氧化物半导体有望用作太阳能水分解装置中的光电极。一个特殊的例子是氧化铜铋 (CuBi2O4)，它是一种 p 型半导体，具有 1.6-1.8 eV 的理想带隙和合适的带位置。然而，据报道，性能受到光腐蚀及其光吸收和电荷载流子传输特性之间的不匹配的限制。已经表明，前者可以通过保护层的沉积来克服，而后者可以通过修改材料的整体特性来解决。在这里，我们使用脉冲激光沉积 (PLD) 沉积了 CuBi2O4 薄膜。这产生了高质量的薄膜，从内部量子效率可以看出，这与性能最好的 CuBi2O4 光电极相当。我们通过探索不同温度和氧分压下的沉积后退火处理来研究薄膜的整体改性。这些沉积后退火参数通过形成具有更高结晶度的聚集颗粒/岛来影响薄膜的形态。退火处理减少了薄膜中的体复合，并将 AM1.5 光电流增加了三倍以上。还讨论了高温沉积后退火处理对 CuBi2O4 其他性能（缺陷的吸收、形成和抑制）的影响。该研究强调了高温沉积后退火处理在优化复合金属氧化物光电极性能方面的重要性。