Kunzelmann Viktoria F, Jiang Chang-Ming, Ihrke Irina, Sirotti Elise, Rieth Tim, Henning Alex, Eichhorn Johanna, Sharp Ian D
Walter Schottky Institute and Physics Department, Technische Universität München Am Coulombwall 4 85748 Garching Germany
J Mater Chem A Mater. 2022 Apr 22;10(22):12026-12034. doi: 10.1039/d1ta10732a. eCollection 2022 Jun 7.
We demonstrate a facile approach to solution-based synthesis of wafer-scale epitaxial bismuth vanadate (BiVO) thin films by spin-coating on yttria-stabilized zirconia. Epitaxial growth proceeds solid-state transformation of initially formed polycrystalline films, driven by interface energy minimization. The (010)-oriented BiVO films are smooth and compact, possessing remarkably high structural quality across complete 2'' wafers. Optical absorption is characterized by a sharp onset with a low sub-band gap response, confirming that the structural order of the films results in correspondingly high optoelectronic quality. This combination of structural and optoelectronic quality enables measurements that reveal a strong optical anisotropy of BiVO, which leads to significantly increased in-plane optical constants near the fundamental band edge that are of particular importance for maximizing light harvesting in semiconductor photoanodes. Temperature-dependent transport measurements confirm a thermally activated hopping barrier of ∼570 meV, consistent with small electron polaron conduction. This simple approach for synthesis of high-quality epitaxial BiVO, without the need for complex deposition equipment, enables a broadly accessible materials base to accelerate research aimed at understanding and optimizing photoelectrochemical energy conversion mechanisms.
我们展示了一种简便的方法，通过在氧化钇稳定的氧化锆上旋涂，基于溶液合成晶圆级外延钒酸铋（BiVO）薄膜。外延生长通过界面能最小化驱动，由最初形成的多晶薄膜进行固态转变。（010）取向的BiVO薄膜光滑且致密，在整个2英寸晶圆上具有极高的结构质量。光吸收的特征是具有低子带隙响应的尖锐起始，证实了薄膜的结构有序性导致了相应的高光电子质量。结构和光电子质量的这种结合使得测量能够揭示BiVO的强光学各向异性，这导致在基频带边缘附近面内光学常数显著增加，这对于最大化半导体光阳极中的光捕获尤为重要。温度依赖的输运测量证实了约570 meV的热激活跳跃势垒，与小电子极化子传导一致。这种合成高质量外延BiVO的简单方法，无需复杂的沉积设备，为加速旨在理解和优化光电化学能量转换机制的研究提供了广泛可及的材料基础。
