Semiconductors with complex anisotropic morphologies in solar to chemical energy conversion devices enhance light absorption and overcome limiting charge transport in the solid. However, structuring the solid–liquid interface also has implications for concentration distributions and diffusive charge transport in the electrolyte. Quantifying the link between morphology and those multi-physical transport processes remains a challenge. Here we develop a coupled experimental-numerical approach to digitalize the photoelectrodes by high resolution FIB-SEM tomography, quantitatively characterize their morphologies and calculate multi-physical transport processes for the exact geometries. We demonstrate the extraction of the specific surface, shape, orientation and dimension of the building blocks and the multi-scale pore features from the digital model. Local current densities at the solid–liquid interface and ion concentration distributions in the electrolyte have been computed by direct pore-level simulations. We have identified morphology-dependent parameters to link the incident-light-to-charge-transfer-rate-conversion to the material bulk properties. In the case of a structured lanthanum titanium oxynitride photoelectrode (E_g = 2.1 eV), with an absorbance of 77%, morphology-induced mass transport performance limitations have been found for low bulk ion concentrations and diffusion coefficients.

中文翻译：

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在结构化光电极中将形态与多物理输运联系起来†

太阳能到化学能转换装置中具有复杂各向异性形态的半导体可以增强光吸收，并克服固体中有限的电荷传输。但是，固液界面的结构也对电解质中的浓度分布和扩散电荷传输有影响。量化形态学与那些多物理输运过程之间的联系仍然是一个挑战。在这里，我们开发了一种耦合的实验-数值方法，通过高分辨率FIB-SEM断层扫描技术对光电极进行数字化处理，定量表征其形貌，并为精确的几何形状计算出多种物理传输过程。我们演示了从数字模型中提取构造块的比表面，形状，方向和尺寸以及多尺度孔特征的方法。固液界面的局部电流密度和电解质中的离子浓度分布已通过直接的孔隙水平模拟计算得出。我们已经确定了形态学相关的参数，以将入射光到电荷转移速率的转换与材料的整体性质联系起来。如果是结构化镧氧氮化钛光电极（E _g = 2.1 eV），吸光度为77％，对于低体积离子浓度和扩散系数，已经发现了由形态引起的传质性能极限。