Energy level alignment at semiconductor-water interfaces from atomistic and continuum solvation models

Accurate and efficient methods for predicting the alignment between a semiconductor's electronic energy levels and electrochemical redox potentials are needed to facilitate the computational discovery of photoelectrode materials. In this paper, we present an approach that combines many-body perturbation theory within the GW method with continuum solvation models. Specifically, quasiparticle levels of the bulk photoelectrode are referenced to the outer electric potential of the electrolyte by calculating the change in electric potential across the photoelectrode-electrolyte and the electrolyte-vacuum interfaces using continuum solvation models. We use this method to compute absolute energy levels for the prototypical rutile (TiO2) photoelectrode in contact with an aqueous electrolyte and find good agreement with predictions from atomistic simulations based on molecular dynamics. Our analysis reveals qualitative and quantitative differences of the description of the interfacial charge density in atomistic and continuum solvation models and highlights the need for a consistent treatment of electrode-electrolyte and electrolyte-vacuum interfaces for the determination of accurate absolute energy levels.

为了促进光电极材料的计算发现，需要有准确且高效的方法来预测半导体的电子能级与电化学氧化还原电位之间的对齐情况。在本文中，我们提出了一种将GW方法中的多体微扰理论与连续介质溶剂化模型相结合的方法。具体而言，通过使用连续介质溶剂化模型计算光电极 - 电解质以及电解质 - 真空界面的电势变化，将块状光电极的准粒子能级参照电解质的外电势。我们使用这种方法计算与水性电解质接触的典型金红石（TiO₂）光电极的绝对能级，并发现与基于分子动力学的原子模拟预测结果吻合良好。我们的分析揭示了原子和连续介质溶剂化模型中界面电荷密度描述的定性和定量差异，并强调了为确定准确的绝对能级，需要对电极 - 电解质和电解质 - 真空界面进行一致处理。