Pentacene and tetracene molecules and films on H/Si(111): level alignment from hybrid density functional theory
Pentacene and tetracene molecules and films on H/Si(111): level alignment from hybrid density functional theory
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DOI：
10.1088/2516-1075/ab9bb5
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发表时间：
2020-09-01
影响因子：
2.6
通讯作者：
Blum, Volker
中科院分区：
文献类型：
--
作者：
Janke, Svenja M.;Rossi, Mariana;Blum, Volker
杂化有机-无机半导体界面的电子性质强烈依赖于有机/无机组分中电子载流子能级的排列。在目前的工作中，我们从第一性原理理论的两个典型的有机-无机半导体界面，单重态裂变材料并四苯和并五苯的H/Si（111），使用全电子密度泛函理论计算的混合交换相关功能。对于H/Si（111）上的孤立的并四苯，发现了类I型异质结（Si上的最低能量电子和空穴态），对于孤立的并五苯，分子和半导体的价带边是简并的。对于单层膜，我们展示了如何构建超晶胞几何形状与多达1192个原子，最大限度地减少无机表面和有机单层膜之间的应变。基于这些模型，我们预测形成的II型异质结（Si上的电子态，空穴状的状态上的有机物种）的并苯，表明在有机和无机成分之间的界面处的电荷分离是有利的。本文讨论了从第一性原理中找到合适的低能界面几何结构的弱键合有机分子和无机衬底上的膜所需的步骤，这是任何计算水平对齐预测的必要先决条件。
The electronic properties of hybrid organic-inorganic semiconductor interfaces depend strongly on the alignment of the electronic carrier levels in the organic/inorganic components. In the present work, we address this energy level alignment from first principles theory for two paradigmatic organic-inorganic semiconductor interfaces, the singlet fission materials tetracene and pentacene on H/Si(111), using all-electron density functional theory calculations with a hybrid exchange-correlation functional. For isolated tetracene on H/Si(111), a type I-like heterojunction (lowest-energy electron and hole states on Si) is found. For isolated pentacene, the molecular and semiconductor valence band edges are degenerate. For monolayer films, we show how to construct supercell geometries with up to 1192 atoms, which minimize the strain between the inorganic surface and an organic monolayer film. Based on these models, we predict the formation of type II heterojunctions (electron states on Si, hole-like states on the organic species) for both acenes, indicating that charge separation at the interface between the organic and inorganic components is favored. The paper discusses the steps needed to find appropriate low-energy interface geometries for weakly bonded organic molecules and films on inorganic substrates from first principles, a necessary prerequisite for any computational level alignment prediction.