Excitons and Singlet Fission at the Crystalline Tetracene–Silicon Interface,Chemistry of Materials

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Excitons and Singlet Fission at the Crystalline Tetracene–Silicon Interface
Chemistry of Materials ( IF 7.2 ) Pub Date : 2024-02-20 , DOI: 10.1021/acs.chemmater.3c02731
Mykhailo V. Klymenko ₁ , Liang Z. Tan ₂ , Salvy. P. Russo ₁ , Jared H. Cole ₁

Affiliation

Excitons in organic crystalline semiconductors play a crucial role in the operation of optoelectronic devices, such as organic solar cells, light-emitting diodes, and photodetectors. The excitonic properties of materials are dramatically affected by the presence of surfaces and interfaces. Using the GW method and Bethe–Salpeter equation, we investigate the influence of a neutral hydrogen-passivated 1 × 2 reconstructed (100) silicon substrate on excitons within the crystalline tetracene layer deposited on the top of it. Our findings reveal that singlet excitons in the contact tetracene layer are situated within the continuum of unbound Wannier-Mott excitonic states in silicon, with noteworthy hybridization between these states. Consequently, in the contact tetracene layer, all singlet excitons exhibit a pronounced interlayer charge transfer character, while the triplet exciton remains confined to the tetracene layer. This makes the singlet fission effect highly improbable for the contact tetracene layer. Additionally, the presence of the silicon substrate results in a modification of the singlet–triplet gap by 144 meV. This change is solely attributed to hybridization with excitons in silicon, which influences the exchange energy. Our results show that the dynamic dielectric screening caused by the substrate does not impact the singlet–triplet gap but alters the exciton binding energies.

中文翻译：

晶体四苯-硅界面处的激子和单线态裂变

有机晶体半导体中的激子在有机太阳能电池、发光二极管和光电探测器等光电器件的运行中发挥着至关重要的作用。材料的激子性质受到表面和界面的存在的显着影响。使用 GW 方法和 Bethe-Salpeter 方程，我们研究了中性氢钝化的 1 × 2 重构 (100) 硅基板对其顶部沉积的结晶并四苯层内激子的影响。我们的研究结果表明，接触并四苯层中的单线态激子位于硅中未束缚的万尼尔-莫特激子态的连续体内，这些态之间存在值得注意的杂化。因此，在接触并四苯层中，所有单线态激子都表现出显着的层间电荷转移特性，而三线态激子仍然局限于并四苯层。这使得单重态裂变效应对于接触并四苯层来说极不可能发生。此外，硅衬底的存在导致单重态-三重态能隙改变 144 meV。这种变化完全归因于与硅中激子的杂化，这影响了交换能量。我们的结果表明，由基底引起的动态介电屏蔽不会影响单线态-三线态间隙，但会改变激子结合能。

更新日期：2024-02-20

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