The separation of photoexcited charge carriers at the quantum dot (QD)-dye interface is determined by the direction of the charge transfer and electronic coupling. We carried out DFT-based studies to analyze the variation of energy level alignment and the associated QD-dye electronic couplings with respect to the surface orientation of Ru505 dye adsorbed on a CdSe QD. Our calculations show that the structures with two carboxylate anchors have the most stable adsorption on the QD surface. These structures have comparable electronic couplings for electron transfer and back electron transfer, and also possess large electronic couplings for hole extraction from the QD, reducing the chance of photoexcited electrons returning to the QD ground state. Using a cyano group to couple a dye to a QD surface stabilizes the dye’s occupied orbitals, making hole extraction thermodynamically unfavorable. In addition, these structures show no improvement in their electronic couplings when the cyano group is introduced as anchors. Overall, our computational work advances our understanding of the surface chemistry of a CdSe QD functionalized by Ru505 dye, which may help design QD-based materials for photovoltaic and photocatalytic applications by manipulating the morphologies of QD-dye composites.

量子点 (QD)-染料界面处光激发电荷载流子的分离由电荷转移和电子耦合方向决定。我们进行了基于 DFT 的研究，以分析与吸附在 CdSe QD 上的 Ru505 染料的表面取向有关的能级排列和相关 QD 染料电子耦合的变化。我们的计算表明，具有两个羧酸盐锚的结构在 QD 表面上具有最稳定的吸附。这些结构对于电子转移和背电子转移具有相当的电子耦合，并且还具有用于从 QD 中提取空穴的大电子耦合，从而减少了光激发电子返回 QD 基态的机会。使用氰基将染料偶联到 QD 表面可以稳定染料的占据轨道，使空穴提取在热力学上不利。此外，当引入氰基作为锚点时，这些结构的电子耦合没有改善。总的来说，我们的计算工作增进了我们对 Ru505 染料功能化的 CdSe QD 表面化学的理解，这可能有助于通过操纵 QD 染料复合材料的形态来设计用于光伏和光催化应用的基于 QD 的材料。