Passivation by Ultimate Ligand-Surface Activation Rationalized by NMR

近年来，动态核极化(DNP)增强的固体核磁共振波谱已被证明是表征具有挑战性的固体材料及其界面的一种强有力的技术。通过DNP，未配对电子自旋的大极化转移到所需的原子核，可以显著提高核磁共振实验的灵敏度。对于被未成对电子源包围的无机纳米粒子(NPs)，即所谓的极化剂，极化转移主要发生在它们的表面。因此，除了提高灵敏度外，还实现了表面选择性，这可以用于研究纳米粒子的表面化学。用无机配体(ILs)而不是传统的有机配体覆盖NPs是为了提高由NPs组成的固体中的电荷载流子寿命，通常被称为胶体量子点固体(CQDS)。输运性质和方法通用性的大幅提高导致研究人员探索了许多类型的IL来改善电荷载流子的迁移率。然而，对IL-NPS表面化学的详细了解仍然是一项具有挑战性的任务，因此仍然缺乏。该项目旨在将配体封端的CQDS的表面化学和界面与其性能相关联。用先进的DNP增强固体核磁共振波谱对IL-NPS修饰的NPs进行表面表征。光致发光和电导测量将显示组装的CQDS中电荷载流子寿命的影响。因此，这项研究将在原子水平上对IL选择和表面化学如何影响电荷输运产生突破性的理解，并将导致在CQDS中实现单晶级迁移率值的通用方法。

Dynamic nuclear polarization (DNP)-enhanced solid-state NMR spectroscopy has proven in recent years to be a powerful technique for the characterization of challenging solid materials and their interfaces. Substantially increased sensitivity of NMR experiments becomes possible through DNP, where the large polarization of unpaired electron spins is transferred to the desired nuclei. For inorganic nanoparticles (NPs) surrounded with sources of unpaired electrons, known as polarizing agents, polarization transfers are mainly to their surfaces. Therefore, surface selectivity, in addition to increased sensitivity, is achieved and this can be used to study the surface chemistry of NPs. The capping of NPs with inorganic ligands (ILs), rather than conventional organic ligands, has been proposed to improve charge carrier lifetime in solids composed of assemblies of NPs, usually termed colloidal quantum dot solids (CQDSs). Substantial increases in transport properties and method versatility have led researchers to explore many types of IL to improve the mobility of charge carriers. However, gaining a detailed understanding of the surface chemistry of IL-capped NPs remains a challenging task and is thus still lacking. This project aims to correlate the surface chemistry and interfaces of ligand-capped CQDSs with their performance. Surface characterization of IL-capped NPs will be carried out by advanced DNP-enhanced solid-state NMR spectroscopy. Photoluminescence and conductivity measurements will indicate the effect on charge carrier lifetimes in assembled CQDSs. Therefore, the proposed research will result in a breakthrough atomic-level understanding of how IL choice and surface chemistry influences charge transport and will lead to a generalized method for achieving single-crystal-grade mobility values in CQDSs.