Kowalik Patrycja, Bujak Piotr, Wróbel Zbigniew, Penkala Mateusz, Kotwica Kamil, Maroń Anna, Pron Adam
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
Faculty of Chemistry, University of Warsaw, Pasteura 1 Str., PL-02-093 Warsaw, Poland.
Inorg Chem. 2020 Oct 5;59(19):14594-14604. doi: 10.1021/acs.inorgchem.0c02468. Epub 2020 Sep 17.
A semiconducting molecule containing a thiol anchor group, namely 2-(5-mercaptothien-2-yl)-8-(thien-2-yl)-5-hexylthieno[3,4-]pyrrole-4,6-dione (abbreviated as D-A-D-SH), was designed, synthesized, and used as a ligand in nonstoichiometric quaternary nanocrystals of composition AgInZnS(S) to give an inorganic/organic hybrid. Detailed NMR studies indicate that D-A-D-SH ligands are present in two coordination spheres in the organic part of the hybrid: (i) inner in which the ligand molecules form direct bonds with the nanocrystal surface and (ii) outer in which the ligand molecules do not form direct bonds with the inorganic core. Exchange of the initial ligands (stearic acid and 1-aminooctadecane) for D-A-D-SH induces a distinct change of the photoluminescence. Efficient red luminescence of nanocrystals capped with initial ligands (λ = 720 nm, quantum yield = 67%) is totally quenched and green luminescence characteristic of the ligand appears (λ = 508 nm, quantum yield = 10%). This change of the photoluminescence mechanism can be clarified by a combination of electrochemical and spectroscopic investigations. It can be demonstrated by cyclic voltammetry that new states appear in the hybrid as a consequence of D-A-D-SH binding to the nanocrystals surface. These states are located below the nanocrystal LUMO and above its HOMO, respectively. They are concurrent to deeper donor and acceptor states governing the red luminescence. As a result, energy transfer from the nanocrystal HOMO and LUMO levels to the ligand states takes place, leading to effective quenching of the red luminescence and appearance of the green one.
设计、合成了一种含有硫醇锚定基团的半导体分子，即2-(5-巯基噻吩-2-基)-8-(噻吩-2-基)-5-己基噻吩并[3,4-]吡咯-4,6-二酮（简称为D-A-D-SH），并将其用作组成成分为AgInZnS(S)的非化学计量比四元纳米晶体中的配体，以形成无机/有机杂化物。详细的核磁共振研究表明，D-A-D-SH配体存在于杂化物有机部分的两个配位球中：（i）内层，其中配体分子与纳米晶体表面形成直接键；（ii）外层，其中配体分子不与无机核形成直接键。用D-A-D-SH取代初始配体（硬脂酸和1-氨基十八烷）会引起光致发光的明显变化。初始配体包覆的纳米晶体的高效红色发光（λ = 720 nm，量子产率 = 67%）完全猝灭，出现了配体特有的绿色发光（λ = 508 nm，量子产率 = 10%）。光致发光机制的这种变化可以通过电化学和光谱研究相结合来阐明。循环伏安法表明，由于D-A-D-SH与纳米晶体表面结合，杂化物中出现了新的状态。这些状态分别位于纳米晶体最低未占分子轨道（LUMO）之下和最高已占分子轨道（HOMO）之上。它们与控制红色发光的更深的供体和受体状态并存。结果，发生了从纳米晶体HOMO和LUMO能级到配体状态的能量转移，导致红色发光有效猝灭并出现绿色发光。
