Adjustable Electrochemiluminescence from Highly Passivated CdTe/CdS Nanocrystals by Simple Surface Decoration with Counterions

Abstract

Tunable optics and electronics of II-VI nanocrystals (NCs) is mainly achieved by using the traditional size-dependent strategy. Herein, we show that the triggering energy (potential), intensity, and even reductive-oxidation electrochemiluminescence (ECL) spectra of highly passivated CdTe/CdS NCs of the same size can be adjusted by simply decorating the NCs with counterions, which proves that surface chemistry can bring about varied electrostatic interactions between the surface vacancies and electrochemically injected carriers for adjustable electrochemical redox induced radiative charge transfer. Potential-resolved ECL demonstrates that increasing the surface sulfur vacancies and decreasing the surface cadmium vacancies can clearly enhance the ECL intensity and lower ECL triggering energy. All the traditional accumulated ECL spectra of CdTe/CdS NCs with various surface vacancies are close to the photoluminescence spectrum of monodisperse NCs without surface treatment, indicating the ECL spectra are mainly dominated by the CdTe core, whereas the slightly redshifted ECL spectrum of CdTe/CdS NCs with excessive cadmium vacancies indicates that the electrostatic repulsion between surface cadmium vacancies and electrons partially consumes the energy of the electrochemically injected electrons. Interestingly, spooling ECL spectra of CdTe/CdS NCs with varied surface vacancies are slightly blueshifted with negatively scanned potential, indicating electrons can be injected into conduction band of higher energy levels in a potential modulated way.

Novel Ru(bpy)2(cpaphen)2+/TPrA/TiO2 Ternary ECL System: An Efficient Platform for the Detection of Glutathione with Mn2+ as Substitute Target

“…4 In order to increase its response for analysis, the coreactant was introduced to form a binary system with luminophore for enhancing the ECL signal. 5,6 Generally, the excited state of the luminophore was generated through the reaction between the radical of luminophore and reactive intermediates of the coreactant produced by the electrochemical oxidation or reduction. 7,8 However, the reactive intermediates of the coreactant, as the key substance for the ECL intensity improvement, exhibited a relatively low generation rate on the electrode, which restricted the further improvement of the ECL signal.…”

Polarization-Resolved Electrochemiluminescence Sensor Based on the Surface Plasmon Coupling Effect of a Au Nanotriangle-Patterned Structure

“…In accordance with the variation trend of fluorescence intensity, the ECL intensity decreased constantly after increasing the volume of ethanol. This was related to the electrostatic interaction between the vacancies and carriers, 28 which sped up the electron transfer and obtained highly efficient electron−hole recombination. 29 Meanwhile, the SnS 2 QDs in Figure S3B displayed excellent ECL stability.…”

Progress in spectrum-based electrochemiluminescence quantitative analysis

“…双稳定剂包被技术同样适用于制备表面钝化的 CdZnSe [40] 、CdTe/CdS [38] 、CdTe/ZnSe [78] 以及Co 2+ 掺 杂CdTe (Co-CdTe)量子点 [56] , 所制备量子点的ECL光 谱与光致发光光谱基本一致. 在前驱体中引入Zn 2+ 能 够制备双稳定剂包被的三元CdZnSe量子点 [40] ; 由Zn 2+ 掺杂形成的内部缺陷导致CdZnSe量子点在长波区出 现缺陷辐射, CdZnSe量子点的ECL与光致发光均为双 波段辐射 [40] .…”

“…[37] . 该原型机既能基于CCD持续曝光成像 的摄谱方式准确检测超弱ECL的总光谱 [37] , 又能基于 CCD瞬时曝光成像的摄谱方式采集即时ECL光谱 [38,39] , 已在光谱型ECL定量分析研究领域获得应用 [40] . 总体 来说, 适用于定量分析的ECL光谱仪原型机所涉及的…”