SiO_2钝化提高CdSe/ZnS量子点的发光稳定性

Enhancement of Photo-stability of Colloidal CdSe/ZnS Quantum Dots Passivated in SiO_2

光诱导功能退化是胶体量子点在应用中面临的主要挑战之一,本文针对这一问题研究了使用磁控溅射沉积SiO_2薄膜形成钝化层来提高CdSe/ZnS量子点发光稳定性的方法。首先,通过三正辛基膦辅助连续离子层吸附反应方法合成了615 nm发光的红色CdSe/ZnS量子点。然后将量子点旋涂在SiO_2/Si基片上,再通过磁控溅射方法在量子点上沉积了厚度为20 nm的SiO_2薄膜作为钝化层。使用连续波激光光源分别在空气气氛和真空条件下照射样品,研究了经过不同照射时间后钝化和未钝化量子点的稳态光致发光光谱。结果表明,随着照射时间的延长,没有SiO_2钝化的量子点的PL强度显著降低、PL峰值发生蓝移、FWHM不断增大。对比研究发现,由于SiO_2薄膜能够阻挡空气中的水和氧,减缓了量子点表面的光诱导氧化现象,因此显著提高了CdSe/ZnS量子点的稳定性。

The photo-instability and degradation of colloidal quantum dots(QDs)are major challenges in their applications.We report photo-stability enhancement of colloidal CdSe/ZnS QDs passivated in SiO 2 thin film deposited by RF magnetron sputtering.First,the red(615 nm emission)CdSe/ZnS QDs were synthesized by tri-n-octylphosphine assisted successive ionic layer adsorption and reaction method.The QDs were then spin-coated to the SiO 2/Si substrate,and a SiO 2 film with a thickness of 20 nm was deposited on the QDs as a passivation layer by magnetron sputtering.The photoluminescence spectra of passivated and un-passivated QDs were investigated by using a continuous wave laser source,which was irradiated in air and vacuum respectively.The results show that the PL intensity of the QDs without SiO 2 passivation decreases significantly,and the PL peak shifts to blue and the FWHM increases continuously with the increasing of the irradiation time.Comparative analysis shows that SiO 2 film can prevent the oxidation of QD surface from water vapor and oxygen molecules and thus the stability of CdSe/ZnS QDs is significantly improved.