CREST-Postdoctoral Research Fellowship: The Effects of Strong Confinement in the Ultrasmall Nanoparticle Regime on the Mechanism and Charge Transfer Rates in CdSe QDs

科学与技术卓越研究中心博士后研究奖学金（CREST- prf）项目支持具有重大潜力的CREST中心研究人员，并为他们提供培训和研究经验，以拓宽视野，促进跨学科互动，并使他们在科学界处于领导地位。该CREST- prf项目与纽约城市学院CREST低维结构界面设计和工程装配中心（CREST- ideals）的研究重点相一致。本研究的目的是了解超小型CdSe量子点（QDs）的光电特性。量子点是纳米级的，其光学和电子特性与较大的粒子不同。量子点有潜力挖掘太阳能的巨大潜力。利用x射线光谱学和透射电子显微镜技术对其合成的超小量子点进行了研究。这些技术将使研究人员能够更充分地了解超小型量子点转移电荷的能力，并制定理论模型来解释这种行为。这一分析将允许将超小量子点整合到太阳能电池设计中。超小量子点虽然具有单分散性，但具有宽发射特性。光致发光激发（PLE）将允许研究哪些激发波长可以引起特定波长的发射。初步的PLE数据表明，在带隙内存在可以直接吸收的状态。从量子点收集的PLE数据将与时间分辨光致发光数据（TRPL）进行比较。TRPL允许人们检测多指数衰减系统，表明这样的系统有多个生命周期。用x射线光电子能谱（XPS）和透射电子显微镜（TEM）对两种受体进行了研究。受体种类包括a)同时具有供电子和接受电子特性的分子（配体）和b)碳纳米管（CNTs）。分子将从研究不同链长的烷基硫醇和苯磺酸一水合物（BSAM）开始。将量子点嵌入碳纳米管中，不仅可以增强电荷转移，还可以实现量子点对齐，从而实现量子点之间的连接。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Centers of Research Excellence in Science and Technology-Postdoctoral Research Fellowship (CREST-PRF) track within the CREST program supports beginning CREST Center investigators with significant potential and provides them with training and research experiences that will broaden perspectives, facilitate interdisciplinary interactions and establish them in positions of leadership within the scientific community. This CREST-PRF project is aligned with the research focus of the CREST Center for Interface Design and Engineered Assembly of Low Dimensional Structures (CREST-IDEALS) at the City College of New York. The goal of this research is understanding the optoelectronic properties of ultrasmall CdSe quantum dots (QDs). Quantum Dots are on the nano scale which results in optical and electronic properties that are different from larger particles. QDs have the potential to tap into the enormous potential of Solar Energy. The proposed work intends to investigate ultrasmall quantum dots synthesized by the researcher with x-ray spectroscopy and transmission electron microscopy techniques. These techniques will allow the researcher to more fully understand the ability of ultrasmall quantum dots to transfer charge and formulate a theoretical model to explain the behavior. This analysis will allow the incorporation of ultrasmall QDs into solar cell designs. Ultrasmall quantum dots display broad emission despite their monodispersity. Photoluminescence excitation (PLE) will allow for the investigation of which excitation wavelengths can cause the emission of a specified wavelength. Preliminary PLE data indicates that there are states within the bandgap to which direct absorption is possible. PLE data gathered from Qds will be compared to time resolved photoluminescence data (TRPL). The TRPL allows one to detect multiexponential decay systems, indicating that such systems have multiple lifetimes. Two acceptor species will be investigated with x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The acceptor species include a) molecules (ligands) of both e- donating and e- accepting character and b) carbon nanotubes (CNTs). The molecules will begin with investigating alkylthiols of varying chain length and benzene sulfonic monohydrate (BSAM). Qds will be embedded within CNTs as a means of not only charge transfer enhancement but also QD alignment for connectivity between QDs as well.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.