Engineering All-Inorganic Quantum Dot Heterojunction Photovoltaics Through Surface Chemical Manipulations

主要研究者：Kagan，Cherie提案编号：1236406机构：宾夕法尼亚大学职称：胶体半导体量子点（QD）有望成为低成本、大面积、高性能的太阳能光致发光材料（PV），因为它们可以从类似墨水的溶液中加工，并且它们具有尺寸、形状、和组成依赖的电子和光学性质，独特地允许从纳米级构建块设计和制造全无机材料。挑战在于利用固体薄膜中这些可溶液加工的QD的珍贵电子特性，其中需要容易的电荷传输和掺杂来设计用于高效太阳能PV的结，以及更广泛地用于半导体电子和光电器件。量子点固体薄膜的大面积比表面积、化学计量平衡以及量子点之间的耦合对量子点固体薄膜中载流子的类型和输运有很大影响。该项目将进行化学转化，以操纵固态薄膜中QD的表面化学和化学计量，同时原位探测其表面化学和电学性质，以设计高迁移率，n型和p型QD薄膜和高效pn异质结PV。 例如，湿化学合成方法产生宏观量的胶体半导体QD，其可以在尺寸、形状和组成上定制并且通过旋涂和浸涂像油墨一样沉积以形成大面积均匀QD薄膜。在这里，PI将使用最近开发的硫氰酸铵处理来交换薄膜中的QD，以形成强电子耦合和几乎裸露的QD，为随后的化学转化提供位点。 电化学，光学和电学测量将被用来表征的能级和载流子类型，陷阱，和流动性，因为我们修改量子点薄膜。高迁移率，长载流子寿命的量子点薄膜的电子结构，以确定大的结偏移量将被集成到太阳能电池和优化，以形成宽带，高吸收的量子点薄膜，为高效的太阳能光伏电池。拟议的研究活动将发展的表面，化学计量，和外来原子的作用的理解弱量子限制，较宽的带隙和更强的量子限制，更小的带隙量子点。表面的作用在设计高载流子迁移率的n型和p型材料中非常重要，这些材料不仅影响太阳能光电器件，而且影响广泛的可持续电子和光电器件的设计;低功率电子器件，能量收集热电器件和低功率发光二极管;从溶液可加工的QD材料开始。基本的理解和技术的发展将扩大纳米结构材料和化学转化过程的知识和教学和材料的设计，适用于不断增长的纳米结构材料的工具箱。该计划将为本科生和研究生提供跨学科的研究经验。它还将为学生和PI提供一个机会，通过演示，演示以及正式和校外课程，与K-12学生和教师，公众和科学界分享可持续和纳米级技术的科学和工程。

PI: Kagan, CherieProposal Number: 1236406Institution: University of PennsylvaniaTitle: Engineering All-Inorganic Quantum Dot Heterojunction Photovoltaics Through Surface Chemical ManipulationsColloidal semiconductor quantum (QDs) promise low-cost, large-area, high performance solar photovoltaics (PVs) as they may be processed from solution like inks and they have size, shape, and composition-dependent electronic and optical properties uniquely allowing the design and fabrication of all-inorganic materials from nanoscale building blocks. The challenge is to harness the prized electronic properties of these solution-processable QDs in solid thin films where facile charge transport and doping are required to engineer junctions for efficient solar PVs and more broadly for semiconductor electronic and optoelectronic devices. The large area surface (to volume), stoichiometric balance, and coupling between QDs greatly affect charge carrier type and transport in QD solid thin films. This project will carry out chemical transformations to manipulate the surface chemistry and stoichiometry of QDs in solid state thin films while probing in-situ their surface chemistry and electrical properties to design high mobility, n- and p-type QD thin films and high efficiency pn heterojunction PVs. For example, wet-chemical synthetic methods yield macroscopic quantities of colloidal semiconductor QDs that may be tailored in size, shape, and composition and deposited like inks by spin- casting and dip-coating to form large-area, uniform QD thin films. Here, the PI will exchange the QDs in thin films using the recently developed ammonium thiocyanate treatment to form strongly electronically coupled and nearly bare QDs, providing sites for subsequent chemical transformations. Electrochemical, optical and electrical measurements will be used to characterize the energy levels and carrier type, trapping, and mobility as we modify QD films. High mobility, long carrier lifetime QD films with electronic structures tailored to define large junction offsets will be integrated into solar cells and optimized to form broad band, high absorption QD films for efficient solar PVs.The proposed research activities will develop understanding of the role of surface, stoichiometry, and extrinsic atoms in weakly quantum confined, wider band gap and more strongly quantum confined, smaller band gap QDs. The role of the surface is important in designing high carrier mobility, n- and p-type materials that impact not only solar photovoltaics, but the design of a broad range of sustainable electronic and optoelectronic devices; low-power electronics, energy harvesting thermoelectrics, and low-power light-emitting diodes; pursued from solution-processable QD materials. The fundamental understanding and technological developments will expand knowledge and teaching of nanostructured materials and of processes for chemical transformations and design of materials, applicable to the growing toolbox of nanostructured materials. The program will provide an interdisciplinary research experience for undergraduate and graduate students. It will also provide an opportunity for the students and PI to share the science and engineering of sustainable and nanoscale technologies with K-12 students and teachers, the public, and the scientific community through demos, presentations, and formal and extramural coursework.