Ultrafast multiexciton kinetics in solar photovoltaics beyond the Shockley-Queisser limit

首席调查者：黄志伟编号：1438147太阳代表着地球上最丰富的潜在无污染能源。用于发电的太阳能电池需要吸收太阳能量并将其光子转化为电子的材料，这一过程被称为光伏。为了与化石燃料竞争，必须降低太阳能光伏系统的成本，这在一定程度上是通过提高太阳能转换效率和降低太阳能光伏材料的成本来实现的。最近，人们发现了新的光伏材料，利用纳米级的无机半导体化合物的量子物理行为来提高太阳能的转换效率。通过对光与这些材料的相互作用的基本了解，为下一代光伏设备发现新的廉价材料成为可能。该项目的目标是对纳米结构光伏材料中的量子物理过程有一个基本的了解，该材料将单光子从光转换为多个电子，从而超过单电子的Shockley Queisser极限。这项研究将利用先进的光谱技术，可以探测超快尺度上的多激子产生过程。该项目提供的教育活动集中于开发一系列关于太阳能、纳米科学和可持续能源的教学和实验模块，内容分别针对纽约市地区的小学生、低收入、准备上大学的高中生和哥伦比亚大学的本科生。这项研究将研究零维和表面修饰纳米结构中的超快多激子动力学和产生，以及一维纳米结构和组装中的超快多激子动力学和收集。这些信息将用于利用纳米结构光伏中的多激子能量和电子转移过程，以提高太阳能转换效率。超连续谱将被用来探测半导体纳米晶体、纳米棒和纳米结构中的多激子动力学和多激子效率，以阐明其基本机制。这些研究将扩展到研究透明的高迁移率石墨烯电极光伏中纳米结构的激子和电子转移，使用时间分辨和光谱分辨的研究，并通过单个纳米结构的闪烁统计来快速激子猝灭。该项目提供的教育和推广活动侧重于开发和提供一系列关于太阳能、纳米科学和可持续能源的教学和实验室模块，内容分别针对小学水平的学生、纽约市地区的低收入、准备上大学的高中生和哥伦比亚大学的本科生。

Principal Investigator: Chee Wei WongNumber: 1438147The sun represents the most abundant potential source of pollution-free energy on earth. Solar cells for producing electricity require materials that absorb the sun's energy and convert its photons to electrons, a process called photovoltaics. To be competitive with fossil fuels, the cost of solar photovoltaic (PV) systems must be reduced, which is realized in part by increasing the solar energy conversion efficiency and by reducing the cost of solar PV materials. Recently, new photovoltaic materials have been discovered that harness the quantum physics behavior of inorganic semiconductor compounds ordered at the nanoscale to increase the solar energy conversion efficiency. The discovery of new and inexpensive materials for this next generation of photovoltaic devices is enabled by fundamental understanding of the interaction of light with these materials. The goal of this project is to develop a fundamental understanding of quantum physics processes in nanostructured photovoltaic materials which convert a single photon from light into multiple electrons, and thus surpass the single electron Shockley Queisser limit. The research will make use of advanced spectroscopic techniques which can probe multiexciton generation processes at ultrafast scales. Educational activities offered by the project focus on the development of a series of teaching and laboratory modules on solar energy, nanoscience, and sustainable energy, with content targeted separately to grade-school level students, low income, college-bound high school students in the New York City area, and undergraduate students at Columbia University.Technical DescriptionThe overall goal of this project is to develop a fundamental understanding of multi-exciton generation in nanostructured photovoltaic materials. The proposed research will study ultrafast multiexciton kinetics and generation in zero-dimensional and surface-modified nanostructures, as well as ultrafast multiexciton kinetics and collection in one-dimensional nanostructures and assemblies. This information will be used to harness multiexciton energy and electron transfer processes in nanostructured photovoltaics for improved solar energy conversion efficiency. Super-continuum ultrafast spectroscopy will be used to probe multiexciton kinetics and multiexciton efficiencies in semiconducting nanocrystals, nanorods, and nanostructures to elucidate the fundamental mechanisms. These studies will be extended to examine exciton and electron transfer of nanostructures in transparent high-mobility graphene electrode photovoltaics, using time- and spectrally-resolved studies and fast exciton quenching through blinking statistics of single nanostructures. Educational and outreach activities offered by the project focus on the development and delivery of a series of teaching and laboratory modules on solar energy, nanoscience, and sustainable energy, with content targeted separately to grade-school level students, low income, college-bound high school students in the New York City area, and undergraduate students at Columbia University.