EAGER: Finite-Absorption-Bandwidth Materials for Cost-Effective Multijunction Photovoltaics

摘要：非技术性：吸收可见光的商用太阳能电池正在达到其理论和实际效率极限。改善它们性能的理想策略是一种新材料，这种材料可以简单地“粘在”目前高性能的商业电池的顶部，使其能够收集太阳发出的不可见的红外辐射。该项目旨在通过使用具有依赖于纳米和微米结构的光学性质的半导体颗粒来构建一种新型的柔性材料，这种材料只吸收红外线，而传输可见光。具体地说，目标是在强吸收胶体量子点薄膜中制造光子晶体(某些频率范围的光不能传播的结构)，用于颜色调谐和透明的太阳能电池。该项目有可能通过开发轻质、廉价和灵活的太阳能收集材料，满足开发更高效的可再生能源技术的广泛社会目标，作为污染和不可持续的化石燃料的替代品。此外，这些材料可能是透明和建筑一体化太阳能电池的理想平台。该项目旨在解决不同长度尺度在纳米结构材料中的作用以及它们之间的相互作用如何决定光学和电子材料性能的基本问题。研究活动将与旨在向小学生、本科生和研究生介绍纳米技术和可持续工程领域的全面教育和推广计划相结合。技术：本研究的目标是构建具有有限吸收带宽的新型无机纳米材料，用于提高透明和多结太阳能电池的效率。该项目将采用一种创新的方法，基于强吸收胶体量子点薄膜材料中光子带隙的新实现，制造具有光谱定制吸收和透射谱的柔性纳米颗粒薄膜。将采用的方法包括计算模拟、化学合成、溶液处理器件制造以及电气和光学器件表征。如果研究成功，这项研究工作将带来一种新的方法，通过引入一种只在红外中吸收的新型有源光电材料来提高当前太阳能电池技术的效率。这些柔性光伏材料可以以经济高效的方式提高当前商业太阳能电池技术的效率：顶部的红外电池将可见光传输到底部标准的可见光电池，在多结结构中实现电流匹配，而无需重新设计现有的高性能太阳能电池技术。该项目还旨在回答一些悬而未决的问题，包括纳米物理现象之间的相互作用，如何在多个长度尺度上实现自组装和光学工程，以及人工光子带结构如何在强吸收介质中保持。该项目开发的新材料具有用于许多新技术的潜力，包括多结太阳能电池、透明光伏和其他光电子和光电子器件。

Abstract:Nontechnical: Commercial solar cells that absorb visible light are reaching their theoretical and practical efficiency limits. An ideal strategy for improving their performance would be a new material that could simply be "stuck on top" of a current high-performing commercial cell, allowing it to harvest the invisible infrared radiation emitted by the sun. This project seeks to build a new class of flexible materials that only absorb in the infrared while transmitting visible light by using semiconductor particles with optical properties that depend on their nano- and micro-scale structures. Specifically, the goal is to make photonic crystals (structures in which certain frequency ranges of light cannot propagate) in strongly absorbing colloidal quantum dot films, to be used in color-tuned and transparent solar cells. The project has the potential to address broad societal goals in the development of more efficient renewable energy technologies, as alternatives to polluting and unsustainable fossil fuels, by developing lightweight, inexpensive, and flexible solar energy harvesting materials. Additionally, these materials could be ideal platforms for transparent and building-integrated solar cells. The project seeks to address fundamental questions on the role of different length scales in nanostructured materials, and how the interplay between them determines optical and electronic materials properties. Research activities will be integrated with a comprehensive education and outreach plan designed to introduce elementary school students, undergraduates, and graduate students to the fields of nanotechnology and sustainable engineering. Technical: The objective of this study is to build new inorganic nanomaterials with finite absorption bandwidths that will be used to improve the efficiency of transparent and multi-junction solar cells. The project will take an innovative approach for making flexible nanoparticle films with spectrally-tailored absorption and transmission spectra based on novel realizations of photonic bandgaps in strongly absorbing colloidal-quantum-dot-based thin-film materials. Methods to be employed include computational simulations, chemical syntheses, solution-processed device fabrication, and electrical and optical device characterization. If successful, the research work will result in a new method for improving the efficiency of current solar cell technology by introducing a new class of active optoelectronic materials that absorb only in the infrared. These flexible photovoltaic materials could increase the efficiency of current commercial solar cell technology in a cost-effective way: the top infrared cells will transmit visible light to the bottom standard visible cells, achieving current-matching in a multi-junction structure without re-engineering current high-performing solar cell technology. This project also aims to answer open questions involving the interactions between nano-physical phenomena, how to achieve self-assembly and optical engineering on multiple length scales, and how artificial photonic band structures can be maintained in strongly absorbing media. The novel materials developed in this project have the potential to be used in a number of new technologies, including multi-junction solar cells, transparent photovoltaics, and other photonic and optoelectronic devices.