Type-II hot carrier solar cells: control and manipulation of non-equilibrium carriers using band engineering

II型热载流子太阳能电池：利用能带工程控制和操纵非平衡载流子

• 批准号: 1610062
• 负责人: Ian Sellers
• 金额: $ 38万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610062&HistoricalAwards=false
• 关键词: Type; II; hot; carrier; solar

Abstract: Control and manipulation of thermal losses in quantum-engineered structures: a practical route to high efficiency hot carrier solar cells.Non-technical: Improved solar cells are vital not only to the U.S. economy and energy independence; they are essential to the reduction in global warming and for economic growth throughout the developing world. Solar cells offer a free and abundant source of clean power, but currently operate at efficiency levels that limit their economic viability. The central issue is that solar cells convert considerably less of the sun's energy to useable power than fundamentally possible. One major loss mechanism is the rapid loss of energy through heat generation when high energy photons of light are absorbed. This program addresses mitigation of these hot carrier losses via a fundamental investigation of quantum-engineered solar cell architectures that have been shown to inhibit heat generation in proof-of-principle studies. Improved versions of the solar cell structures will facilitate the control and manipulation of hot carriers to increase the fraction of solar energy that is converted into electricity. The development and operation of such structures offer a real potential for practical hot-carrier solar cells, which have the potential to impact utility-scale power generation supporting existing utility infrastructure during peak operating periods, increasing global capacity, and reducing dependence on traditional fossil fuels. Through involvement in this program, graduate and undergraduate students develop expertise in a multidisciplinary range of technical skills, and gain a unique perspective of fundamental research while acquiring an appreciation of the subtleties of novel technology development. Technical: The project focuses on quantum-engineered structures based on Antimonide and Arsenide heterostructures. Despite several potentially important advantages, these semiconductors are relatively unexplored for next generation solar cells. The research builds on recent advances at the University of Oklahoma showing stable and robust hot carrier populations at elevated temperatures in Indium Arsenide (InAs)/Aluminium Arsenide Antimonide (AlAsSb) superlattices. The generation of "hot" high energy carriers has been observed to be more stable in quantum wells, in general, particularly at low temperatures where thermal losses are inhibited. These effects, however, are rapidly quenched at higher temperatures, conditions in which real solar cells must operate. InAs/AlAsSb superlattices are ideal for studying the physics of hot carriers in semiconductor structures. The large confinement potential in these structures facilities hot carrier generation directly in the quantum wells. The degenerate valence band improves the extraction of the positive charge carriers (holes), which serves to slow hot carrier relaxation through increased electron lifetimes in the conduction band of the superlattice. In solar cells designed to harness hot carriers, direct absorption will create hot carriers in quantum wells in the upper emitter region of the cell, which are then rapidly extracted via superlattice and resonant tunnelling architectures. Confinement can be used to tune the energy-gap to optimize the operating voltage, while effectively harnessing the hot carriers generated by the UV-visible photons of the solar spectrum. The semiconductor heterostructures will be grown by molecular beam epitaxy and their hot carrier properties will be characterized by optical spectroscopy and optoelectronic measurements. Solar cell devices will be fabricated from optimized structures with the goal of improved efficiency. Investigation of these structures and devices will enable a better understanding of hot carrier dynamics in practical systems, which are of great interest to the photovoltaics community and important for the cost-effective implementation of solar cells in the domestic energy market.

摘要：量子工程结构中热损失的控制和操纵：高效热载体太阳能电池的实用途径。没有技术：改善的太阳能电池不仅对美国的经济和能源独立性至关重要；它们对于减少全球变暖和整个发展中国家的经济增长至关重要。 太阳能电池提供了自由而丰富的清洁能源来源，但目前以限制其经济生存能力的效率水平运行。中心问题是，太阳能电池将太阳能量的转换为可用的功率要比根本上的可能性少得多。一种主要的损失机制是当吸收高能量光子时通过热量产生能量的迅速损失。该计划通过对量子工程太阳能电池结构进行的基本研究来解决这些热载体损失，这些太阳能电池结构已被证明在原理学证明研究中抑制了热量的产生。改进的太阳能电池结构的版本将有助于控制和操纵热载体，以增加转化为电能的太阳能的比例。此类结构的开发和运行为实用的热载波太阳能电池提供了真正的潜力，这些电池有可能影响公用事业规模的发电，从而在高峰运营期间支持现有的公用事业基础设施，增加了全球能力，并降低了对传统化石燃料的依赖。通过参与该计划，毕业生和本科生在多种技术技能方面发展了专业知识，并获得了基本研究的独特视角，同时获得了对新技术开发的微妙之处。技术：该项目重点介绍基于抗氧化剂和砷异质结构的量子工程结构。尽管有几个潜在的重要优势，但对于下一代太阳能电池，这些半导体却相对尚未探索。这项研究以俄克拉荷马大学的最新进展为基础，在砷化胺（INAS）/铝砷氧化铝抗氨基奈德（AlassB）超级晶格中的温度升高时显示了稳定稳定的热载体种群。通常，已经观察到“热”高能载体在量子井中更稳定，尤其是在抑制热损耗的低温下。但是，这些作用在较高的温度下迅速淬灭，实际太阳能电池必须运行。 INAS/AlassB超晶格是研究半导体结构中热载体物理学的理想选择。这些结构设施中的巨大限制潜力直接在量子井中的热载体生成。退化的价带改善了正电荷载体（孔）的提取，从而通过在超级晶体的传导带中增加电子寿命来减慢热载体松弛。在设计用于利用热载体的太阳能电池中，直接吸收将在电池上部发射极区域的量子井中创建热载体，然后通过超晶格和共振隧道架构迅速提取。可以使用限制来调整能量空隙以优化工作电压，同时有效利用太阳能光谱的UV可见光子产生的热载体。半导体异质结构将通过分子束外延生长，其热载体性能将以光谱和光电测量为特征。太阳能电池设备将从优化的结构中制造，以提高效率。对这些结构和设备的调查将使对实用系统中的热载体动力学有更好的了解，这对光伏社区引起了极大的兴趣，对于在国内能源市场中实施太阳能电池的成本效益很重要。