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：高效热载流子太阳能电池的实用途径。非技术：改进的太阳能电池不仅对美国经济和能源独立至关重要，而且对减少全球变暖和发展中国家的经济增长至关重要。 太阳能电池提供了免费和丰富的清洁能源，但目前的效率水平限制了其经济可行性。核心问题是，太阳能电池将太阳能转化为可用电力的能力远远低于基本可能的水平。一种主要的损失机制是当吸收高能光子时通过热产生的能量的快速损失。该计划通过对量子工程太阳能电池架构的基本研究来解决这些热载流子损耗的缓解问题，这些架构已被证明可以抑制原理验证研究中的发热。太阳能电池结构的改进版本将有助于控制和操纵热载流子，以增加转换为电能的太阳能的比例。这种结构的开发和运行为实用的热载流子太阳能电池提供了真实的潜力，这有可能影响在高峰运行期间支持现有公用事业基础设施的公用事业规模发电，增加全球容量，并减少对传统化石燃料的依赖。通过参与该计划，研究生和本科生在多学科的技术技能范围内发展专业知识，并获得基础研究的独特视角，同时获得对新技术发展微妙之处的欣赏。技术：该项目侧重于基于锑化物和砷化物异质结构的量子工程结构。尽管有几个潜在的重要优势，但这些半导体在下一代太阳能电池中相对未被开发。这项研究建立在俄克拉荷马州大学的最新进展基础上，该研究表明，在高温下，砷化铟（InAs）/砷化锑铝（AlAsSb）超晶格中的热载流子数量稳定而强大。已经观察到“热的”高能载流子的产生在量子威尔斯阱中通常更稳定，特别是在热损失被抑制的低温下。然而，这些效应在更高的温度下会迅速熄灭，而在更高的温度下，真实的太阳能电池必须工作。InAs/AlAsSb超晶格是研究半导体结构中热载流子物理的理想材料。在这些结构中的大限制势便利于直接在量子威尔斯中产生热载流子。简并价带改善了正电荷载流子（空穴）的提取，这用于通过增加超晶格的导带中的电子寿命来减缓热载流子弛豫。在设计成利用热载流子的太阳能电池中，直接吸收将在电池的上发射极区域中的量子威尔斯中产生热载流子，然后通过超晶格和共振隧穿架构快速提取热载流子。限制可用于调整能隙以优化工作电压，同时有效地利用太阳光谱的UV-可见光子产生的热载流子。半导体异质结将通过分子束外延生长，其热载流子特性将通过光谱学和光电测量来表征。太阳能电池器件将从优化的结构制造，目标是提高效率。这些结构和设备的调查，将使更好地了解热载流子动力学在实际系统中，这是非常感兴趣的photopherics社区和重要的成本效益的太阳能电池在国内能源市场的实施。