Carrier Dynamics in Quantum Dot Solar Cells and Infrared Detectors

量子点太阳能电池和红外探测器中的载流子动力学

• 批准号: 1509712
• 负责人: Mario Dagenais
• 金额: $ 39.44万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509712&HistoricalAwards=false
• 关键词: Carrier; Dynamics; Quantum; Dot; Solar

Abstract:Abstract Title: "Understanding the enhancement mechanisms of optical energy conversion efficiency in solar cells based on confinement by quantum dots"Nontechnical:Photovoltaic is a technology that permits the conversion of abundant radiative energy from the sun to electrical energy which can ultimately be widely distributed using a smart electrical grid infrastructure. This can be done with a minimum negative impact on the environment. In spite of being a well-established clean source of energy, there is a need for improving the present conversion efficiency of Si solar cells. New materials and new approaches to achieve this goal have emerged. One appealing approach is based on using different materials with different bandgap to enhance the conversion efficiency of present solar cells. Another approach is based on using confined nanostructures, called quantum dots, to convert solar energy with high efficiency. This latter approach has the advantage of being simpler and does not require complex growth processes. This might be a very inexpensive approach to making solar cells. On the other hand, this approach has not yet demonstrated its potential. Different experimental studies are proposed with the goal of understanding the potential and limitations of this approach. The proposed approach involves an effort toward a better understanding of light absorption in these structures in order to design very efficient solar cells based on quantum dots. If successful, this project will have a major impact on clean and efficient energy conversion in this country.Technical:Photovoltaic devices based on p-n junction are the most mature technology for solar-energy harvesting. This proposal seeks to develop new highly efficient GaAs quantum dot solar cells based on the intermediate band concept. These cells have the potential of being as efficient as 3-junction solar cells but at a much lower level of complexity. The concept of intermediate band solar cells has been with us for more than 15 years. Unfortunately, these solar cells have so far demonstrated a limited conversion efficiency of 18 % or less. This is in large part related to the fact that researchers have not been able to demonstrate an intermediate band solar cell with a well-defined intermediate band Fermi energy, detached from the conduction band Fermi energy. Some key measurements on intermediate band solar cells that have not been attempted before are proposed in order to shed light on this topic. In particular, two-photon measurements using two optical sources of different wavelengths are proposed to understand if a 2-photon absorption can be measured and if the process is based on sequential photons absorption or due to simultaneous two-photon absorption. This will answer the question if intermediate band solar cells can be realized with well-defined intermediate band Fermi energy, detached from the conduction band Fermi energy. If substantially higher efficiencies cannot be reached using the concept of intermediate band solar cells, implying that the concept is basically flawed, this needs to be investigated and a final answer has to be provided with a clear explanation. Additionally, since the physics of these solar cells is similar to the physics describing photon absorption in IR-detectors, this new understanding will also lead to a better understanding of the operation of quantum dot infrared photodetectors (QDIPs). Two quantum dot solar cells will be studied with different bandgaps to optimize the predicted conversion efficiency of intermediate band solar cells.

摘要：摘要标题：“了解基于量子点约束的太阳能电池光能转换效率的增强机制”非技术：光伏是一种将太阳丰富的辐射能转换为电能的技术，最终可以得到广泛应用使用智能电网基础设施进行分布式。这样做可以将对环境的负面影响降到最低。尽管硅太阳能电池是一种成熟的清洁能源，但仍需要提高其现有的转换效率。实现这一目标的新材料和新方法已经出现。一种有吸引力的方法是基于使用具有不同带隙的不同材料来提高现有太阳能电池的转换效率。另一种方法是基于使用被称为量子点的受限纳米结构来高效转换太阳能。后一种方法的优点是更简单并且不需要复杂的生长过程。这可能是一种非常便宜的太阳能电池制造方法。另一方面，这种方法尚未展示其潜力。提出了不同的实验研究，目的是了解这种方法的潜力和局限性。所提出的方法涉及更好地理解这些结构中的光吸收，以便设计基于量子点的非常高效的太阳能电池。如果成功，该项目将对我国清洁高效的能源转换产生重大影响。 技术：基于p-n结的光伏器件是最成熟的太阳能收集技术。该提案旨在开发基于中能带概念的新型高效砷化镓量子点太阳能电池。这些电池具有与三结太阳能电池一样高效的潜力，但复杂性却低得多。中波段太阳能电池的概念已经存在超过 15 年了。不幸的是，迄今为止这些太阳能电池的转换效率有限，仅为 18% 或更低。这在很大程度上与以下事实有关：研究人员未能证明具有明确的中带费米能量（与导带费米能量分离）的中带太阳能电池。为了阐明这一主题，提出了一些以前从未尝试过的中波段太阳能电池的关键测量。特别是，建议使用两个不同波长的光源进行双光子测量，以了解是否可以测量 2 光子吸收，以及该过程是否基于顺序光子吸收或由于同时双光子吸收。这将回答是否可以利用与导带费米能量分离的明确的中带费米能量来实现中带太阳能电池的问题。如果使用中波段太阳能电池的概念无法达到显着更高的效率，则意味着该概念基本上是有缺陷的，需要对此进行调查，并且必须提供最终答案和明确的解释。此外，由于这些太阳能电池的物理原理与描述红外探测器中光子吸收的物理原理相似，这种新的理解也将有助于更好地理解量子点红外光电探测器 (QDIP) 的工作原理。将研究具有不同带隙的两种量子点太阳能电池，以优化中带太阳能电池的预测转换效率。