EAGER: Transparent electrode device architecture for high efficiency tandem colloidal quantum dot photovoltaics

EAGER：用于高效串联胶体量子点光伏的透明电极器件架构

• 批准号: 1744671
• 负责人: Alexi Arango
• 金额: $ 8万
• 依托单位: Mount Holyoke College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744671&HistoricalAwards=false
• 关键词: EAGER; Transparent; electrode; device; architecture

AbstractNontechnical The emergence of lightweight, flexible, efficient, and affordable solar cell modules could revolutionize energy generation from the sun. Among the contending technologies, photovoltaics employing lead sulfide nanocrystalline films have been increasing in efficiency at one of the most rapid paces ever seen. However, two aspects limit the efficiency of these cells: how far electrons can move through the lead sulfide film and how many material defects exist in the nanocrystals. Tandem solar cells (multiple solar cells grown on top of one another) can circumvent these limitations because multiple thin cells can be stacked to achieve strong absorption across the whole cell. Surprisingly, previous attempts at fabricating two-layer tandem photovoltaics using lead sulfide nanocrystals have not achieved the dramatic gains in efficiency that would be expected. This project presents modeling data showing that at least five layers of cells must be stacked before significant enhancements in efficiency will be observed. A proof-of-principal device will be fabricated consisting of two solar cells connected with a transparent conducting metal oxide layer. The research will take place at Mount Holyoke College, a women's undergraduate college with a remarkable history of educating women in the sciences.TechnicalThe PI will fabricate a lead sulfide colloidal quantum dot photovoltaic in a tandem structure in order to enhance absorption in the critical long-wavelength region of the solar spectrum. Dramatic gains in the power conversion efficiency of colloidal quantum dot photovoltaics have been achieved over the past decade, but many of the best devices still suffer from low absorption in the infrared, a consequence of weak oscillator strength at the first excitonic transition peak, often resulting in more than a 50% reduction in absorption alone. The mismatch between the carrier diffusion length (ranging around 100 nm) and the thickness needed to absorb an appreciable amount of the solar spectrum (ranging around 500 nm) accounts for the shortfall in absorption. Preliminary modeling demonstrates that a five-junction tandem structure can achieve full absorption while allowing the maximum thickness of the lead sulfide layer in each sub cell to stay within 100 nm, achieving a straightforward, attainable pathway to realistic efficiencies approaching 19% and theoretical efficiencies approaching 28%. Tandem structures are an effective method of increasing absorption already employed in small molecule organic PV and elsewhere, but never before have had researchers assembled the tools needed to effectively construct five or more tandem junctions. The PI will fabricate a proof-of-principle tandem structure by employing a custom low-damage sputtering technique for the deposition of metal oxide transport layers and transparent conductors at the recombination zone, an integrated fiber-optic spectrophotometer for accurate absorption measurements coupled with careful optical modeling, an interconnected glovebox system for seamless device fabrication, and a revolutionary Thermo-reflectance imaging technique to map current flow and electric field non-uniformities.

【摘要】【非技术】轻量、灵活、高效且价格合理的太阳能电池模块的出现将彻底改变太阳能发电。在竞争技术中，采用硫化铅纳米晶体薄膜的光伏发电效率以前所未有的最快速度提高。然而，有两个方面限制了这些电池的效率：电子能在硫化铅薄膜中移动多远，以及纳米晶体中存在多少材料缺陷。串联太阳能电池（多个太阳能电池在另一个上面生长）可以绕过这些限制，因为多个薄电池可以堆叠在一起，以实现整个电池的强吸收。令人惊讶的是，之前使用硫化铅纳米晶体制造两层串联光伏的尝试并没有达到预期的效率的显著提高。该项目提供的建模数据显示，在观察到效率的显着提高之前，必须至少堆叠五层电池。将制作由两个太阳能电池与透明导电金属氧化物层连接组成的主要证明装置。这项研究将在芒特霍利奥克学院进行，这是一所女子本科学院，在教育女性科学方面有着非凡的历史。技术方面，PI将在串联结构中制造硫化铅胶体量子点光伏，以增强太阳光谱临界长波长区域的吸收。在过去的十年中，胶体量子点光伏电池的功率转换效率已经取得了巨大的进步，但是许多最好的设备仍然存在红外吸收低的问题，这是第一个激子跃迁峰弱振荡器强度的结果，通常导致吸收降低50%以上。载流子扩散长度（约100纳米）与吸收相当数量的太阳光谱所需的厚度（约500纳米）之间的不匹配是吸收不足的原因。初步建模表明，五结串联结构可以实现完全吸收，同时允许每个亚电池中硫化铅层的最大厚度保持在100 nm以内，从而实现直接可行的实际效率接近19%，理论效率接近28%。串联结构是一种有效的增加吸收的方法，已经应用于小分子有机PV和其他地方，但以前从未有研究人员组装有效构建五个或更多串联结所需的工具。PI将通过采用定制的低损伤溅射技术在复合区沉积金属氧化物传输层和透明导体来制造原理验证级串联结构，集成光纤分光光度计用于精确的吸收测量，并结合仔细的光学建模，互连手套箱系统用于无缝器件制造。以及革命性的热反射成像技术，用于绘制电流和电场的不均匀性。