CAREER: Air Stable and Tunable Bandgap Pb-free Halide Perovskite Materials for Photovoltaic and Photocatalytic Applications

该CAREER项目旨在开发高效无铅钙钛矿太阳能电池，并确定这些新材料的稳定性。铅基有机-无机卤化物钙钛矿（OIHP）太阳能电池在不到十年的时间里表现出巨大的潜力，效率大幅提高。然而，由于Pb的存在和差的稳定性，这些材料可能对OIHP太阳能电池的广泛使用和商业化造成问题。研究界还没有提出一种高性能的替代铅基OIHP太阳能电池，主要是由于材料缺陷。该项目将开发空气稳定和低缺陷密度的Pt-Ni和Sn-Ge基钙钛矿太阳能电池。该项目的成功将导致开发具有稳定缓冲和接触材料的无铅钙钛矿太阳能电池模型系统。将开发寿命预测和平准化能源成本（LCOE）模型，以确定铅替代对电池成本、能源产量、效率、降解率、封装成本和回收的影响。除了这些科学进步，PI还将为代表性不足的少数民族研究生和本科生提供能源应用材料方面的培训。这个职业项目还将在内华达州的社区学院和UNLV培训下一代太阳能工作人员。将与学术界和工业界合作伙伴共同举办一系列专门的研讨会，以确定开发高效无铅钙钛矿材料的基本障碍。有机-无机卤化物钙钛矿（OIHP）作为低成本、溶液可印刷的半导体，具有上级光电性能，已取得重大进展。对于光伏应用，这些材料已经实现了25.2%的单结和29.1%的钙钛矿-Si串联器件的显着功率转换效率。尽管OIHP具有优异的性能，但Pb的毒性、热稳定性和离子迁移引起的稳定性是需要解决的基本材料问题。由于高缺陷密度和低吸收系数，Pb基OIHP的上级光电性能尚未在无铅组合物中再现。本研究的目标是开发具有可调带隙和高载流子寿命的全无机混合卤化物-硫属化合物无铅钙钛矿光吸收剂ABX 3和A2 BX 6（A = Cs; B = Ge/Sn，Pt/Ni; X = I，Cl，Br，O，S）。具有最佳能带偏移的无掺杂无机电子和空穴传输层将被开发用于高效率和稳定的平面太阳能电池。本论文的主要工作包括：（1）制备具有低间隙缺陷密度和高吸收系数的稳定的混合卤化物-硫族化合物无铅钙钛矿薄膜;（2）研究在结偏压、光照、热、氧、紫外线和湿度下的稳定性和退化机制;（3）改进电子和空穴传输层的表面和界面缺陷钝化;（4）高效率和稳定的无铅钙钛矿太阳能电池;（5）用于无铅钙钛矿太阳能电池的寿命预测和LCOE的加速应力测试方案和数值模型;以及（6）Pb与无铅钙钛矿太阳能电池的成本-稳定性-性能权衡分析。实现对如何控制无铅钙钛矿光吸收剂的电子、化学、电化学和动力学行为的基本理解，将为光伏应用及其他领域提供全新一代的宽带隙半导体。将形成关键的国际合作，以应对高效无铅钙钛矿太阳能电池的关键挑战。该项目由电气、通信和网络系统部门（ECCS）和激励竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This CAREER project aims to develop high efficiency Pb-free perovskite solar cells and determine the stability of these novel materials. Pb-based organic-inorganic halide perovskite (OIHP) solar cells have shown tremendous promise with big leap in efficiency in less than a decade. However, due to presence of Pb and poor stability, these materials may pose issues for widespread use and commercialization of OIHP solar cells. The research community has not yet come up with a high performance alternative to Pb-based OIHP solar cells, primarily due to material defects. This project will develop air-stable and low defect density Pt-Ni and Sn-Ge based perovskite solar cells. Success in this project will result in development of a model system for Pb-free perovskite solar cells with stable buffer and contact materials. Lifetime prediction and levelized cost of energy (LCOE) models will be developed to determine the effect of Pb replacement on cell cost, energy yield, efficiency, degradation rates, encapsulation costs and recycling. In addition to these scientific advancements, PI will train underrepresented minority graduate and undergraduate students on materials for energy applications. This CAREER project will also train the next generation workforce for solar energy jobs in Nevada at community colleges and UNLV. Dedicated workshop series to identify the fundamental roadblocks for development of high efficiency and Pb-free perovskite materials will be hosted in collaboration with academia and industry partners.Organic-inorganic halide perovskites (OIHPs) have shown significant progress as low-cost, solution printable semiconductors with superior optoelectronic properties. For photovoltaic applications, these materials have achieved remarkable power conversion efficiency of 25.2% single-junction and 29.1% perovskite-Si tandem devices. Despite the exceptional performance of OIHPs, toxicity of Pb, thermal stability, and stability due to ion migration are fundamental materials issues that need to be solved. The superior optoelectronic properties of Pb-based OIHPs have not yet been reproduced in Pb-free compositions due to high defect density and low absorption coefficient. The objectives of the proposed research are to develop all inorganic mixed halide-chalcogenide Pb-free perovskite photoabsorbers ABX3 and A2BX6 (A = Cs; B = Ge/Sn, Pt/Ni; X = I, Cl, Br, O, S) with tunable bandgap and high carrier lifetime. Dopant-free inorganic electron and hole transport layers with optimal band offsets will be developed for high efficiency and stable planar solar cells. Proposed work will address following: (1) solution processing of stable mixed halide-chalcogenide Pb-free perovskite thin films with low midgap defect density and high absorption coefficient; (2) stability and degradation mechanisms under junction bias, light illumination, heat, oxygen, UV and humidity; (3) surface and interface defect passivation with improved electron and hole transport layers; (4) high efficiency and stable Pb-free perovskite solar cells; (5) Accelerated stress testing protocols and numerical models for lifetime prediction and LCOE for Pb-free perovskite solar cells; and (6) cost-stability-performance trade-off analysis of Pb vs. Pb-free perovskite solar cells. Achieving a fundamental understanding of how to control the electronic, chemical, electrochemical, and dynamics behavior of Pb-free perovskite photoabsorbers will enable an entirely new generation of wide bandgap semiconductors for PV applications and beyond. Key international collaborations will be formed to address critical challenges for high efficiency Pb-free perovskite solar cells. This project is jointly funded by the division of Electrical, Communications and Cyber Systems (ECCS) and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.