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

这个CAREER项目旨在开发高效的无铅钙钛矿太阳能电池，并确定这些新材料的稳定性。在不到十年的时间里，基于铅的有机-无机卤化物钙钛矿（OIHP）太阳能电池在效率上有了巨大的飞跃。然而，由于铅的存在和稳定性差，这些材料可能会给OIHP太阳能电池的广泛使用和商业化带来问题。由于材料的缺陷，研究界还没有提出一种高性能的替代品来替代基于铅的OIHP太阳能电池。该项目将开发空气稳定和低缺陷密度的Pt-Ni和Sn-Ge钙钛矿太阳能电池。该项目的成功将导致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的发展。将开发寿命预测和平准化能源成本（LCOE）模型，以确定铅置换对电池成本、能量产量、效率、降解率、封装成本和回收的影响。除了这些科学进步之外，PI还将培训未被充分代表的少数民族研究生和本科生，学习能源应用材料。这个CAREER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。将与学术界和行业合作伙伴合作举办专门的系列研讨会，以确定开发高效和无铅钙钛矿材料的基本障碍。有机-无机卤化物钙钛矿（OIHPs）作为具有优异光电性能的低成本、溶液可印刷半导体，已经取得了重大进展。在光伏应用方面，这些材料实现了25.2%单结和29.1%钙钛矿-硅串联器件的显著功率转换效率。尽管oihp具有优异的性能，但铅的毒性、热稳定性和离子迁移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，铅基oihp的优越光电性能尚未在无铅组合物中重现。提出的研究目标是开发具有可调带隙和高载流子寿命的所有无机混合卤化物-硫系无铅钙钛矿光吸收剂ABX3和A2BX6 （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输运层将用于高效稳定的平面太阳能电池。研究方向为：(1)低中隙缺陷密度、高吸收系数的稳定的卤化物-硫族化物混合无铅钙钛矿薄膜的溶液制备；(2)结偏置、光照、热、氧、紫外线和湿度下的稳定性和降解机制；(3)表面和界面缺陷钝化，改进电子和空穴输运层；(4)高效稳定的无铅钙钛矿太阳能电池；(5)无铅钙钛矿太阳能电池寿命预测和LCOE的加速应力测试方案和数值模型；(6)铅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使光伏应用及其他应用的全新一代宽带隙半导体成为可能。将建立重要的国际合作，以解决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）和促进竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，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.