Excellence in Research: Spontaneous Nucleation Strategy for High-Quality Perovskite Films

太阳能被认为是解决能源危机问题最有前途的可再生能源之一，因为它清洁，免费，没有碳排放。太阳能电池可以通过光伏效应将太阳光直接转化为电能，为电子设备供电。目前，最先进的太阳能转换技术，例如硅太阳能电池不能满足低成本和高能量转换效率的要求，以使广泛使用。或者，钙钛矿太阳能电池（PSC）代表了一系列有前途的光伏系统，具有低成本和高能量转换效率。到目前为止，自2009年以来，PSC已实现25.7%的认证功率转换效率。钙钛矿薄膜的制备主要采用抗溶剂辅助法。在高再现性、大规模生产和大尺寸装置方面，抗溶剂辅助方法不适合于实际应用。该卓越研究（EiR）项目解决了使用挥发性溶剂通过非抗溶剂方法制备高效钙钛矿太阳能电池的问题。所提出的研究方法在高质量钙钛矿薄膜的制造中表现出显着的潜力，因为薄膜的生长是由溶剂挥发通过自发和同时过饱和成核策略引起的。该项目将提供对通过挥发性溶剂和添加剂制备和调整的钙钛矿前体的关键理解，以通过非抗溶剂方法控制高质量的钙钛矿薄膜生长。本项目还将研究非反溶剂方法中溶剂-溶质化学与PSC器件性能之间的关系。EiR项目基于通过非抗溶剂方法和先进的表征技术进行的可调钙钛矿薄膜生长，将提供在挥发性溶剂存在下定制晶体生长中的溶质-溶剂化学的见解，并通过非抗溶剂方法开发钙钛矿薄膜生长原理。这些研究将为薄膜生长和电池性能之间的桥梁提供全面的研究，包括化学键合、配位、成核和生长以及电池性能。本项目将1）探索碘铅酸盐在前驱体制备过程中的演变和溶剂挥发过程中钙钛矿晶体成核过程，并研究碘铅酸盐、溶剂和添加剂在溶液中的关系。2)从薄膜覆盖率、厚度、缺陷、裂纹和针孔等方面研究薄膜生长，作为溶剂挥发、前体老化和碘铅酸盐配位络合物的函数。3)研究了湿膜到固态钙钛矿薄膜的相变及钙钛矿薄膜的光伏特性。4)优化定向钙钛矿晶体生长，以获得高质量、少缺陷、大晶粒、大面积和高再现性的薄膜。该项目将通过溶质-溶剂相互作用的非抗溶剂方法引发钙钛矿薄膜制造的革命。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。

NON-TECHNICAL SUMMARYSolar energy is believed to be one of the most promising renewable energies to solve the energy crisis problem because it is clean, free, and has no carbon emissions. Solar cells can convert sunlight directly to electricity to power electronic devices by the photovoltaic effect. Currently, state-of-the-art solar energy conversion technologies, for example, silicon solar cells cannot meet the requirements of low cost and high energy conversion efficiency to enable broad use. Alternatively, perovskite solar cells (PSCs) represent a family of promising photovoltaic systems for low-cost and high energy conversion efficiency. To date, PSCs have achieved a certified power conversion efficiency of 25.7% since 2009. The perovskite films are predominantly prepared by the antisolvent-assisted method. The antisolvent-assisted method is not suitable for practical applications in terms of high reproducibility, large-scale production, and large-size devices. This Excellence in Research (EiR) project addresses the use of volatile solvents to prepare high-efficiency perovskite solar cells by a non-antisolvent method. The proposed research method exhibits significant potential in the fabrication of high-quality perovskite films because the film growth is caused by solvent volatilization via a spontaneously and simultaneously supersaturated nucleation strategy. This project will provide a critical understanding of the perovskite precursor prepared and adjusted by volatile solvents and additives to control the high-quality perovskite film growth via a non-antisolvent method. This project will also study the relationship between solvent-solute chemistry and PSC device performance in the non-antisolvent method. TECHNICAL SUMMARYThis EiR project, based on adjustable perovskite film growth by non-antisolvent methods and advanced characterization techniques, will provide insights into tailoring the solute-solvent chemistry in crystal growth in the presence of volatile solvents and develop perovskite film growth principles by non-antisolvent methods. The proposed investigations will provide the bridge between film growth and cell performance comprehensively including chemistry bonding, coordination, nucleation and growth, and cell performance. This project will 1) Probe the iodoplumbates evolution during the precursor preparation and perovskite crystal nucleation process during the solvent volatilization and investigate the relationship between iodoplumbates, solvents, and additives in the solution. 2) Investigate film growth in terms of film coverage, thickness, defects, cracks, and pinholes as a function of solvent volatilization, precursor aging, and iodoplumbate coordination complexes. 3) Study the phase transition from wet films to solid perovskite films and the photovoltaic properties of the perovskite films. 4) Optimize the oriented perovskite crystal growth toward high quality, few defects, large grains, large area, and high reproducibility films. This project will lead to a revolution of perovskite film fabrication by non-antisolvent methods via solute-solvent interactions.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.