Using Spacer Molecular Structure to Control Energetics, Stability, Charge-Carrier Transport, and Photovoltaic Performance in 2D Organic Metal Halide Perovskites

利用间隔分子结构控制二维有机金属卤化物钙钛矿的能量、稳定性、载流子传输和光伏性能

• 批准号: 2102257
• 负责人: Kenneth Graham
• 金额: $ 36.51万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2102257&HistoricalAwards=false
• 关键词: Using; Spacer; Molecular; Structure; Control

Nontechnical DescriptionOrganic metal halide perovskites (HPs) are attractive materials for high-performing inexpensive optoelectronic devices, such as photovoltaic cells and light emitting diodes, that can be fabricated using high-throughput approaches such as solution-based printing methods. Research scale photovoltaic cells based on HPs display record power conversion efficiencies that are on par with the most widely used photovoltaic material, silicon, but can be produced at a fraction of the cost of silicon photovoltaics. Although HPs have similar efficiencies to silicon, there are two major barriers to commercialization and wide scale deployment – inadequate stability and the presence of lead (Pb), a well-known toxic element. Reduced dimensionality HPs, which are a class of HPs where the three-dimensional (3D) perovskite structure is broken into 2D sheets by bulky organic cations, are promising materials for improving stability and enabling the replacement of Pb with tin (Sn), which is much less toxic. At present, photovoltaic devices based on reduced dimensionality HPs show significantly lower performance than their 3D counterparts, while Sn-based HPs also underperform their Pb-based counterparts. This project develops new reduced dimensionality HPs, with a stronger focus on the less toxic Sn-based materials, and determines key relationships between spacer structure and material properties, thus providing the understanding necessary to accelerate material development for more stable and less toxic photovoltaics and light emitting diodes. The research team promotes STEM education and interest at the middle and high school levels while emphasizing participation of traditionally underrepresented groups. This goal relies largely on an annual workshop for middle and high-school teachers from around Kentucky, where teachers conduct experiments in the organic electronics fabrication laboratory at the University of Kentucky and leave with the materials required to make dye sensitized solar cells with their middle and high school classes.Technical DescriptionThe performance of reduced dimensionality HPs is limited by their high exciton binding energies and poor electronic transport relative to their 3D counterparts, while the development of Sn-based HPs in general is limited by defect states resulting from Sn oxidation. Currently, it is hard to predict how molecular parameters of the spacer molecule, such as electrostatics, polarizability, or size, influence the optical and electronic properties of reduced dimensionality HPs. In part, these predictions are difficult because fundamental relationships between the molecular parameters of the spacer molecule and the ionization energy, electron affinity, and exciton binding energy of the reduced dimensionality HPs are largely unexplored. However, these parameters are critical to designing materials and device structures for photovoltaics and light emitting diodes. This research project systematically probes how the spacer molecule’s structure impacts these important material properties as well as stability, charge-carrier transport, and photovoltaic performance in both Pb- and Sn-based reduced dimensionality HPs. The project uses low-energy ultraviolet and inverse photoelectron spectroscopies to uncover critical relationships between spacer structure, crystal structure, ionization energy, and electron affinity in reduced dimensionality HPs. Next, the research focuses on how the spacer structure influences exciton binding energies in reduced dimensionality HPs and uses this knowledge to design materials with lower exciton binding energies. Third, spacer molecules are designed to inhibit Sn(II) oxidation and thereby provide a potential route for developing improved Sn-based HPs. Finally, selected reduced dimensionality HPs are incorporated into photovoltaic devices to determine how material properties such as exciton binding energies impact photovoltaic performance. Charge-carrier mobility measurements are conducted to establish more complete structure-property relationships that help to advance both material and device design.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.

非技术描述有机金属卤化物钙钛矿 (HP) 是用于高性能廉价光电器件（例如光伏电池和发光二极管）的有吸引力的材料，这些器件可以使用高通量方法（例如基于溶液的印刷方法）来制造。惠普显示创纪录的功率转换效率，与最广泛使用的光伏材料硅相当，但生产成本仅为硅的一小部分。尽管HP具有与硅相似的效率，但商业化和大规模部署存在两个主要障碍——稳定性不足和铅（Pb）的存在，铅是一种众所周知的降维有毒元素。三维 (3D) 钙钛矿结构被大体积有机阳离子分解成 2D 片的 HP 类材料，是有前途的材料，可提高稳定性并能够用锡 (Sn) 替代 Pb，而锡 (Sn) 的用量要少得多目前，基于降维 HP 的光伏器件的性能明显低于其 3D 供体，而锡基 HP 的性能也低于其基于铅的千克，该项目开发了新的降维 HP，并且更加注重毒性较小的产品。该研究团队致力于研究锡基材料，并确定间隔物结构和材料特性之间的关键关系，从而为加速材料开发提供必要的理解，以实现更稳定、毒性更低的光伏和发光二极管。这一目标在很大程度上依赖于肯塔基州各地初中和高中教师的年度研讨会，教师们在肯塔基大学的有机电子制造实验室进行实验。并在中学和高中课程中留下制作染料敏化太阳能电池所需的材料。技术描述降维 HP 的性能受到其高激子结合能和相对于其 3D 单元较差的电子传输的限制，而Sn基HP的发展通常受到Sn氧化产生的缺陷态的限制，目前，很难预测间隔分子的分子参数（例如静电、极化率或尺寸）如何影响还原的光学和电子特性。在某种程度上，这些预测是困难的，因为间隔分子的分子参数与降维 HP 的电离能、电子亲和力和激子结合能之间的基本关系在很大程度上尚未被探索。这些参数对于设计光伏和发光二极管的材料和器件结构至关重要，该研究项目系统地探讨了间隔分子的结构如何影响这些重要的材料特性以及稳定性、载流子传输和光伏性能。基于锡的降维 HPs 该项目使用低能紫外和反光电子能谱来揭示降维中间隔结构、晶体结构、电离能和电子亲和力之间的关键关系。接下来，研究重点是间隔结构如何影响降维 HP 中的激子结合能，并利用这些知识设计具有较低激子结合能的材料。第三，间隔分子被设计用于抑制 Sn(II) 氧化，从而提供最后，将选定的降维 HP 纳入光伏器件中，以确定激子结合能等材料特性如何影响光伏性能。建立更完整的结构-性能关系，有助于推进材料和设备设计。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Co-deposition of hole-selective contact and absorber for improving the processability of perovskite solar cells

共沉积空穴选择性接触和吸收剂以提高钙钛矿太阳能电池的加工性能

• DOI: 10.1038/s41560-023-01227-6
• 发表时间: 2023-05
• 期刊: Nature Energy
• 影响因子: 56.7
• 作者: Zheng, Xiaopeng;Li, Zhen;Zhang, Yi;Chen, Min;Liu, Tuo;Xiao, Chuanxiao;Gao, Danpeng;Patel, Jay B.;Kuciauskas, Darius;Magomedov, Artiom;et al
• 通讯作者: et al