Charge Transport and Carrier-Phonon Interactions in Soft Lattice Metal Halide Perovskites

软晶格金属卤化物钙钛矿中的电荷传输和载流子-声子相互作用

• 批准号: 2324943
• 负责人: Xiangfeng Duan
• 金额: $ 52万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2026-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2324943&HistoricalAwards=false
• 关键词: Charge; Transport; Carrier; Phonon; Interactions

Non-technical DescriptionMetal halide perovskites are a unique class of “soft” semiconductors that have attracted enormous interest. They can be solution processed at relatively low temperatures and have shown promise for optoelectronic devices such as solar cells, light emitting diodes and radiation detectors. However, understanding charge transport in these materials remains elusive. Studies of charge transport are complicated by ion movement and the difficulty in forming high-quality electrical contacts. Furthermore, perovskites can degrade during processing or when depositing metal contacts on top of them. This results in excessive contact resistance and limits device performance. By physically laminating electrodes onto perovskite films, the team will avoid such degradation and be able to perform reliable electrical studies. They will combine studies of photocurrent and capacitance on temperature and light intensity with direct structural analysis. They will also vary contacts and use doping to further tailor the carrier density and explore unique phenomena in these materials. This systematic study will unravel the intriguing properties of perovskites and develop critical insights needed to design more efficient devices. The relevant research activities also offer valuable educational opportunities to students for training next generation of workforce in relevant technologies.Technical DescriptionThis project exploits a unique van der Waals integration strategy to create atomically clean contacts with greatly reduced contact resistance for a systematic electrical transport study of metal halide perovskites (MHPs). By physically laminating the prefabricated atomically flat thin film metal electrodes onto the perovskite thin films without directly exposing the perovskites to any lithography or deposition steps, this approach can effectively avoid the associated material degradations to achieve greatly reduced contact resistance for reliable electrical transport studies. The project will probe charge transport and photocarrier induced local lattice distortion, the associated phase transition, and their impact on the carrier dynamics and fundamental transport properties: including temperature- and illumination-dependent photo-conductance and photo-capacitance studies to probe carrier-phonon interactions, and their impact on the carrier recombination and transport properties; direct structural analysis to investigate the atomic structural change associated with the carrier generation under different illumination or temperature; developing different contacts or selective doping strategies to probe both electron and hole transport characteristics; using the optimized device fabrication and measurement protocols to probe the carrier-phonon interactions and ferroelectricity in low-dimensional MHPs and other related materials; and further tailoring the carrier density through a combination of chemical doping, electrical static doping and photodoping to probe carrier-phonon or carrier-carrier interactions and explore possible emergent phenomena. These research activities help develop a critical understanding of the fundamental photophysical, electrical transport properties, and the intriguing carrier-phonon interactions in this unique class of materials, which will not aim engineering improved photovoltaics or light-emitting diodes, but also help unlock new technological potentials from MHPs.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.

非技术描述金属卤化物钙质是一类独特的“软”半导体，引起了极大的兴趣。它们可以在相对较低的温度下进行处理，并显示出对光电设备（例如太阳能电池，发射二极管和辐射探测器）的希望。但是，了解这些材料中的电荷运输仍然是弹性的。电荷运输的研究因离子运动而变得复杂，并且很难形成高质量的电触点。此外，在加工过程中或在其顶部沉积金属触点时，钙钛矿可能会降解。这会导致过量的接触电阻和限制设备性能。通过将电子物理层压到钙钛矿膜上，该团队将避免这种降解并能够进行可靠的电力研究。他们将通过直接结构分析结合对温度和光强度的电容和电容的研究。它们还将改变接触，并使用掺杂来进一步量身定制载体密度并探索这些材料中的独特现象。这项系统的研究将揭示钙钛矿的有趣特性，并开发设计更有效的设备所需的关键见解。相关的研究活动还为学生提供了宝贵的教育机会，以培训相关技术的下一代劳动力。技术说明这一项目利用了独特的范德华集成策略，以创建原子清洁的接触，并大大降低了接触电阻，以实现金属卤化物钙钛矿（MHP）的系统电气传输研究。通过将预制的原子薄膜金属电子物理层压到钙钛矿薄膜上，而无需直接将perovskite暴露于任何光刻或沉积步骤中，此方法可以有效地避免相关的材料降解，从而大大降低了可靠的电气运输研究的接触电阻。该项目将探测运输和光载体引起的局部晶格失真，相关的相变及其对载体动力学和基本传输特性的影响：包括温度和照明依赖性的光电传导性以及对探针载体相互作用的相互作用及其对携带者相互作用的影响及其对载体重新组合和运输特性的影响；直接的结构分析研究与载体在不同照明或温度下产生相关的原子结构变化；开发不同的接触或选择性掺杂策略，以探测电子和孔传输特性；使用优化的装置制造和测量协议来探测低维MHP和其他相关材料中的载体 - 载体相互作用和铁电性；并通过化学掺杂，电静电掺杂和光载型的结合来进一步调整载体密度，以探测载体 - 载波或载体 - 载体相互作用，并探索可能的新兴现象。 These research activities help develop a critical understanding of the fundamental photophysical, electrical transport properties, and the intriguing carrier-phonon interactions in this unique class of materials, which will not aim engineering improved photovoltaics or light-emitting diodes, but also help unlock new technical potentials from MHPs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader影响审查标准。