Catalyst Project: Age and temperature-dependent millimeter-wave charge carrier dynamics in hybrid perovskite films

催化剂项目为历史上的黑人学院和大学（HBCU）提供支持，致力于建立教师的研究能力，以加强科学，技术，工程和数学（STEM）本科教育和研究。预计该奖项将进一步提高教师的研究能力，改善研究和教学机构，并参与本科生的研究经验。该奖项授予北卡罗来纳州中央大学，支持教师和本科生的研究经验，调查老化和温度对混合有机-无机钙钛矿的影响，以预测载流子密度。具体而言，该项目旨在利用高通量测试和机器学习算法进行数据分析，以了解有机金属卤化物钙钛矿老化相关的稳定性和降解的原因。三维形式的钙钛矿是一种非常有吸引力的材料，用于场效应晶体管（FET），发光二极管（LED），光和辐射检测，闪烁，生物化学应用，并具有直接的工业应用于制氢。 由于单分子甲基卤化铅铵（MAL 3 I）及其阳离子工程变体的（陷阱辅助）重组趋势可以使用时间分辨微波电导率（TRMC）测量直接测量，该项目旨在使用NCCU开发的自由空间时间分辨毫米波电导率装置（TR-mmWC），观察MAL 3 I及其结构变体在不同暴露温度下的年龄峰电压和非辐射年龄复合衰减趋势。 实验数据的收集和分析将有助于告知两个问题：（1）样品是否会随着时间的推移而产生浅缺陷，以便随着老化而更好地传输电荷，或者相反的过程是否成立？（2）在有机（MA）-无机（L3 I）杂化体系中，正光电导峰和负光电导峰是如何表现的？这些研究有可能揭示电磁相互作用与材料介电性质和电导率的频率依赖性，以及在大温度范围内系统收集扫频吸收剖面，演示了毫米级电荷动力学特性-在不同的温度下，波的频率会随着年龄的增长而变化。该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准。

Catalyst Projects provide support for Historically Black Colleges and Universities (HBCU) to work towards establishing research capacity of faculty to strengthen science, technology, engineering, and mathematics (STEM) undergraduate education and research. It is expected that the award will further the faculty member's research capability, improve research and teaching at the institution, and involve undergraduate students in research experiences. This award to North Carolina Central University supports faculty and undergraduate research experiences investigating the effects of aging and temperature on hybrid organic-inorganic perovskites to predict charge carrier density. Specifically, the project seeks to utilize high-throughput testing and a machine learning algorithm for data analyses to understand aging related stability and the causes of degradation of organometallic halide perovskites.Perovskite in 3-D form is a very attractive material for applications such as a field-effect transistor (FET), light-emitting diodes (LED), photo- and radiation detection, scintillation, biochemical applications, and has direct industrial application for hydrogen production. Since monomolecular (trap-assisted) recombination trends in methylammonium lead-halide (MAL3I) and its cation engineered variants can be directly measured using the time-resolved microwave conductivity (TRMC) measurements, this project aims to use a free-space time-resolved millimeter-wave conductivity apparatus (TR-mmWC), developed at NCCU, to observe the age-peak voltage and non-radiative age-recombination decay trends in MAL3I and its structural variants at different exposure temperature regimes. The experimental data collection and analysis will help inform two questions: (1) Does the sample develop shallow defects over time for a better charge transport with aging, or does the reverse process hold? and (2) How do the positive peak and negative photoconductivity behave in an hybrid organic (MA) – inorganic (L3I) system? These studies have the potential to reveal the frequency dependence of electromagnetic interaction with material dielectric properties and conductivity, and the systematical collection of frequency-swept absorption profiles in a large temperature range, demonstrating how the charge dynamical properties at millimeter-wave frequencies change by age at different temperatures.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.