ERI: Theory and Simulation of Photoexcitation Dynamics in 2-Dimensional Materials for Solar Energy Harvesting

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。以环境可持续的方式满足世界不断增长的人口日益增长的能源需求，是当今社会面临的最重要的科学挑战之一。一种这样的方法是利用来自阳光的能量；然而，目前用于捕捉太阳能的材料制造成本高，效率相对较低。为了帮助高效地收集太阳能以进行能量转换，该项目旨在确定两种类型的二维材料的特定性质如何能够吸收太阳能。最先进的计算方法被用来在原子及其电子水平上模拟这些能量转换过程。该项目融合了材料科学、工程学和计算物理化学的知识。这项研究的结果将提高我们对目前正在进行实验研究的材料使用太阳能收集装置的理解，并为提高其效率提供见解。Trivedi博士的研究计划与教育部分相结合，以激励本科生和研究生追求科学、技术和工程方面的职业。二维纳米多孔材料显示出丰富的光物理特性，这些特性控制着材料内部的激发动力学，从而产生高效的电荷和能量的产生和传输。然而，最近关于界面、缺陷和掺杂对用于太阳能收集装置的平面纳米多孔材料的电荷和能量动力学以及它们的功率转换效率的影响的实验已经暴露出一些基本的问题。具体地说，激子猝灭和不受欢迎的电荷俘获对这些事件的影响尚不确定。本项目将研究两种特定类型的纳米结构中涉及激子产生和传输以及光激发后电荷分离的非平衡过程：(I)以Cu3HHTT2 MOF为代表的具有蜂窝状片状结构的2D共轭MOF和(Ii)单分子膜的三S三嗪基碳氮化物。使用混合量子经典方法和非绝热分子动力学的组合，这项计算研究将提供光激发动力学的详细的原子水平描述。研究尺寸、界面、缺陷和掺杂对材料捕光性能的影响可以通过两个目标来理解：(1)用电子结构理论阐明界面对电荷和能量传递的影响；(2)研究激子产生和输运以及界面电荷分离所涉及的非平衡现象。通过计算确定这些平面纳米材料内部和界面上的电荷和能量动力学，将为它们在太阳能收集、传感、成像和其他先进技术设备中的最佳使用提供重要的见解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Meeting the increasing energy demands of the world’s growing population in environmentally sustainable ways is among the most important scientific challenges facing society today. One such approach is to tap into the energy from sunlight; however, current materials used to capture solar energy are costly to manufacture and relatively inefficient. To contribute to efficient harvesting of solar light for energy conversion processes, this project is designed to determine how specific properties of two types of 2-dimensional materials enable absorption of solar energy. State-of-the-art computational approaches are used to model these energy conversion processes at the level of atoms and their electrons. The project integrates the knowledge of material science, engineering, and computational physical chemistry. The results of this research will improve our understanding of materials currently under experimental investigation for use of solar energy harvesting devices and provide insights to improve their efficiency. Dr. Trivedi’s research program is integrated with an educational component to inspire undergraduate and graduate students to pursue careers in science, technology, and engineering.Two dimensional nanoporous materials displays a rich array of photophysical properties that govern excitation dynamics within the material resulting in efficient charge and energy generation and transport. However, fundamental questions have emerged from recent experiments regarding the influence of interface, defects, and dopants on the charge and energy dynamics of planar nanoporous materials and their power conversion efficiencies used in solar energy harvesting devices. Specifically, how exciton quenching and undesired charge trapping contribute to these events is uncertain. This project will investigate nonequilibrium processes involved in exciton generation and transport, and in charge separation following photoexcitation in two specific types of nanostructures: (i) Cu3HHTT2 MOF as a representative of a family of 2D - conjugated MOFs with honeycomb-like sheet structures and (ii) monolayer of tri-s-triazine-based graphitic carbon nitride. Using a combination of mixed quantum-classical approaches and nonadiabatic molecular dynamics this computational research will provide a detailed, atomistic level description of the photoexcitation dynamics. The investigation of influence of dimensionality, interfaces, defects, and dopants on the material’s light harvesting performance will be understood by pursuing two objectives, to (i) elucidate the influence of interface on charge and energy transfer using electronic structure theory and (ii) investigate nonequilibrium phenomena involved in exciton generation and transport followed by charge separation at the interface. Computational determination of the charge and energy dynamics within and at interfaces of these planar nanoscale materials will provide essential insights for their optimal use in devices for solar energy harvesting, sensing, imaging and other advanced technologies.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.