Exploring Spin-Orbital Coupling Effects: 3D to 2D Perovskite Solar Cells

非技术：有机-无机卤化物钙钛矿已经显示出太阳能电池的前景，其性能接近商用设备。考虑到柔性设备的低成本制造前景，这些设备可能会改变太阳能的格局。进一步的进展需要对结构-性质关系有更深的理解。该项目计划研究钙钛矿的基本性质。重点将放在自旋轨道耦合上，它连接了光学、电学和磁性。这些研究将结合材料加工、设备工程和动态测量。目标是对这些材料有更深入的了解，并提高钙钛矿太阳能电池的性能。该项目将通过外展和新课程影响研究生和本科生。PI还将招收来自科学和工程领域代表性不足群体的学生。技术方面：该项目将通过实验研究从3D到2D设计的有机-无机杂化卤化物钙钛矿太阳能电池的自旋轨道耦合（SOC）效应。近年来钙钛矿太阳能电池的成功源于其高吸收系数，激发态的有效解离，以及在自旋轨道耦合框架内同时发生的优越载流子输运。然而，为了进一步推动钙钛矿太阳能电池的研究和发展，需要深入的基础研究，揭示激发态和载流子动力学中更深层次的结构-性能关系。本项目的目的是了解掺杂、结构有序和外部刺激下的SOC效应。本研究的目的是揭示调整SOC效应、Rashba效应和自旋混合的潜在机制，为进一步推进有机-无机杂化卤化物钙钛矿的光伏功能提供创新机制。该项目计划实现三个关键目标：(i)揭示掺杂可调SOC的创新机制，（ii）通过Rashba效应探索SOC对直接/间接能带跃迁的影响，以及（iii）阐明在3D到2D混合卤化物钙钛矿设计中SOC对暗态和亮态自旋混合的影响。本研究将整合材料加工、器件工程和实验测量三个主要的跨学科努力，以探索SOC效应。材料加工工作将制备具有不同极化和结构对称/不对称的3D和2D钙钛矿，为探索SOC效应提供基础平台。设备工程工作将从3D到2D结构制备最先进的钙钛矿太阳能电池。实验测量将包括磁场效应、光偏振调制光电流/光致发光、时间分辨光致发光光谱和泵浦探针瞬态吸收，以揭示在引入掺杂、结构有序和外部刺激的情况下，控制混合卤化物钙钛矿从3D到2D设计中SOC效应的潜在机制。总体而言，该项目将阐明控制SOC效应、Rashba效应和自旋混合的关键因素，从而从根本上推进钙钛矿光伏器件的发展。该奖项反映了美国国家科学基金会的法定使命，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:Organic-inorganic halide perovskites have shown promise for solar cells with performance approaching that of commercially available devices. These devices could transform the solar energy landscape, given the promise for low-cost manufacturing of flexible devices. Further advances require a deeper understanding of structure-property relationships. This project plans to study the fundamental properties of perovskites. The focus will be on spin-orbit coupling, which connects optical, electrical, and magnetic properties. These studies will combine materials processing, device engineering, and dynamic measurements. The goal is to achieve a deeper understanding of these materials and advance the performance of perovskite solar cells. The project will impact graduate and undergraduate students through outreach and new curriculum. The PI will also recruit and involve students from underrepresented groups in science and engineering.Technical:The proposed project will experimentally investigate spin-orbital coupling (SOC) effects in organic-inorganic hybrid halide perovskite solar cells ranging from 3D to 2D designs. The recent success of perovskite solar cells stems from the high absorption coefficient, efficient dissociation of excited states, and superior carrier transport that simultaneously occur within spin-orbital coupling framework. However, in-depth fundamental studies are timely needed to further advance the research and development of perovskite solar cells by revealing deeper structure-property relationships in both excited state and carrier dynamics. The objective of this project is to understand the SOC effects under doping, structural ordering, and external stimuli. The goal of this research is to reveal the underlying mechanisms to tune SOC effects, Rashba effects, and spin mixing towards providing innovative mechanisms to further advance photovoltaic functionalities in organic-inorganic hybrid halide perovskites. This project plans to achieve three critical goals: (i) reveal innovative mechanisms of doping-tunable SOC, (ii) explore SOC effects on direct/indirect band transitions through Rashba effect, and (iii) elucidate SOC effects on spin mixing between dark and bright states, in hybrid halide perovskites ranging from 3D to 2D designs. The proposed research will be performed by integrating three major interdisciplinary efforts from materials processing, device engineering, and experimental measurements, to explore SOC effects. The materials processing effort will prepare both 3D and 2D perovskites with different polarizations and structural symmetries/asymmetries to provide a fundamental platform to explore SOC effects. The device engineering effort will prepare state-of-the-art perovskite solar cells from 3D to 2D structures. The experimental measurements will include magnetic field effects, light polarization-modulated photocurrent/photoluminescence, time-resolved photoluminescence spectroscopy, and pump-probe transient absorption to reveal underlying mechanisms towards controlling SOC effects in hybrid halide perovskites ranging from 3D to 2D designs upon introducing doping, structural ordering, and external stimuli. Overall, the project will elucidate the key factors of controlling SOC effects, Rashba effects, and spin mixing towards fundamentally advancing perovskite photovoltaic devices.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.