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

非技术性：有机-无机卤化物钙钛矿已经显示出在太阳能电池方面的前景，其性能接近商业设备。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，它将光学、电学和磁性联系在一起。这些研究将结合材料加工、设备工程和动态测量。目的是加深对这些材料的了解，提高钙钛矿型太阳能电池的性能。该项目将通过外展和新课程影响研究生和本科生。PI还将招募和吸收科学和工程领域代表不足的群体的学生。技术：拟议的项目将对有机-无机杂化卤化物钙钛矿太阳能电池中的自旋轨道耦合(SOC)效应进行实验研究，范围从3D到2D设计。钙钛矿型太阳能电池最近的成功源于高吸收系数、有效的激发态解离和优越的载流子传输，这些都同时发生在自旋-轨道耦合框架内。然而，通过揭示激发态和载流子动力学中更深层次的结构-性质关系，及时需要深入的基础研究来进一步推进钙钛矿型太阳能电池的研究和开发。本项目的目标是了解掺杂、结构有序和外部刺激下的SOC效应。这项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，以提供创新的机制，进一步提高有机-无机杂化卤化物钙钛矿的光伏功能。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SOC对从3D到2D设计的混合卤化物钙钛矿暗和亮态之间自旋混合的影响。这项拟议的研究将通过整合材料加工、设备工程和实验测量三个主要跨学科的努力来进行，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性/不对称性的3D和2D钙钛矿，为探索SOC效应提供基本平台。这项设备工程工作将使最先进的钙钛矿型太阳能电池从3D结构发展到2D结构。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-探测瞬时吸收，以揭示引入掺杂、结构有序和外部刺激时控制从3D到2D设计的混合卤化物钙钛矿中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，以从根本上推动钙钛矿型光伏器件的发展。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。

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.