讲座题目：3维和2维钙钛矿光伏和发光器件中自旋轨道耦合效应

报 告 人：胡斌

时 　 间：2019年12月16日(周一)16:00-17:30

地 　 点：中关村校区研究生教学楼101报告厅

主办单位：研究生院、材料学院

报名方式：登录北京理工大学微信企业号---第二课堂---课程报名中选择“【百家大讲堂】第296期：3维和2维钙钛矿光伏和发光器件中自旋轨道耦合效应”

【主讲人简介】

  胡斌，美国田纳西大学材料科学与工程系的终身教授和博士导师，同时兼任美国能源部橡树岭国家实验室的客座研究员，台湾成功大学的客座教授。主要研究方向包括：有机自旋光电子学、卤化物钙钛矿及有机太阳能电池和高分子热电转换、激发态和电荷相干行为。在Nature Materials, Nature Communications, Advanced Materials, Advanced Energy Materials, Advanced Functional Materials, JACS, ACS Nano, Nano Energy, Small, Scientific Report 上发表了一系列很有影响力的文章。目前在有机光电子学、有机自旋光电子学、钙钛矿光伏-发光-激光研究方面共发表论文160多篇，他引次数超过5000。

【讲座信息】

  有机-无机半导体钙钛矿已显示出非常诱人的室温磁光响应，出色的光伏性能，颜色可调的发光特性和低阈值激光特性，从而成为新兴的多功能材料。另一方面，ABX3结构的有机-无机半导体钙钛矿在电致极化半导体材料框架内具有很强的自旋-轨道耦合特性。通常，自旋轨道耦合可以产生三个主要结果：（i）Rashba效应，（ii）不同状态之间的自旋混合，（iii）在这种混合钙钛矿中的电磁耦合。应该指出的是，有机-无机半导体钙钛矿表现出明显的轨道动量，与自旋动量形成强自旋轨道耦合。因此，使用轨道动量提供了一种独特的机制来控制这种混合钙钛矿中的光电特性。我们发现，从3维钙钛矿转变为2维钙钛矿会导致从短距离自旋-自旋相互作用到远距离轨道-轨道相互作用。另一方面，我们观察到自旋轨道耦合可以通过晶界极化改变，从而导致一种方便的方法来通过掺杂和机械应力来调整自旋轨道耦合。而且，使用自旋-轨道耦合提出了一种实用的方法，以消除钙钛矿LED中暗态的发光损失。总而言之，本报告将讨论从3维到2维钙钛矿的光伏和发光器件所涉及的自旋轨道耦合效应。

Organic-inorganic semiconducting perovskites have demonstrated very attractive room-temperature magneto-optical response, remarkable photovoltaic actions, color-tunable light-emitting properties, and low-threshold lasing actions, to become emerging multifunctional materials. On the other hand, organic-inorganic semiconducting perovskites possess a strong spin-orbital coupling within electrically polarizable semiconducting framework consisting of organic and inorganic components in ABX3 structure. In general, spin-orbital coupling can generate three major outcomes: (i) Rashba effect, (ii) spin mixing between different states, and (iii) electric-magnetic coupling in such hybrid perovskites. It should be pointed out that organic-inorganic semiconducting perovskites show significant orbital momentum to form a strong spin-orbital coupling with spin momentum. Therefore, using orbital momentum presents a unique mechanism to control the optoelectronic properties in such hybrid perovskites. We found that changing from 3D to 2D perovskites causes from short-range spin-spin interaction to long-distance orbital-orbital interaction, leading to distinct SOC effects on the populations on dark and bright states towards developing photovoltaic and light-emitting actions. On the other hand, we observed that the spin-orbital coupling can be changed by grain boundary polarization, leading to a convenient method to tune the spin-orbital coupling through doping and mechanical stress. Moreover, using the spin-orbital coupling presents a practical approach to remove the light-emitting loss from dark states in perovskite LEDs. In summary, this presentation will discuss the spin-orbital coupling effects involved in photovoltaic and light-emitting devices from 3D to 2D perovskites.