講座題目：3維和2維鈣鈦礦光伏和發(fā)光器件中自旋軌道耦合效應(yīng)

報 告 人：胡斌

時 　 間：2019年12月16日(周一)16:00-17:30

地 　 點：中關(guān)村校區(qū)研究生教學樓101報告廳

主辦單位：研究生院、材料學院

報名方式：登錄北京理工大學微信企業(yè)號---第二課堂---課程報名中選擇“【百家大講堂】第296期：3維和2維鈣鈦礦光伏和發(fā)光器件中自旋軌道耦合效應(yīng)”

【主講人簡介】

  胡斌,，美國田納西大學材料科學與工程系的終身教授和博士導師,，同時兼任美國能源部橡樹嶺國家實驗室的客座研究員，臺灣成功大學的客座教授,。主要研究方向包括：有機自旋光電子學,、鹵化物鈣鈦礦及有機太陽能電池和高分子熱電轉(zhuǎn)換,、激發(fā)態(tài)和電荷相干行為。在Nature Materials, Nature Communications, Advanced Materials, Advanced Energy Materials, Advanced Functional Materials, JACS, ACS Nano, Nano Energy, Small, Scientific Report 上發(fā)表了一系列很有影響力的文章,。目前在有機光電子學,、有機自旋光電子學、鈣鈦礦光伏-發(fā)光-激光研究方面共發(fā)表論文160多篇,，他引次數(shù)超過5000,。

【講座信息】

  有機-無機半導體鈣鈦礦已顯示出非常誘人的室溫磁光響應(yīng)，出色的光伏性能,，顏色可調(diào)的發(fā)光特性和低閾值激光特性,，從而成為新興的多功能材料。另一方面,，ABX3結(jié)構(gòu)的有機-無機半導體鈣鈦礦在電致極化半導體材料框架內(nèi)具有很強的自旋-軌道耦合特性,。通常，自旋軌道耦合可以產(chǎn)生三個主要結(jié)果：（i）Rashba效應(yīng),，（ii）不同狀態(tài)之間的自旋混合,，（iii）在這種混合鈣鈦礦中的電磁耦合。應(yīng)該指出的是,，有機-無機半導體鈣鈦礦表現(xiàn)出明顯的軌道動量,，與自旋動量形成強自旋軌道耦合。因此,，使用軌道動量提供了一種獨特的機制來控制這種混合鈣鈦礦中的光電特性,。我們發(fā)現(xiàn)，從3維鈣鈦礦轉(zhuǎn)變?yōu)?維鈣鈦礦會導致從短距離自旋-自旋相互作用到遠距離軌道-軌道相互作用,。另一方面,，我們觀察到自旋軌道耦合可以通過晶界極化改變，從而導致一種方便的方法來通過摻雜和機械應(yīng)力來調(diào)整自旋軌道耦合,。而且,，使用自旋-軌道耦合提出了一種實用的方法，以消除鈣鈦礦LED中暗態(tài)的發(fā)光損失,?？偠灾緢蟾鎸⒂懻搹?維到2維鈣鈦礦的光伏和發(fā)光器件所涉及的自旋軌道耦合效應(yīng),。

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.