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(bào) 告 人：胡斌

時(shí) 　 間：2019年12月16日(周一)16:00-17:30

地 　 點(diǎn)：中關(guān)村校區(qū)研究生教學(xué)樓101報(bào)告廳

主辦單位：研究生院,、材料學(xué)院

報(bào)名方式：登錄北京理工大學(xué)微信企業(yè)號(hào)---第二課堂---課程報(bào)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(jiǎn)介】

  胡斌,，美國田納西大學(xué)材料科學(xué)與工程系的終身教授和博士導(dǎo)師,，同時(shí)兼任美國能源部橡樹嶺國家實(shí)驗(yàn)室的客座研究員,，臺(tái)灣成功大學(xué)的客座教授,。主要研究方向包括：有機(jī)自旋光電子學(xué),、鹵化物鈣鈦礦及有機(jī)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(jī)光電子學(xué),、有機(jī)自旋光電子學(xué)、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(jī)-無機(jī)半導(dǎo)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(jī)-無機(jī)半導(dǎo)體鈣鈦礦在電致極化半導(dǎo)體材料框架內(nèi)具有很強(qiáng)的自旋-軌道耦合特性,。通常，自旋軌道耦合可以產(chǎn)生三個(gè)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(jī)-無機(jī)半導(dǎo)體鈣鈦礦表現(xiàn)出明顯的軌道動(dòng)量,，與自旋動(dòng)量形成強(qiáng)自旋軌道耦合。因此,，使用軌道動(dòng)量提供了一種獨(dú)特的機(jī)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(huì)導(dǎo)致從短距離自旋-自旋相互作用到遠(yuǎn)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(dǎo)致一種方便的方法來通過摻雜和機(jī)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(shí)用的方法，以消除鈣鈦礦LED中暗態(tài)的發(fā)光損失?？偠灾?，本報(bào)告將討論從3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.