以掃描穿隧顯微術探討鈣鈦礦太陽能材料表面的拉什巴效應

Abstract

太陽能電池這個研究課題的討論在近幾年的熱絡程度可見一斑，而作為太陽能電池表現性能的指標，能量轉換效率值(PCE)的突破是研究學者們一直以來所追求的目標。其中，有機–無機混態的鈣鈦礦材料在這項數值上展現了可觀的進步幅度，背後諸多的特殊物理性質也吸引了研究者的注意。甲基胺溴化鉛，作為混態鈣鈦礦材料的一員，具有的不僅僅是在作為太陽能電池材料上佔據優勢的光電特性，其本質上的強自旋軌道藕荷更讓它成為自旋電子學上的研究材料之一。 該材料的表面原子及電子結構正是這些特性與現象的關鍵成因，然而這其中依然有諸多揣想及未被證明的地方。我們透過剖面掃描穿隧式電子顯微鏡與能譜術，建立出甲基胺溴化鉛在表面照光之下的完整結電子結構。另外，從實驗結果分析來看，表面電子的能量與動量關係確實符合自旋軌道藕荷作用下的趨勢。

Solar cell has become prevailing these few years and achieving upmost power conversion efficiency (PCE) is the ultimate goal scientists seek for. Among tons of candidates, organic-inorganic hybrid perovskite (OIHP) shows its amazingly progressive pace in PCE, besides which there are also other unique characters of this material that attract researchers’ attention. MAPbBr3, as a member of the OIHP family, is not only a promising material in solar cell, but its intrinsic strong spin-orbit interaction also makes it interesting in spintronics application. It is its surface electronic characteristics that makes it such anticipated, but a more detailed insight is still blurred, and the actual mechanism is yet in argument. With the aid of Cross-section Scanning Tunneling Microscopy/Spectroscopy (XSTM/S), we reveal a complete scheme of the surface electronic structure of MAPbBr3 upon laser irradiation, and further demonstrate the considerable influence that spin-orbit interaction exerts on it.