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Dopant-Induced Slow Spin Relaxation in CsPbBr3 Perovskite Nanocrystals
ACS Energy Letters ( IF 19.3 ) Pub Date : 2022-11-07 , DOI: 10.1021/acsenergylett.2c01901
Hui Cheng 1, 2 , Jing Leng 2 , Fengke Sun 2 , Shengli Zhao 2 , Jianbo Tang 2 , Kaifeng Wu 2 , Jiming Bian 1 , Shengye Jin 2
Affiliation  

Lead halide perovskites comprise a class of materials holding great promise for spin-related applications due to their strong spin–orbital coupling (SOC) effect. However, the strong SOC also shortens the lifetime of spin states and thus limits their further application. Herein we take Bi-doped CsPbBr3 perovskite nanocrystals (NCs) as an example material to study how metal doping can affect the spin-relaxation process, by using circularly polarized transient absorption (TA) spectroscopy. We demonstrate that in undoped CsPbBr3 NCs the spin relaxation is governed by the electron–hole exchange (EHE) mechanism and in doped NCs the Bi-dopants significantly slow down the spin relaxation by creating an ultrafast (∼0.13 ps) hole trapping process and thus disturbing the EHE spin de-coherent process. By tuning the Bi-doping ratio, the spin-relaxation time in doped NCs is prolonged to ∼24.6 ps, much longer than that (∼4.4 ps) in undoped NCs. Our finding suggests that doping a metal element is an effective way to tune the spin relaxation in perovskites NCs and likely also in many other types of quantum-confined NCs.

中文翻译:

CsPbBr3 钙钛矿纳米晶体中掺杂剂诱导的慢速自旋弛豫

卤化铅钙钛矿包括一类材料,由于其强大的自旋轨道耦合 (SOC) 效应,在自旋相关应用中具有广阔前景。然而,强SOC也缩短了自旋态的寿命,从而限制了它们的进一步应用。在此,我们以 Bi 掺杂的 CsPbBr 3钙钛矿纳米晶体 (NCs) 为示例材料,通过使用圆偏振瞬态吸收 (TA) 光谱研究金属掺杂如何影响自旋弛豫过程。我们证明在未掺杂的 CsPbBr 3NCs 的自旋弛豫受电子-空穴交换 (EHE) 机制控制,在掺杂的 NCs 中,Bi 掺杂剂通过产生超快 (~0.13 ps) 空穴捕获过程显着减缓自旋弛豫,从而扰乱 EHE 自旋去-连贯的过程。通过调整 Bi 掺杂比,掺杂 NC 中的自旋弛豫时间延长至 ~24.6 ps,远长于未掺杂 NC 中的自旋弛豫时间(~4.4 ps)。我们的发现表明,掺杂金属元素是调节钙钛矿 NC 中自旋弛豫的有效方法,也可能适用于许多其他类型的量子限制 NC。
更新日期:2022-11-07
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