<br>单个 CsPbBr3 钙钛矿量子点无需外部磁场即可实现圆偏振发光,ACS Nano

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单个 CsPbBr3 钙钛矿量子点无需外部磁场即可实现圆偏振发光
ACS Nano ( IF 15.8 ) Pub Date : 2024-06-21 , DOI: 10.1021/acsnano.4c04392
Virginia Oddi _{1,

2} , Chenglian Zhu _{2,

3} , Michael A Becker ₁ , Yesim Sahin _{2,

3} , Dmitry N Dirin _{2,

3} , Taehee Kim _{2,

3} , Rainer F Mahrt ₁ , Jacky Even ₄ , Gabriele Rainò _{2,

3} , Maksym V Kovalenko _{2,

3} , Thilo Stöferle ₁

Affiliation

卤化铅钙钛矿量子点 (QD) 是最新一代的胶体 QD 系列，具有出色的光学特性，目前被用作经典光源和量子光源。它们大多数相当特殊的性质都与带边态奇特的激子精细结构有关，它可以支持独特的明亮三线态激子。明亮的三重态激子的简并性随着毫电子伏量级的能量分裂而升高，这可以通过低温下单个量子点的光致发光（PL）测量来解决。每个明亮的激子精细结构态（FSS）都表现出主要的线性偏振，符合基于单一晶体场、交换相互作用和形状各向异性的几个理论模型。在这里，我们通过研究单个 CsPbBr ₃中激子精细结构的四个斯托克斯参数表明，除了高度的线性极化之外，即使没有外部磁场，单个激子 FSS 也可以表现出不可忽略的圆极化程度。通过斯托克斯偏振测量的量子点。我们观察到圆偏振度高达~38%，这是使用传统偏振技术无法检测到的。此外，我们发现精细结构三重态流形内从左旋圆偏振到右旋圆偏振的一致转变，这是在磁场相关实验中观察到的。我们的光学研究为激子精细结构的性质提供了更深入的见解，从而推动了对此类量子点独特光物理性质的还不完整的理解，以利于未来在手性量子光学中的应用。

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Circularly Polarized Luminescence Without External Magnetic Fields from Individual CsPbBr3 Perovskite Quantum Dots

Lead halide perovskite quantum dots (QDs), the latest generation of the colloidal QD family, exhibit outstanding optical properties, which are now exploited as both classical and quantum light sources. Most of their rather exceptional properties are related to the peculiar exciton fine-structure of band-edge states, which can support unique bright triplet excitons. The degeneracy of the bright triplet excitons is lifted with energetic splitting in the order of millielectronvolts, which can be resolved by the photoluminescence (PL) measurements of single QDs at cryogenic temperatures. Each bright exciton fine-structure-state (FSS) exhibits a dominantly linear polarization, in line with several theoretical models based on the sole crystal field, exchange interaction, and shape anisotropy. Here, we show that in addition to a high degree of linear polarization, the individual exciton FSS can exhibit a non-negligible degree of circular polarization even without external magnetic fields by investigating the four Stokes parameters of the exciton fine-structure in individual CsPbBr₃ QDs through Stokes polarimetric measurements. We observe a degree of circular polarization up to ∼38%, which could not be detected by using the conventional polarimetric technique. In addition, we found a consistent transition from left- to right-hand circular polarization within the fine-structure triplet manifold, which was observed in magnetic-field-dependent experiments. Our optical investigation provides deeper insights into the nature of the exciton fine structures and thereby drives the yet-incomplete understanding of the unique photophysical properties of this class of QDs for the benefit of future applications in chiral quantum optics.

更新日期：2024-06-21

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