Chao Roark, Heki Larry K, Mills Wesley K, Schuller Jon A
Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, United States.
Materials Department, University of California, Santa Barbara, California 93106, United States.
ACS Appl Opt Mater. 2025 Mar 14;3(3):737-742. doi: 10.1021/acsaom.4c00529. eCollection 2025 Mar 28.
Recently, layered 2D hybrid organic-inorganic perovskites (HOIPs) like butylammonium lead iodide (BAPbI) have been shown to exhibit ultrabright out-of-plane-oriented magnetic dipole (MD) photoluminescence (PL) arising from self-trapped excitons (STEs). The MD emission, however, has considerable spectral overlap with the dominant in-plane-oriented electric dipole (ED) transitions, making it difficult to interrogate STE properties. Here, we theoretically investigate opportunities to use Mie resonator dimers to selectively enhance the MD emission through the Purcell effect. We calculate relative MD and ED Purcell enhancements at dimer center as well as average values across the dimer geometry. We show that the selective enhancement is excellent at the dimer center enabling nearly pure MD emission (96%) at the MD emission peak (540 nm) as well as predominant MD emission (up to 77%) across the entire integrated spectrum (500-600 nm). We subsequently show, however, that away from the dimer center, Purcell enhancement of the relatively weak out-of-plane ED transitions competes with MD enhancements, reducing the branching ratio (73% at the MD emission peak, 39% spectrally integrated). Lastly, we calculate how the Mie resonator dimer modifies the PL spectra and emitter radiation pattern. Notably, for volume-averaged dipoles, both MD and ED emissions are mediated via the dimer, producing a single donut-beam-like radiation pattern across the entire emission spectrum. Our results clarify the potential for achieving "pure" MD emission from 2D HOIPs via simple Mie resonator Purcell enhancements and highlight the importance of designing nanophotonic structures that can maintain desired selective enhancements away from high-symmetry points.
最近，像丁基碘化铅（BAPbI）这样的层状二维有机-无机杂化钙钛矿（HOIPs）已被证明表现出由自陷激子（STE）产生的超亮面外取向磁偶极（MD）光致发光（PL）。然而，MD发射与主要的面内取向电偶极（ED）跃迁有相当大的光谱重叠，这使得难以研究STE的性质。在这里，我们从理论上研究了利用米氏谐振器二聚体通过珀塞尔效应选择性增强MD发射的机会。我们计算了二聚体中心处MD和ED的相对珀塞尔增强以及整个二聚体几何结构上的平均值。我们表明，在二聚体中心处选择性增强效果极佳，在MD发射峰（540 nm）处能够实现近乎纯的MD发射（96%），并且在整个积分光谱（500 - 600 nm）范围内主要为MD发射（高达77%）。然而，我们随后表明，在远离二聚体中心的地方，相对较弱的面外ED跃迁的珀塞尔增强与MD增强相互竞争，降低了分支比（在MD发射峰处为73%，光谱积分后为39%）。最后，我们计算了米氏谐振器二聚体如何改变PL光谱和发射体辐射模式。值得注意的是，对于体积平均偶极子，MD和ED发射均通过二聚体介导，在整个发射光谱上产生单个甜甜圈光束状辐射模式。我们的结果阐明了通过简单的米氏谐振器珀塞尔增强从二维HOIPs实现“纯”MD发射的潜力，并强调了设计能够在远离高对称点处保持所需选择性增强的纳米光子结构的重要性。
