Bennecke Wiebke, Windischbacher Andreas, Schmitt David, Bange Jan Philipp, Hemm Ralf, Kern Christian S, D'Avino Gabriele, Blase Xavier, Steil Daniel, Steil Sabine, Aeschlimann Martin, Stadtmüller Benjamin, Reutzel Marcel, Puschnig Peter, Jansen G S Matthijs, Mathias Stefan
I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010, Graz, Austria.
Nat Commun. 2024 Feb 28;15(1):1804. doi: 10.1038/s41467-024-45973-x.
Excitons are realizations of a correlated many-particle wave function, specifically consisting of electrons and holes in an entangled state. Excitons occur widely in semiconductors and are dominant excitations in semiconducting organic and low-dimensional quantum materials. To efficiently harness the strong optical response and high tuneability of excitons in optoelectronics and in energy-transformation processes, access to the full wavefunction of the entangled state is critical, but has so far not been feasible. Here, we show how time-resolved photoemission momentum microscopy can be used to gain access to the entangled wavefunction and to unravel the exciton's multiorbital electron and hole contributions. For the prototypical organic semiconductor buckminsterfullerene (C), we exemplify the capabilities of exciton tomography and achieve unprecedented access to key properties of the entangled exciton state including localization, charge-transfer character, and ultrafast exciton formation and relaxation dynamics.
激子是一种相关多粒子波函数的体现，具体由处于纠缠态的电子和空穴组成。激子在半导体中广泛存在，并且是有机半导体和低维量子材料中的主要激发态。为了在光电子学和能量转换过程中有效利用激子的强光响应和高可调性，获取纠缠态的完整波函数至关重要，但迄今为止这并不可行。在此，我们展示了如何利用时间分辨光发射动量显微镜来获取纠缠波函数，并解开激子的多轨道电子和空穴贡献。对于典型的有机半导体巴基球（C），我们例证了激子断层成像的能力，并以前所未有的方式获取了纠缠激子态的关键性质，包括局域化、电荷转移特性以及超快激子形成和弛豫动力学。
