2022/08/16 by Tong Jiang, Jiang, Tong, Jiajun Ren +3
Chemistry · Engineering · Physics and Astronomy · #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Perovskite Materials and Applications #Photochemistry and Electron Transfer Studies #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.2208.07505
openalex publication_date 2022/08/16 · openalex created_date 2022/10/05 · openalex updated_date 2026/07/28
Exciton coherence length (ECL) is an essential concept to characterize the nature of exciton in molecular aggregates for photosynthesis, organic photovoltaics, and light-emitting diodes. ECL has been defined in a number of ways through the variance or purity of the electronic reduced density matrix. However, we find that these definitions fail to present a monotonic relationship with respect to the exciton radiative decay efficiency as it should be when exciton-phonon couplings are taken into accounts. We propose a unified definition of ECL by virtue of sum rule of oscillator strengths. Using the numerically accurate time-dependent matrix product states formalism applied to Frenkel-Holstein models for molecular aggregates in both one- and two-dimensional system, we find our ECL definition exhibits a monotonic relationship with respect to the radiative efficiency and can serve as an efficient and unified description for exciton coherence. We further predict that the two-dimensional aggregates can display maximum superradiance enhancement (SRE) at finite temperature, different from the previous knowledge of SRE-1/T behavior.