title: Electron-Phonon Scattering in Atomically Thin 2D Perovskites.
abstract: Two-dimensional (2D) atomically thin perovskites with strongly bound excitons are highly promising for optoelectronic applications. However, the nature of nonradiative processes that limit the photoluminescence (PL) efficiency remains elusive. Here, we present time-resolved and temperature-dependent PL studies to systematically address the intrinsic exciton relaxation pathways in layered (C4H9NH3)2(CH3NH3)n-1PbnI3n+1(n = 1, 2, 3) structures. Our results show that scatterings via deformation potential by acoustic and homopolar optical phonons are the main scattering mechanisms for excitons in ultrathin single exfoliated flakes, exhibiting a Tγ(γ = 1.3 to 1.9) temperature dependence for scattering rates. We attribute the absence of polar optical phonon and defect scattering to efficient screening of Coulomb potential, similar to what has been observed in 3D perovskites. These results establish an understanding of the origins of nonradiative pathways and provide guidelines for optimizing PL efficiencies of atomically thin 2D perovskites.
authors.affiliation: Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Libai
authors.initials: L
authors.lastname: Huang
keywords: carrier−phonon scattering; exciton dynamics; low-dimensional systems; perovskite