Photoluminescence of excitons and biexcitons in (C₄H₉NH₃)₂PbBr₄ crystals under high excitation density

Abstract

Optical properties in (C4H9NH3)2PbBr4 single crystals under high density excitation have been investigated by photoluminescence (PL) spectroscopy. The PL bands associated with the Γ1, Γ2 and Γ5 excitons and the biexcitons have been observed. While the Γ2 exciton and biexciton PL intensities are proportional to the 0.9 and 1.7 power of the excitation density, respectively, the Γ5 exciton PL intensity shows the nonlinear dependence on the excitation density. The excitation‐density dependence of the PL bands is calculated by taking account of the dynamical change of the exciton and biexciton populations in an exciton‐biexciton system consisting of two exciton states and a biexciton state. The calculated results well explain the nonlinear dependence of the Γ5 exciton PL intensity on the excitation density. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Band‐Edge Exciton Fine Structure and Exciton Recombination Dynamics in Single Crystals of Layered Hybrid Perovskites

“…As a consequence of the dielectric and quantum confinement effect, they show strongly bound and stable excitons at room temperature. [19,20] It has been experimentally observed that excitons are tightly confined in the inorganic layers with binding energy as high as a few hundred millielectronvolts (significantly higher than that of 3D perovskites). A comparison of bulk and surface exciton lifetimes yields a room temperature surface recombination velocity of 2 × 10 3 cm s −1 and an intrinsic lifetime of 185 ns.…”

“…Biexciton emission is evidenced at room temperature, with a binding energy of ≈45 meV and a lifetime of 80 ps. [20,23,24] The presence of these quasiparticles is exciting due to their unique role, leading to a better understanding of many body effects and their great promise for photonic applications. Transient photoluminescence resolves the low-lying dark exciton state, with a bright/dark splitting energy estimated to be 10 meV.…”

“…[19,20] It has been experimentally observed that excitons are tightly confined in the inorganic layers with binding energy as high as a few hundred millielectronvolts (significantly higher than that of 3D perovskites). [19,20] It has been experimentally observed that excitons are tightly confined in the inorganic layers with binding energy as high as a few hundred millielectronvolts (significantly higher than that of 3D perovskites).…”

“…[21] This greatly enhanced exciton binding energy makes them particularly interesting for light-emitting applications. [20,23,24] The presence of these quasiparticles is exciting due to their unique role, leading to a better understanding of many body effects and their great promise for photonic applications. [20,23,24] The presence of these quasiparticles is exciting due to their unique role, leading to a better understanding of many body effects and their great promise for photonic applications.…”

“…[18] These advantages make them appealing for future optoelectronic and photonic applications.Unlike their 3D counterparts, the dielectric and quantum confinement of carriers in the 2D perovskite layers gives rise to unusually strong excitonic effects. [19,20] It has been experimentally observed that excitons are tightly confined in the inorganic layers with binding energy as high as a few hundred millielectronvolts (significantly higher than that of 3D perovskites). [21] This greatly enhanced exciton binding energy makes them particularly interesting for light-emitting applications.…”