Disentangling the Luminescent Mechanism of Cs₄PbBr₆ Single Crystals from an Ultrafast Dynamics Perspective

Abstract

New all-inorganic perovskites like Cs4PbBr6 provide rich luminescent tools and particularly novel physical insights, including their zero-dimensional structure and controversial emitting mechanism. The ensuing debate over the origin of the luminescence of Cs4PbBr6 inspired us to tackle the issue through fabricating high-quality Cs4PbBr6 single crystals and employing ultrafast dynamics study. Upon photoexcitation, Cs4PbBr6 underwent dynamics steps distinct from that of CsPbBr3, including exciton migration to the defect level on a time scale of several hundred femtoseconds, exciton relaxation within the defect states on the picosecond time scale, and exciton recombination from the subnanosecond to nanosecond time scale. The observation disclosed that crystal defects of Cs4PbBr6 induced green emission while CsPbBr3 mainly relied on quantum confinement to emit at room temperature. The study provides an in-depth understanding of the photoinduced multistep dynamics steps of Cs4PbBr6 associated with display and photovoltaic applications, establishing Cs4PbBr6 as a new candidate for uses associated with the perovskite family of materials.

Low‐Dimensional‐Networked Cesium Lead Halide Perovskites: Properties, Fabrication, and Applications

“…The special 0D Cs 4 PbBr 6 structure adopted a configuration in which Cs minimize the electronic overlap between neighboring octahedra, leading to a localized state confined to individual unit cells. [47][48][49][50][51][52][53] On the other hand, the self-trapped exciton indicated a bound electron-hole pair trapped via strong electron/holelattice coupling, possibly leading to the formation of a polaron in the lattice distortion filed. [34,49,54] The self-trapped exciton has been confirmed in a variety of characterization technologies.…”

“…In the synthesis of single crystals, antisolvent vapor-assisted crystallization is a well-established method. To obtain Cs 4 PbBr 6 crystals, CsBr/PbBr 2 (typically 1:1 [39] or 4:1 [51,53,123] molar ratio) in DMSO were injected into a vial and then stored in a closed glass container under an antisolvent atmosphere (Figure 8a), which was one of either diethyl-ether, dichloromethane or acetone. [39,51,53,81,123] The high vapor pressure of the antisolvent enabled its rapid diffusion into the vial, leading to the formation of crystals.…”

“…To obtain Cs 4 PbBr 6 crystals, CsBr/PbBr 2 (typically 1:1 [ 39 ] or 4:1 [ 51,53,123 ] molar ratio) in DMSO were injected into a vial and then stored in a closed glass container under an antisolvent atmosphere ( Figure a), which was one of either diethyl‐ether, dichloromethane or acetone. [ 39,51,53,81,123 ] The high vapor pressure of the antisolvent enabled its rapid diffusion into the vial, leading to the formation of crystals. After 48–72 h, the as‐formed Cs 4 PbBr 6 single crystals were collected and dried under vacuum.…”

An efficient high-power femtosecond laser based on periodic-layered-Kerr media nonlinear compression and a Yb:YAG regenerative amplifier

“…These results confirmed the potential of periodic-layered-Kerr-media-based technique for the efficient and economical compression of high average power laser amplifiers at high repetition rates. Such source presents a favorable and robust tool for novel manufacturing mechanisms and time-resolved spectroscopy experiments [33][34][35][36].…”

Indication of CsPbBr3 inclusions in zero dimensional Cs4PbBr6 perovskite single crystals by alkylammonium post‐treatment

“…They support their argument by both theoretical calculations and experimental results. [ 2,21–24 ] In a very recent review, Mohammed et al. proposed that there are three different kinds of Cs 4 PbBr 6 ‐based materials, including the non‐emissive‐, defective‐, and hybrid‐Cs 4 PbBr 6 .…”