Generalized colloidal synthesis of high-quality, two-dimensional cesium lead halide perovskite nanosheets and their applications in photodetectors

Abstract

All-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) are emerging as an important class of semiconductor materials with superior photophysical properties and wide potential applications in optoelectronic devices. So far, only a few studies have been conducted to control the shape and geometry of CsPbX3 NCs. Here we report a general approach to directly synthesize two-dimensional (2D) CsPbX3 perovskite and mixed perovskite nanosheets with uniform and ultrathin thicknesses down to a few monolayers. The key to the high-yield synthesis of perovskite nanosheets is the development of a new Cs-oleate precursor. The as-synthesized CsPbX3 nanosheets exhibit bright photoluminescence with broad wavelength tunability by composition modulation. The excellent optoelectronic properties of CsPbX3 nanosheets combined with their unique 2D geometry and large lateral dimensions make them ideal building blocks for building functional devices. To demonstrate their potential applications in optoelectronics, photodetectors based on CsPbBr3 nanosheets are fabricated, which exhibit high on/off ratios with a fast response time.

All-Inorganic Perovskite CsPb2Br5 Microsheets for Photodetector Application

“…As one kind of the perovskites nanomaterials, all-inorganic lead halide perovskites CsPbX 3 (X = I, Br, Cl) are generally recognized as one probable substitute of organic perovskites [15,16]. To date, all-inorganic cesium lead halide perovskite have generated considerable attention because of their higher stability and outstanding optoelectronic properties comparable to the hybrid organic-inorganic perovskites [17][18][19][20].…”

Graphene, Transition Metal Dichalcogenides, and Perovskite Photodetectors

“…This work demonstrates that all-inorganic perovskite CsPbBr 3 NSs have a great potential in photodetector application. Next, Lv et al reported a similar result on CsPbBr 3 NSs photodetectors [56]. Then, our group reported that the responsivity could be improved by the annealing, which was demonstrated to increase coupling energy but decrease exciton binding energy resulting from ligand rearrangement.…”

Two-Dimensional Halide Perovskites for Emerging New- Generation Photodetectors

“…Under illumination of a laser diode at 450 nm, a significant increase in photocurrents was observed. Besides, excellent optical switching and stability of this photodetector were also proved under 1 Hz pulse laser (450 nm) at a fixed light density of 13 mW cm −2 with a bias voltage of 1 V. Through fitting the photocurrent response curve (Figure 7e), the rise time was estimated to be 17.8 ms and the decay times were determined to be 14.7 and 15.2 ms [78]. Li et al used a combined solutionprocessed and vapor-phase conversion method for the synthesis of 2D CH 3 NH 3 PbI 3 nanosheets with a thickness of ~20 nm [79].…”

“…Cyan-emitting CsPbBr 3 nanosheets based photodetector was reported by Lv et al [78]. The source-drain current of CsPbBr 3 nanosheet film in the dark was detected to be on the order of 10 −12 A due to the existence of long-chain organic ligands on the nanosheet surface.…”

“…(e) Time-resolved PL decay transient spectra for CsPbBr 3 nanosheet thin films [76]. (f) Optical microscopic image of the device structure for the CH 3 NH 3 PbI 3 vertical-type photodetector [78]. (g) The band alignment for the ITO/perovskite/Au vertical heterostructure [79].…”