One-Pot Synthesis and Structural Evolution of Colloidal Cesium Lead Halide–Lead Sulfide Heterostructure Nanocrystals for Optoelectronic Applications

Abstract

Heterostructures, combining perovskite nanocrystals (PNC) and chalcogenide quantum dots, could pave a path to optoelectronic device applications by enabling absorption in the near-infrared region, tailorable electronic properties, and stable crystal structures. Ideally, the heterostructure host material requires a similar lattice constant as the guest which is also constrained by the synthesis protocol and materials selectivity. Herein, we present an efficient one-pot hot-injection method to synthesize colloidal all-inorganic cesium lead halide−lead sulfide (CsPbX 3 (X = Cl, Br, I)−PbS) heterostructure nanocrystals (HNCs) via the epitaxial growth of the perovskite onto the presynthesized PbS nanocrystals (NCs). Optical and structural characterization evidenced the formation of heterostructures. The embedding of PbS NCs into CsPbX 3 perovskite allows the tuning of the absorption and emission from 400 to 1100 nm by tuning the size and composition of perovskite HNCs. The CsPbI 3 −PbS HNCs show enhanced stability in ambient conditions. The stability, tunable optical properties, and variable band alignments accessible in this system would have implications in the design of novel optoelectronic applications such as light-emitting diodes, photodetectors, photocatalysis, and photovoltaics.

Defect Passivation Results in the Stability of Cesium Lead Halide Perovskite Nanocrystals

“…After the injection of the Cs precursor, PbSe NPs are consumed during the formation of CsPbBr 3 that grows epitaxially over the surface of PbSe. The epitaxial growth occurs due to the resemblance of the perovskite cubic crystal structure with the PbSe structure . In this process, the outermost Pb layer of CsPbBr 3 acts as the interface between CsPbBr 3 and PbSe.…”

“…In recent times, designing heterostructures with suitable counterparts has been considered as an effective approach to passivate the surface defects and enhance the stability of LHPs. − A few recent reports indicate the possibility of heterostructure formation of LHPs with lead chalcogenides because of their same cubic crystal structures with low lattice mismatch. , Lead chalcogenide NCs also act as the protecting layer of LHPs from humidity because of their hydrophobic nature, which enhances the stability of LHPs in an ambient environment. − More recently, Rogach et al reported a facile strategy to design CsPbI 3 /PbSe nanoheterostructures (NHSs) using trioctyl phosphine (TOP)–selenium (Se) powder as the source of Se precursor . Furthermore, the Nripan and Zhang group synthesized heterostructures of CsPbX 3 (X: Cl, Br, I) with PbS using thioacetamide as the sulfur precursor. , These studies discuss the passivation of surface defects, tuning their electronic properties and enhancing the stability of perovskites. However, to the best of our knowledge, the effect of the size of lead chalcogenide on its optoelectronic properties is yet to be explored.…”

“…28 Furthermore, the Nripan and Zhang group synthesized heterostructures of CsPbX 3 (X: Cl, Br, I) with PbS using thioacetamide as the sulfur precursor. 29,30 These studies discuss the passivation of surface defects, tuning their electronic properties and enhancing the stability of perovskites. However, to the best of our knowledge, the effect of the size of lead chalcogenide on its optoelectronic properties is yet to be explored.…”

Progress in the preparation and application of CsPbX3 perovskites

“…49 Tong et al improved the hot injection method, such as adding zeolite-encapsulated CsPbX 3 NCs, doping with Mn + , and in situ growth of CsPbX 3 NCs in metal-organic framework crystals, which improved the luminescence efficiency of the materials. 7,17,28,50–57 Zhang et al prepared dense and uniform CsPbX 3 thin films by thermal evaporation and applied them in lasers, LEDs, PSCs, and other photoelectric fields. 1,16,35,58–64 In recent years, electrospinning has emerged as a new method to prepare CsPbX 3 .…”

Upconversion Luminescence via Anion Exchange in Perovskite Quantum Dots for Anticounterfeiting Inkjet Printing

“…In the past decade, cesium lead halide (CPX 3 , X = Cl, Br, and I) perovskite quantum dots (PeQDs) have attracted a lot of attention due to the outstanding optical properties such as the large absorption coefficient, high quantum yields, emission peaks with narrow full width at half maximum (FWHM), and so on. , In addition, the ease of tuning the band gap via modulating the halide composition, thus shifting the single-peak emissive profiles from deep blue to red continuously, endows the materials with huge potential in wide applications such as displays, photovoltaics, optoelectronics, and so on. − Meanwhile, lanthanide-doped upconversion nanoparticles (UCNPs), giving off anti-Stokes upconversion luminescence (UCL) under 980 nm NIR laser excitation, have demonstrated unparallel virtues against Stokes luminescence in various fields. − However, unlike PeQDs, UCNPs critically rely on the dopants’ energy levels, with fixed UCL emissive peaks at certain wavelengths. Consequently, the UCL manipulation strategy has always been intensively focused over the decades.…”