Jonathan Prilusky

CsPbBr₃ (CPB) perovskite nanocrystals (NCs) have attracted considerable interest due to their outstanding charge carrier mobility, long diffusion lengths, and efficient visible light absorption, making them ideal candidates for photocatalysis, light-emitting diodes (LEDs), solar cells, and photodetectors. However, their practical applications are limited by poor environmental stability. We employed a metal-organic framework (MOF) to address this challenge as a stabilizing matrix, selecting ZIF-8 for its exceptional thermal and chemical stability, high surface area, and versatile synthesis routes. The CPB/ZIF-8 nanocomposite was synthesized by integrating hot-injection-produced CPB nanocrystals with ZIF-8 using an optimized mixing approach, ensuring a uniform NCs distribution. Electron microscopy (EM) analysis confirmed the well-controlled and uniform distribution of the NCs on the surface of the ZIF-8. Moreover, the Fourier-transform infrared spectroscopy (FTIR) revealed ligand exchange, where the imidazole linkers of the ZIF-8 structure replace the NCs ligands. The process promotes almost epitaxial attachment of the latter, thus promoting effective charge interactions in the integration process. The unshifted absorbance spectra verified the preservation of optical activity, whereas a 92% quenching in photoluminescence (PL) indicated efficient charge separation and reduced electron-hole recombination. To investigate charge transfer mechanisms, photocatalytic dye degradation under visible light irradiation was employed using methyl orange (MO) and bromocresol green (BCG) as model dyes. The CPB/ZIF-8 nanocomposite exhibited significantly enhanced photocatalytic performance, achieving 1.48 and 1.75 times higher degradation rates for MO and BCG, respectively, compared to pristine CPB NCs. Electron paramagnetic resonance (EPR) studies demonstrated superior radical generation capabilities, particularly hydroxyl radicals (•OH), further confirming enhanced charge transfer and photocatalytic efficiency. These findings underscore the synergistic interaction between CPB NCs and ZIF-8, positioning the CPB/ZIF-8 nanocomposite as a promising material for photocatalysis and optoelectronic applications.

Zero-dimensional (0D) and three-dimensional (3D) halide perovskite nanocrystals (HP-NCs), owing to their unique optoelectronic properties, are extensively studied for photocatalytic activity. However, HPs are highly sensitive to light, humidity, and other environmental factors, which accelerate their decomposition. Understanding the decomposition process is crucial for gaining insights into how to stabilize HP-NCs. Here, we investigate the radical-driven decomposition process and dynamics of the 0D C4PbBr6 and 3D CsPbBr3 NCs under the influence of visible light and a polar solvent by electron paramagnetic resonance (EPR) spectroscopy. Our findings indicate that light accelerates radical formation over time, making the decomposition of HP-NCs a self-sustaining process. Upon illumination of the NCs, hydroperoxyl radicals are formed first, followed by unconventional Br, Cs, and Pb-related radicals, indicating the initiation of NC decomposition. The decomposition of CsPbBr¬3 NCs starts after 3 min of light exposure, while C4PbBr6 NCs take 18 min, indicating the greater stability of the latter. Additionally, we evaluated the photocatalytic activity of the HPs toward degrading organic dyes. The 3D CsPbBr3 NCs performed as superior photocatalysts compared to their 0D Cs4PbBr6 NCs counterparts. Yet, linking the results of EPR measurements with the photocatalytic efficacy suggests that the CsPbBr3 NCs undergo degradation during the photocatalytic process, thereby serving as a sacrificial agent to enhance photocatalytic activity. The understanding derived from EPR spectroscopy in tracking radical formation and dynamics can be extended to enhance the stability and efficiency of various nanomaterials in optoelectronic and photocatalytic applications, thus contributing to advancements beyond the HP family.

Halide perovskite nanowires (HP-NWs) exhibit fascinating optical properties, making them attractive for advanced technologies. However, instability and lack of an effective synthetic protocol limit their commercialization. To address this, we use nanoporous anodized aluminum oxide (AAO) metamaterial as templates for the growth of perovskite (CsPbBr3) NW arrays. AAO functions as both growth template and stabilizing medium. The NW array exhibits strong light-trapping ability, the pore geometric features (pore radius-R and distance between pores-d) have the potential to enhance the light-matter interactions (LMI). We demonstrate the impact of R and d on LMI within the AAO/CsPbBr3 system using theoretical Finite Difference Time Domain (FDTD) simulations for the first time. Optimal LMI was observed with R=d=25 nm and R=d=50 nm. We report ligand-free synthesis of CsPbBr3 NW arrays via spin-coating, drop-casting, and inverse temperature crystallization (ITC). The spin-coating and drop-casting yielded poor pore filling while the modified ITC method yielded nearly complete (>90%) pore filling with significant NW lengths. Our findings highlight the potential of AAO templates for protecting CsPbBr3 and addressing synthetic challenges in HPs and other semiconductor NW arrays. This study provides valuable references for LMI in HPs and advances HPs and NW array-based optical devices and renewable energy applications

Halide perovskites (HPs) have gained significant interest in the scientific and technological sectors due to their unique optical, catalytic, and electrical characteristics. However, the HPs are prone to decomposition when exposed to air, oxygen, or heat. The instability of HP materials limits their commercialization, prompting significant efforts to address and overcome these limitations. Meanwhile, the transition metal dichalcogenides, such as MoS2, are chemically stable and offer versatile properties suitable for electronic, optical, and catalytic applications. The layered structure of MoS2 allows for the development of protective coatings for other nanoparticles. In this study, we successfully synthesized a novel CsPbBr3@MoS2 core-shell nanostructure (CS-NS) by enveloping CsPbBr3 within a MoS2 shell for the first time. We also demonstrate a significant enhancement in the stability of CS-NSs when dispersed in polar solvents for extended periods. Remarkably, the hybrid CS-NSs exhibits an absorption spectrum closely aligned with MoS2 and photoluminescence (PL) quenching, indicating the potential for charge or energy transfer. We used finite difference time domain (FDTD) simulations to evaluate the efficiency of CS-NS-based solar cells and their potential for performance enhancement. This groundbreaking CS-NSs represents a significant advancement in harnessing halide perovskite materials for applications in photovoltaics and various optoelectronic devices.

Halide perovskites-based solar cells are drawing significant attention due to their high efficiency, versatility, and affordable processing. Hence, halide perovskite solar cells have great potential to be commercialized. However, the halide perovskites (HPs) are not stable in an ambient environment. Thus, the instability of the perovskite is an essential issue that needs to be addressed to allow its rapid commercialization. In this work, WS₂ nanoparticles (NPs) are successfully implemented on methylammonium lead iodide (MAPbI₃) based halide perovskite solar cells. The main role of the WS₂ NPs in the halide perovskite solar cells is as stabilizing agent. Here the WS₂ NPs act as heat dissipater and charge transfer channels, thus allowing an effective charge separation. The electron extraction by the WS₂ NPs from the adjacent MAPbI₃ is efficient and results in a higher current density. In addition, the structural analysis of the MAPbI₃ films indicates that the WS₂ NPs act as nucleation sites, thus promoting the formation of larger grains of MAPbI₃. Remarkably, the absorption and shelf life of the MAPbI₃ layers have increased by 1.7 and 4.5-fold, respectively. Our results demonstrate a significant improvement in stability and solar cell characteristics. This paves the way for the long-term stabilization of HPs solar cells by the implementation of WS₂ NPs.