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.

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.

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.

Rapid industrialization and unlimited human activities have led to severe environmental challenges, particularly water contamination by persistent organic pollutants, posing serious risks to ecosystems and human health. Photocatalytic technology offers a sustainable remediation for pollutant degradation using solar energy. In this study, we employ ultrathin carbon-encapsulated ZnO nanoparticles, ZnO@C, as an efficient photocatalyst, using methylene blue and methyl orange as model pollutants. The carbon has a favorable band alignment with ZnO for efficient charge transfer. In fact, the optical absorption studies and finite-difference time-domain simulations establish an enhanced absorption and light–matter interaction upon thin uniform carbon encapsulation. Photoluminescence quenching (~80%) indicates reduced electron–hole recombination, facilitated by defect-induced charge transfer from ZnO to carbon. Electron paramagnetic resonance measurements identify superoxide radicals (O₂•⁻) as the dominant reactive species, driving a selective radical-mediated degradation pathway. Compared to pristine ZnO, the ZnO@C system exhibits over 60% higher degradation efficiency. Liquid chromatography–mass spectrometry analyses elucidate the sequential degradation pathway driven by O₂•⁻. The ZnO@C demonstrates excellent photostability and reusability across multiple cycles, with a sixfold increase in kinetic rate constants over pristine ZnO. These improvements highlight the potential of ZnO@C core@shell nanostructures for sustainable environmental remediation