Exploring the influence of iron doping on structural, morphological and optical properties of chemical bath deposited cadmium selenide thin films for optoelectronic applications.

This research investigates the structural, morphological, and optical properties of Cadmium Selenide (CdSe) thin films deposited via the Chemical Bath Deposition (CBD) Technique, focusing on the impact of Iron (Fe) doping. Using Cadmium Chloride (CdCl2) and Ferrous chloride (FeCl2) as precursor materials, the research investigates how Fe doping affects the structural and photoelectric characteristics of the films. Employing various characterization methods including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and UV-Vis NIR spectroscopy, the study provides a comprehensive analysis of the films. XRD analysis confirms the formation of a cubic structure with a predominant orientation along the (111) plane, consistent with XRD peaks. Additionally, XRD data reveals the degradation of thin films post-annealing. Crystalline size and strain are determined using the Debye-Scherrer and Wilson formulae, while lattice constant and Size-strain plots are derived from X-ray line broadening. The average crystallite size ranges from 12 to 21 nm. Optical band gaps are found to be 2.25 eV, 2.91 eV, 2.87 eV, and 2.85 eV for the samples. Interestingly, a decrease in crystal size with increasing doping concentration correlates with a reduction in bandgap. This investigation offers valuable insights into the fabrication and characterization of CdSe thin films, particularly highlighting the impact of Fe doping on their structural and optical properties. Overall, this study provides valuable insights into the fabrication and characterization of CdSe thin films, emphasizing the importance of precise doping control for tailoring material properties and advancing their applications in photovoltaic and optoelectronic devices.

Accelerated Li Penetration and Crack Propagation Due to Mechanical Degradation of Sulfide-Based Solid Electrolyte.

This work presents quantitative investigations into the relationships between lithium dendrite growth in the defects of Li6PS5Cl (LPSCl) solid electrolyte (SE), crack nucleation and propagation in the SE, and the associated mechanical forces driving these dendrites and cracks. Two different growth modes for lithium dendrites are identified by ex situ scanning electron microscopy (SEM) observation: longitudinal cracking inside pores in the SE and lateral penetration along boundaries of the SE particles. These in situ TEM tests reveal that concentrated Li plating in a nano-sized defect on the LPSCl surface will lead to the nucleation and propagation of cracks into the LPSCl under a stress much smaller than the expected mechanical strength of the LPSCl material. This unexpected mechanical degradation is caused by a reduction in the mechanical strength of LPSCl during electrochemical charge/discharge cycling, resulting from a disorder in the crystal structure of LPSCl as revealed by DFT simulations. Due to this mechanical degradation of LPSCl, the threshold force necessary to initiate crack growth is much lower than the previously expected force to drive dendrite growth.