This paper reports the synthesis of silver nanoparticles coated with porous silica (Ag@Silica NPs) using an assisted laser ablation method. This method is a chemical synthesis where one of the reagents (the reducer agent) is introduced in nanometer form by laser ablation of a solid target submerged in an aqueous solution. In a first step, a silicon wafer immersed in water solution was laser ablated for several minutes. Subsequently, an AgNO3 aliquot was added to the aqueous solution. The redox reaction between the silver ions and ablation products leads to a colloidal suspension of core-shell Ag@Silica NPs. The influence of the laser pulse energy, laser wavelength, ablation time, and Ag+ concentration on the size and optical properties of the Ag@Silica NPs was investigated. Furthermore, the colloidal suspensions were studied by UV–VIS-NIR spectroscopy, X-Ray diffraction, and high-resolution transmission electron microscopy (HRTEM).

In this work, a review focused on the recent development of antimony sulfide selenide (Sb₂(S,Se)₃) solar cells is presented. In particular, experimental and theoretical results are discussed to understand the current limiting factors of this technology, as well as possible routes for device promotion. The Sb₂(S,Se)₃ compound is introduced as an attractive compound for single junction and multijunction solar cells since it is described by a band-gap that can be tailored in the range of 1.1–1.8 eV. Furthermore, improved transport properties are observed in solar cells when SnO₂:F is used as substrate due to better ribbons orientation. In addition, defect energy levels in the range of 0.49–0.52 eV and 0.69–0.81 eV associated to V_Sb and Se_Sb (or S_Sb), respectively result in carrier lifetime values in the range of 0.1–67 ns. It is demonstrated that, unlike other semiconductor compounds, temperatures lower than 450 °C are required for Sb₂(S,Se)₃ processing. Moreover, the highest solar cell efficiency of 10.7% has been reported by the hydrothermal method. Although Sb₂(S,Se)₃ is a stable compound, it is found that there are some instability problems concerning solar cells due to the use of the Spiro-OMeTAD as the hole transport layer. Finally, theoretical results show that interface defects are the main reason for low experimental efficiencies. In particular, losses at the CdS/Sb₂(S,Se)₃ interface are introduced as dominant. In this sense, the introduction of Zn to the CdS compound is presented as a potential solution, which can result in higher solar cell efficiencies along with the reduction of Cd concentration.

The synthesis processes of metallic nanoparticles have seen a growing interest in recent years, mainly by the potential applications of the phenomenon of localized surface plasmon resonance associated with metallic nanoparticles. This paper shows a fast method to synthesize silver, gold and silver/gold alloy nanoparticles coated with a porous silica shell by the assisted laser ablation method in three steps. The method involves a redox chemical reaction where the reducing agent is supplied in nanometric form by laser ablation. In the first step, a silicon target immersed in water is ablated for several minutes. Later, AgNO₃ and HAuCl₄ aliquots are added to the solution. The redox reaction between the silver and gold ions and products resulting from ablation process can produce silver, gold or silver/gold alloy nanoparticles coated with a porous silica shell. The influence of the laser pulse energy, ablation time, Ag⁺ and Au³⁺ concentration, as well as the Ag⁺/Au³⁺ ratio, on optical and structural properties of the nanostructures was investigated. This work represents a step forward in the study of reaction mechanisms that take place during the synthesis of nanoscale materials by the assisted laser ablation technique.

Cu2ZnSnS4 (CZTS) thin films processed by spray pyrolysis technique have attracted a great deal of attention from scientific community for solar cell applications. It is well known that Cu-poor and Zn-rich conditions are required for a good solar cell performance regardless of the method used for CZTS thin film deposition. However, few reports are found along the literature to explain such results. In this work, a comparison on the physical properties of CZTS thin films processed under stoichiometric (Cu2ZnSnS4) and optimal (Cu1.6Zn1.1Sn0.9S4) compositional ratios by spray pyrolysis method is presented. The impact of different substrate temperatures on structural, morphological, optical and electrical properties considering both compositional conditions is studied. For this purpose, characterization techniques such as XRD, Raman, XRF, EDX, AFM, transmittance and reflectance measurements, I-V, I-T and Hall measurements were performed. It is demonstrated that samples deposited under optimal compositional ratios present better structural and morphological properties as well as lower contribution of secondary phases along with band-gap energy values near to 1.5 eV as required for solar cell applications. From the electrical point of view, higher resistivity and grain boundary barrier height values along with a lower density of defects at grain boundary are reported for CZTS deposited under optimal compositional ratios. In this sense, this work helps to clarify why stoichiometric condition in CZTS samples produces lower solar cell performances.