In this work a colloidal approach to synthesize water-soluble CdSe quantum dots (QDs) bearing a surface ligand, such as thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA), glutathione (GSH), or thioglycerol (TGH) was applied. The synthesized material was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy (UV-Vis), and fluorescence spectroscopy (PL). Additionally, a comparative study of the optical properties of different CdSe QDs was performed, demonstrating how the surface ligand affected crystal growth. The particles sizes were calculated from a polynomial function that correlates the particle size with the maximum fluorescence position. Curve resolution methods (EFA and MCR-ALS) were employed to decompose a series of fluorescence spectra to investigate the CdSe QDs size distribution and determine the number of fraction with different particle size. The results for the MPA-capped CdSe sample showed only two main fraction with different particle sizes with maximum emission at 642 and 686 nm. The calculated diameters from these maximum emission were, respectively, 2.74 and 3.05 nm.

Lead (Pb) halide perovskite nanocrystals, with the general formula APbX3, where A=CH3NH3+, CH(NH2)2+, or Cs+ and X=Cl−, Br−, or I−, have emerged as a class of materials with promising properties due to their remarkable optical properties and solar cell performance. However, important issues still need to be addressed to enable practical applications of these materials, such as instability, mass production, and Pb toxicity. Recent studies have carried out the replacement of Pb by various less‐toxic cations as Sn, Ge, Sb, and Bi. This variety of chemical compositions provide Pb‐free perovskite and metal halide nanostructures with a wide spectral range, in addition to being considered less toxic, therefore having greater practical applicability. Highlighting the necessity to address and solve the toxicity problems related to Pb‐containing perovskite, this review considers the prospects of the Pb‐free perovskite, involving synthesis methods, and properties of them, including advantages, disadvantages, and applications.

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Perovskite‐based solar cells (PSCs) are some of the most promising devices for capturing photovoltaic energy. Efficiency has increased from single digits to a certified 25.7%, an unprecedented improvement for any solar cell technology. Incorporating carbon materials into perovskite solar cells promises to be revolutionary in the solar cell field by increasing stability, decreasing manufacturing costs, and making them attractive for commercialization. Here, an overview of the advances in carbon‐based perovskite solar cells (C–PSCs) that incorporate different carbon materials as back contact on different device architectures is presented. An overview of PSC architectures and high‐ and low‐temperature C–PSCs is provided. Additionally, recent advances in the main carbon materials applied in the field, such as graphene, carbon nanotubes, carbon dots, and biocarbon, are presented. Finally, a summary of carbon materials applied to C–PSCs is provided.