Hybrid halide perovskites
represent one of the most promising solutions
toward the fabrication of all solid nanostructured solar cells, with
improved efficiency and long-term stability. This article aims at
investigating the structural properties of iodide/chloride mixed-halide
perovskites and correlating them with their photovoltaic performances.
We found out that, independent of the components ratio in the precursor
solution, Cl incorporation
in an iodide-based structure, is possible only at relatively low concentration
levels (below 3–4%). However, even if the material band gap
remains substantially unchanged, the Cl doping dramatically improves
the charge transport within the perovskite layer, explaining the outstanding
performances of meso-superstructured solar cells based on this material.
We report here on a detailed study on PbS colloidal quantum dots. A characterization via X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) allowed us to reliably determine the diameter and the shape of the nanocrystals. These data, together with second-derivative analysis of the absorption spectra, allowed us to determine the size dependence of seven transitions in the absorption spectrum; some of these transitions were identified on the basis of their normalized confinement energy. The size dependence of the first excitonic transition was best modeled by a four-band envelope approach which considers the anisotropy of the band edges (Andreev, A. D.; Lipovskii, A. A. Phys. Rev. B: Condens. Matter Mater. Phys. 1999, 59, 15402-15404). The extinction coefficients were calculated using concentrations obtained from inductively coupled plasma atomic emission spectrometry (ICP-AES), and their size dependence was found to follow a power law with exponent equal to approximately 2.5. In contrast with what was expected from the effective mass approximation, the per particle absorption cross section of the lowest transition was found to be strongly dependent on the particle size.
Hybrid halide perovskites represent one of the most promising solutions toward the fabrication of all solid nanostructured solar cells with improved efficiency and long-term stability. This article aims at investigating the structural properties of the iodide/chloride mixed-halide perovskites and correlating them with the photovoltaic performances of the related sensitized solar cells. We found out that, independently on the components ratio in the precursor solution, Cl incorporation, in a I-based structure, is possible only at relatively low concentration levels (below 3-4%). However, even if the material band-gap remains substantially unchanged, incorporation of Cl as a dopant dramatically improves the charge transport within the perovskite layer, explaining the outstanding performances of meso-superstructured solar cells based on this material.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.