Solubility of Dilute SO₂ in Mixtures of <i>N</i>,<i>N</i>‑Dimethylformamide + Polyethylene Glycol 400 and the Density and Viscosity of the Mixtures

In this work, the isothermal gas–liquid equilibrium (GLE) data were measured for the system of polyethylene glycol 400 (PEG 400) + <i>N</i>,<i>N</i>-dimethylformamide (DMF) + SO₂ + N₂ at 308.15 K and 123 kPa with SO₂ partial pressures in the range of (16.8 to 115) Pa. The Henry’s law constant (<i>H</i>′) and standard Gibbs free energy change (Δ<i>G</i>) were calculated from these GLE data. Furthermore, the densities and viscosities of binary mixtures of DMF + PEG 400 were also measured over the whole concentration range at <i>T</i> = (298.15 to 313.15) K. From the experimental data, including density and viscosity values, the excess molar volumes (<i>V</i>_m^E), and viscosity deviations (Δη), the calculated results are fitted to a Redlich–Kister equation to obtain the coefficients and estimate the standard deviations between the experimental and the calculated quantities

Surface Decorating of CH₃NH₃PbBr₃ Nanoparticles with the Chemically Adsorbed Perylenetetracarboxylic Diimide

An organic dye-modified organolead halide CH₃NH₃PbBr₃ nanoparticle (cubic) is prepared successfully by using a perylenetetracarboxylic diimide (PDI) bearing an -NH₃⁺ headgroup as the capping ligand. The nanopartilces are homogeneous with high crystallinity. The photoluminescence of perovskite is quenched completely by the chemically adsorbed PDI molecules. This efficient fluorescence quenching has confirmed that the PDI molecules are anchored on the surface of CH₃NH₃PbBr₃ nanoparticle. The resulting nanoparticles can be dispersed in organic solvents, and the resulting dispersion remains stable for days. This result provides a general guideline for surface engineering of organolead halide CH₃NH₃PbBr₃ nanoparticles

Surface Modification of Methylamine Lead Halide Perovskite with Aliphatic Amine Hydroiodide

By spin-coating method, a thin layer of dodecylamine hydroiodide (DAHI) is introduced to the surface of perovskite CH₃NH₃PbI<i>_x</i>Cl_3–<i>x</i>. This layer of DAHI successfully changes the surface of perovskite from hydrophilic to hydrophobic as revealed by the water contact angle measurement. Significantly enhanced fluorescence intensity and prolonged fluorescence lifetime are found for these modified films in comparison to those of unmodified perovskite films, suggesting that the number of structure defects is reduced dramatically. The compatibility between the perovskite and hole transfer layer (HTL) is also improved, which leads to more efficient hole collection from the perovskite layer by HTL as revealed by the fluorescence spectra, fluorescence decay dynamics, as well as the transient photocurrent measurements. Moreover, the perovskite solar cells (PSCs) fabricated from these modified perovskite films exhibit significantly improved humidity stability as well as promoted photoelectron conversion efficiency (PCE). The result of this research reveals for the first time that the layer of aliphatic amino hydroiodide is a multiple functions layer, which can not only improve the humidity stability but also promote the performance of PSCs by reducing the defect number and improve the compatibility between perovskite and HTL. Because the structure of aliphatic amines can be functionalized with myriad of other groups, this perovskite modification method should be very promising in promoting the performance of PSCs