The Journal of Physical Chemistry Letters最新文献

Defect-assisted ion migration is one of the important issues that results in instability and non-radiative losses in hybrid organic–inorganic metal halide perovskite solar cells. In this work, based on the deep potential (DP) model, a long-time-scale molecular dynamics (MD) simulation has been employed to capture the interstitial-assisted iodine migration process. The results indicate that, when interstitial iodine (I_i) begins to migrate, the serious structural distortion becomes mild, weakening the electron–vibration interaction. The deep trap state induced by the iodine trimer undergoes a “deep–shallow–deep” dynamic process, which ultimately leads to an improvement of the carrier lifetime during the interstitial-assisted iodine migration process. Our work confirms that different dynamic processes are strongly correlated in halide perovskites and demonstrates that ion migration, considered to be detrimental, can become benign in a particular case. The reported results provide new fundamental insight to improve the efficiency of CH₃NH₃PbI₃ perovskite solar cells.

This study aims to develop a synthetic protocol for preparing salphen-based hybrid compounds with silsesquioxane T₈ cages anchored at the molecule’s periphery. Three types of coordination compounds featuring κ⁴-N₂O₂-donating atoms were obtained via a sequence of reactions. These compounds differ in the arene linker between the salphen and silsesquioxane fragments. An individual synthetic pathway was developed for the preparation of aldehydes, followed by a tailored strategy for the synthesis of the final complexes employing both solution-based and mechanochemical methods in the solid state. The latter represents a novel technique in silsesquioxane chemistry. The newly designed ligands were used for the coordination of Zn²⁺ ions to evaluate their ligation properties and to determine the photophysical properties of the resulting complexes in comparison to their bare ligand molecules. Using absorption and emission spectroscopy, combined with advanced time-resolved spectroscopic methods, we demonstrated that the photochemical efficiency of these compounds is influenced by their tendency to aggregate in solution, which positively affects their photophysical properties and enhances their potential for photodynamic therapy (PDT). Additionally, we explored the ability of these complexes to generate singlet oxygen (¹O₂) depending on the architecture of the designed ligands. The results indicate that the excited state dynamics plays a crucial role in determining the emission properties of the studied compounds, which may have significant implications for their applications in medicine and materials science.

Hydrogen, crucial for the green energy transition, poses a challenge due to its tendency to degrade surrounding wall materials. To harness hydrogen’s potential, it is essential to identify the parameter(s) of materials that modulates hydrogen–material interaction. In a recent publication, we have shown that the reduction (denitridation) of transition metal (TM) nitrides in hydrogen radicals (H*) stops when their work function drops below a threshold limit. In this work, we tailor the work function of a complex TM oxide by tuning the relative contents of its constituent TM atoms. We show that increasing the fraction of a low-work function TM decreases the work function of the complex oxide, thereby decreasing its reducibility (deoxidation) in H*. This leads to the stabilization of the higher oxidation states of a high-work function TM, which otherwise would be readily reduced in H*. We propose that the work function serves as a tunable parameter, modulating the interaction of hydrogen with TM compounds.