The effect of the loading of nanoparticles on the glass transition temperature, T_g, of polymer nanocomposites is studied by using molecular dynamics simulations. T_g is estimated from the variation of system volume with temperature and the temperature-dependent diffusion of the polymer described by the Vogel–Fulcher–Tammann law. The estimated values of T_g from the two methods are consistent with each other. Results show that T_g can be regulated by changing the volume fraction of nanoparticles, f_NP. A novel shift in T_g is observed, that is, T_g increases with f_NP at f_NP < , while it decreases with increasing f_NP at f_NP > . The basic mechanism behind the novel shift in T_g is the competition between the attraction of nanoparticles towards polymer chains and the fast diffusion of nanoparticles. The increase in T_g at low f_NP is due to the attraction of nanoparticles, whereas the decrease in T_g at high f_NP is attributed to the fast diffusion of nanoparticles. The diffusion of the polymer above T_g is also investigated. The diffusion of the polymer decreases with increasing f_NP below and increases with f_NP above , in agreement with the variation of T_g.

The glass transition temperature (T_g) of polymer nanocomposites is dependent on the size of nanoparticles. The behaviors of the diffusion constant and relaxation time of polymer chains at a temperature above T_g also support the results of T_g.

Perovskite solar cells (PSCs), on account of their ever-increasing power conversion efficiency (PCE), are captivating industrialists. Despite this, the performance of perovskite solar cells, especially the long life span, is the main barrier to PSCs’ commercial deployment where the inefficient perovskite layer is always convicted as the key reason behind it. In reality, the perovskite layer suffers from different intermediate transformations where dimethyl sulfoxide (DMSO), forming PbI₂·DMSO intermediates, plays an essential role in retarding the rapid crystallization of perovskite. Therefore, these intermediate phases govern the morphologies and crystallinities of the final perovskite films. In the comparison of FAPbI₃ and MAPbI₃, which are the two most studied single-cation perovskites, during intermediate phase conversions, the PbI₂·MAI·DMSO adduct provides high-quality perovskite than the PbI₂·FAI·DMSO adduct, which leads to the poor film quality of FA-based single cation and mixed cation perovskites. Herein, the intermolecular exchange of DMSO with FAI in the PbI₂·MAI·DMSO adduct is performed to get MA_xFA_1−xPbI₃ films where the grain size is dramatically enhanced, and a PCE of 20.79% is obtained with superior long term stability.

The impact of polymer chain stiffness characterized by the bending modulus (k_θ) on the glass transition temperature (T_g) of pure polymer systems, as well as polymer nanocomposites (PNCs), is investigated using molecular dynamics simulations. At small k_θ values, the pure polymer system and respective PNCs are in an amorphous state, whereas at large k_θ values, both systems are in a semicrystalline state with a glass transition at low temperature. For the pure polymer system, T_g initially increases with k_θ and does not change obviously at large k_θ. However, the T_g of PNCs shows interesting behaviors with the increasing volume fraction of nanoparticles (f_NP) at different k_θ values. T_g tends to increase with f_NP at small k_θ, whereas it becomes suppressed at large k_θ.