Small-molecule non-fullerene acceptors (SM-NFAs) featuring a three-dimensional and four-bladed propeller-like structure have gained attention due to their unique molecular framework as guest component in ternary organic solar cells (TOSCs). However, there is currently a scarcity of theoretical research into the photovoltaic properties of these SM-NFAs. This gap is especially pronounced when it comes to comprehending how modifications to their end groups (EGs) influence their electronic structures. In this work, SF-BTA1, SF-BTA2, and SF-BTA3 SM-NFA are selected since they have been experimentally synthesized and have different impacts on the performance of TOSCs. Using density functional theory (DFT) and time-dependent DFT (TDDFT), we have computed and analyzed their ground state and excited state properties, including molecular planarity, electrostatic potential maps and their corresponding fluctuations, dipole moments, frontier molecular orbitals, electron-hole distributions, UV-Vis absorption spectra, singlet-triplet energy gap difference (∆E ST), and exciton binding energy, as well as the open-circuit voltage of OSCs based on these four-bladed propeller-like molecules. The theoretical results align well with experimental data. Furthermore, as a guest acceptor, SF-BTA1 exhibits the smallest electrostatic potential fluctuations and singlet-triplet energy gap (∆E ST). This implies that these two factors could play crucial roles in evaluating whether a four-bladed propeller-like molecule is suitable to serve as an effective guest acceptor. Our results not only unveil the underlying mechanism about the roles of these NFAs in TOSCs but also provide valuable insights for the further design and optimization of highly efficient TOSCs.

Dialkyl peroxides may decompose under heating and illumination conditions, and consequently cause an explosion or fire possibility. However, they can promote diesel-degraded branching reaction, enhance diesel spontaneous combustion ability, and accelerate the chain reaction of fuel combustion. In this study, one series of dialkyl peroxides, i.e. methyl, ethyl, isopropyl, and di-t-butyl peroxide, which have different numbers of terminal methyl groups, have been modeled. We have systematically explored their stabilities under heating and illumination conditions by using CCSD(T), DFT/TDDFT, and variational transition state theory. We focus on the rate constants of thermal dissociation of peroxide bonds and absorption spectra because previous experimental and calculated thermal kinetic parameters are not consistent and the absorption spectra of these compounds are few. Based on the calculated data including rate constants and simulated absorption spectra, we find out that di-t-butyl peroxide is the best candidate among four compounds considering the stability under both heat and light. The most striking finding is that the previous assumption that the activation energy of O-O decomposition equals O-O bond energy may be wrong.