Differences and regulation of self-trapped luminescence in one-dimensional Pb-based and Sn-based perovskites

One-dimensional (1D) perovskites have garnered significant interest due to their structural stability and self-trapped emission, with Sn-based and Pb-based perovskites being the primary focus. However, the reasons underlying the similarities and differences in the luminescent properties of these two types of perovskites remain unexplored in a systematic manner. Moreover, their properties can be influenced by external factors such as humidity, temperature, and illumination, which may induce subtle lattice expansions or contractions. In this study, we employ density functional theory (DFT) calculations to systematically investigate the similarities and differences in the optical properties and structural stability of 1D perovskites (C₄N₂H₁₄)PbBr₄ and (C₄N₂H₁₄)SnBr₄, as well as the effects of strain on these materials. Our results reveal that the molecular dissociation energy is higher for Pb-based perovskites than for their Sn-based counterparts, and both systems show increasing dissociation energies under greater lattice size. Under strain conditions, both the absorption and emission energies show a regular variation. This trend is more pronounced in Sn-based perovskites, whose optical characteristics are more sensitive to strain, indicating a higher degree of tunability. This enhanced sensitivity is attributed to the more active lone-pair electrons in Sn-based perovskites, inducing stronger lattice distortions and electron-phonon coupling. Furthermore, strain engineering can effectively modify the carrier mobility, optical absorption, and transition dipole moment of 1D perovskite materials, enabling improvements in both phosphor-based luminescence and electroluminescent applications.