Luminescence From Localized States in Solids: A First‐Principles Perspective

Abstract Localized‐state luminescence (LSL) has emerged as a promising mechanism for high‐performance optoelectronic applications, including lighting, photodetection, and quantum technologies. Characterized by rich and intriguing spectral features, LSL involves significant electron‐phonon coupling, which varies in strength across different systems. First‐principles methods, particularly density functional theory (DFT) and its extensions provide an efficient framework for modeling the LSL process with reasonable accuracy. This comprehensive review examines DFT‐based studies on three representative types of LSL in solids: luminescence from self‐trapped excitons (STEs), normal defects, and intentionally doped ions. The discussion begins with an overview of the entire LSL process, highlighting computational methods for excited state structures and energies, as well as simulations of the luminescent spectrum within a multi‐phonon transition framework. Detailed discussions follow, focusing on the structural distortion modes of STEs, spectral behavior of normal defects, and transition mechanisms in intentionally doped ions. Finally, strategies to address current challenges and advance the theoretical design of high‐performance LSL materials are proposed, offering valuable insights for future developments in the field.