Underlying Dynamics of Double-Halide Perovskites: Unraveling Structural Complexity, Bandgap Modulation, Optical, and Carrier Dynamics for Next-Generation Optoelectronics

Double-halide perovskites have emerged as promising alternatives to lead-based materials owing to their tunable electronic properties and potential applications in solar cells, light-emitting diodes, and sensors. They allow the incorporation of various metal ions at the B-site, enabling bandgap and carrier mobility adjustments and enhancing their versatility. However, challenges like carrier trapping and structural distortion impede practical use. This review comprehensively analyzes factors like metal-ion arrangement, structural distortions, and the Jahn–Teller effect on emission properties. It discusses the use of the linear combination of atomic orbital theory for predicting band structures, emphasizing equatorial angles in 2D structures for bandgap tuning. It also delves into defect chemistry, examines shallow and deep trap formation, and highlights strategies for improving charge transport, including defect engineering, surface treatments, and compositional adjustments. The integration of various factors and future research directions, such as doping strategies and 2D structures, presented in this work are expected to advance double-halide perovskites in next-generation optoelectronic technologies.