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Advances in colloidal anisotropic nanocrystals for high-efficiency light-emitting diodes
Colloidal semiconductor nanocrystals have emerged as promising materials for next-generation light-emitting diodes (LEDs) owing to their solution processability, tunable emission wavelengths, narrow emission linewidths, and high photoluminescence quantum yields. Among them, anisotropic nanocrystals, including one-dimensional nanorods (NRs) and two-dimensional nanoplatelets (NPLs), offer additional opportunities for controlling transition dipole moment orientation and light out-coupling efficiency. These unique structural characteristics have enabled significant advances in LED performance beyond those achievable with conventional spherical quantum dots. This review summarizes recent progress in anisotropic semiconductor nanocrystals for light-emitting applications. We first discuss the synthesis and structural modulation of NRs and NPLs, including size and morphology control, heterostructure engineering, and doping strategies. We then review the fundamental operating principles of anisotropic nanocrystal-based LEDs, emphasizing the relationships among nanocrystal structure, carrier dynamics, dipole orientation, and device performance. Recent advances in CdSe-based, perovskite-based, and wide-bandgap semiconductor anisotropic nanocrystal LEDs are highlighted, with particular focuses on heterostructure design, charge-balance regulation, and light-management strategies. In addition, directed assembly approaches for constructing oriented nanocrystal films and their impact on light out-coupling efficiency are discussed. Finally, the remaining challenges are outlined. We believe that continued advances in materials design, device architecture optimization and assembly engineering will further accelerate the development of anisotropic nanocrystal LEDs for high-efficiency next-generation display and solid-state lighting technologies.