“…Several strategies have been developed to prepare high-performance NR-LEDs, including shell coating to enhance the photoluminescence quantum yield (PLQY) of NRs, ligand modification to improve the electrical conductivity of NR films, and device structure optimization to promote charge injection balance and improve the EQE. ,, At present, the record EQE of NR-LEDs is 15.7% and the maximum brightness is ∼104 000 cd/m 2 , which are still lower than those of QLEDs (maximum EQE of 35.6%). ,,,− The EQE of NR-LEDs is limited by several issues, including the lower PLQY of traditional CdSe/CdS NRs compared to that of QDs, the poor film morphology of the emission layer, and imbalanced charge injection in NR-LEDs. ,,, Due to the difficulties in obtaining uniform CdSe NRs, most reports have focused on dot-in-rod NRs. However, we note that the rod-in-rod NRs present a degree of polarization ∼1.5 times higher than that of dot-in-rod NRs, which is crucial for improving the photon out-coupling efficiency of NR-LEDs. , In addition to the PLQY, the aspect ratio of NRs also affects the performance of NR-LEDs by affecting the film morphology of the NR emission layer, ,,,,, since it has been reported that defects or the unevenness of the NR film can lead to leakage current and a low EQE. , In addition, the imbalanced carrier injection caused by the high electron mobility and small electron injection barrier of the widely used ZnO electron transport layer further limits the EQE of NR-LEDs. ,,, Similar to QLEDs, NR-LEDs also face the challenge of efficiency droop, where EQE rapidly decreases with an increase in luminance or current density .…”