材料科学
纳米棒
二极管
光电子学
发光二极管
纳米技术
作者
Yicheng Zeng,Haibo Liu,Yuan Liu,Weiwei Chen,Fangze Liu,Hongbo Li
标识
DOI:10.1002/adma.202310705
摘要
Abstract The external quantum efficiency (EQE) in light‐emitting diodes (LEDs) based on isotropic quantum dots has approached the theoretical limit of close to 20%. Anisotropic nanorods can break this limit by taking advantage of their directional emission. However, the progress towards higher EQE by using CdSe/CdS nanorods (NRs) faces several challenges, primarily involving the low quantum yield and unbalanced charge injection in devices. Herein, the seeded growth method is modified and anisotropic nanorods are obtained with photoluminescence quantum yield up to 98% by coating a gradient alloyed CdZnSe shell around conventional spherical CdSe seeds. This intermediate alloyed CdZnSe shell combined with a subsequent rod‐shaped CdZnS/ZnS shell can effectively suppress the electron delocalization in the typical CdSe/CdS nanorods due to their small conduction bandgap offset. Additionally, this alloyed shell can reduce the hole‐injection barrier and create a larger barrier for electron injection, both effects promoting a balanced injection of electrons and holes in LEDs. Hence, LEDs are reached with high brightness (160341 cd m −2 ) and high efficiency (EQE = 22%, current efficiency = 23.19 cd A −1 ), which are the highest values to date for nanorod LEDs.
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