Bright CsPbI<sub>3</sub> Perovskite Quantum Dot Light-Emitting Diodes with Top-Emitting Structure and a Low Efficiency Roll-Off Realized by Applying Zirconium Acetylacetonate Surface Modification.

Lu, Min; Guo, Jie; Sun, Siqi; Lu, Po; Wu, Jinlei; Wang, Yu; Kershaw, Stephen V; Yu, William W et al. · Nano Lett · 2020

basic_science · Level V

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Abstract

Zirconium acetylacetonate used as a co-precursor in the synthesis of CsPbI<sub>3</sub> quantum dots (QDs) increased their photoluminescence quantum efficiency to values over 90%. The top-emitting device structure on a Si substrate with high thermal conductivity (to better dissipate Joule heat generated at high current density) was designed to improve the light extraction efficiency making use of a strong microcavity resonance between the bottom and top electrodes. As a result of these improvements, light-emitting diodes (LEDs) utilizing Zr-modified CsPbI<sub>3</sub> QDs with an electroluminescence at 686 nm showed external quantum efficiency (EQE) of 13.7% at a current density of 108 mA cm<sup>-2</sup>, which was combined with low efficiency roll-off (maintaining an EQE of 12.5% at a high current density of 500 mA cm<sup>-2</sup>) and a high luminance of 14 725 cd m<sup>-2</sup>, and the stability of the devices being repeatedly lit (cycled on and off at high drive current density) has been greatly enhanced.