Bright CsPbI₃ Perovskite Quantum Dot Light-Emitting Diodes with Top-Emitting Structure and a Low Efficiency Roll-Off Realized by Applying Zirconium Acetylacetonate Surface Modification

Zirconium acetylacetonate used as a co-precursor in the synthesis of CsPbI₃ 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 CsPbI₃ QDs with an electroluminescence at 686 nm showed external quantum efficiency (EQE) of 13.7% at a current density of 108 mA cm^-2, which was combined with low efficiency roll-off (maintaining an EQE of 12.5% at a high current density of 500 mA cm^-2) and a high luminance of 14725 cd m^-2, and the stability of the devices being repeatedly lit (cycled on and off at high drive current density) has been greatly enhanced.