Spectra stable blue perovskite light-emitting diodes

Abstract

Device performance and in particular device stability for blue perovskite light-emitting diodes (PeLEDs) remain considerable challenges for the whole community. In this manuscript, we conceive an approach by tuning the ‘A-site’ cation composition of perovskites to develop blue-emitters. We herein report a Rubidium-Cesium alloyed, quasi-two-dimensional perovskite and demonstrate its great potential for pure-blue PeLED applications. Composition engineering and in-situ passivation are conducted to further improve the material’s emission property and stabilities. Consequently, we get a prominent film photoluminescence quantum yield of around 82% under low excitation density. Encouraged by these findings, we finally achieve a spectra-stable blue PeLED with the peak external quantum efficiency of 1.35% and a half-lifetime of 14.5 min, representing the most efficient and stable pure-blue PeLEDs reported so far. The strategy is also demonstrated to be able to generate efficient perovskite blue emitters and PeLEDs in the whole blue spectral region (from 454 to 492 nm).

Low‐dimensional metal halide perovskites and related optoelectronic applications

“…Liang et al improved the crystal quality by converting poly‐crystalline PEA 2 PbBr 4 thin films into single‐crystalline micro‐sized nanoplates via solvent vapor annealing and showed efficient room‐temperature violet EL at 410 nm (Figure A) . Compared to the pure phase RP perovskite components (one value of n only), poly‐crystalline RP perovskite films containing multiple phases (multiple values of n) have superior light‐emission performance . Yuan et al and Huang et al independently reported LEDs incorporated with mixed layered perovskite materials, displaying impressive performance and stability.…”

“…The mixed compounds act like a photocarrier concentrator, funneling the charge carriers from high‐bandgap materials to the lowest‐bandgap ones and boosting the external quantum efficiency (EQE) to 8.8% and 11.7% (Figure B‐C), respectively . Jiang et al tuned the “A‐site” cation by using a Rubidium‐Cesium alloyed perovskite, demonstrating a spectra‐stable blue LED with a peak EQE of 1.35% (Figure D) . In addition to the composition engineering, other strategies like surface passivation, crystallite tailoring, structure engineering, and so forth were also applied for performance and longevity improvement .…”

“…D, EQE values of 2D RP perovskite‐based LEDs vs current density. Reproduced with permission . Copyright 2019 Nature Publishing Group.…”

“…134,135 Jiang et al tuned the "A-site" cation by using a Rubidium-Cesium alloyed perovskite, demonstrating a spectra-stable blue LED with a peak EQE of 1.35% ( Figure 6D). 136 In addition to the composition engineering, other strategies like surface passivation, crystallite tailoring, structure engineering, and so forth were also applied for performance and longevity improvement. [137][138][139][140][141] Yang et al utilized trioctylphosphine oxide treatment to passivate the surface of quasi-2D PEA 2 (FAPbBr 3 ) n-1 PbBr 4 films, achieving an EQE of 14.36%.…”

“…Reproduced with permission. 136 Copyright 2019 Nature Publishing Group. E, View of the unit cell of Na 2 Cs n−1 Pb n Br 3n+1 perovskites with different values of hni (1 and 2).…”