Excess Ion-Induced Efficiency Roll-Off in High-Efficiency Perovskite Light-Emitting Diodes.

ACS Applied Materials & Interfaces
Yongheng JiaNi Zhao

Abstract

Applying extensively excess ammonium halides in forming perovskites is a widely used approach to achieve high-performance perovskite light-emitting diodes (PeLEDs). However, most of these PeLEDs suffer from severe external quantum efficiency (EQE) roll-off at high current densities, thereby restricting the realization of high-brightness PeLEDs and laser diodes. In this work, we explore the underlying mechanism of the EQE roll-off in high-efficiency formamidinium lead iodide (FAPbI3)-based PeLEDs. By combining voltage-dependent electrical stress measurements and ex situ ion distribution analysis of PeLEDs, we found that the electric field-driven migration and local segregation of excess iodide ions, originated from nonstoichiometric precursors, trigger the EQE roll-off via promoting imbalanced charge injection. Based on this discovery, we introduced a simple wash-off treatment with chloroform to remove the excess iodides from the perovskite surface and demonstrated that the treatment is highly effective in suppressing the roll-off behavior. By combining the treatment and the use of an ultrathin poly(methyl methacrylate) (PMMA) interlayer, we achieved a high-brightness PeLED with an EQEmax of 19.6%, a critical current density of ...Continue Reading

References

Nov 26, 2014·Advanced Materials·Young-Hoon KimTae-Woo Lee
Jun 28, 2016·Nature Nanotechnology·Mingjian YuanEdward H Sargent
Aug 31, 2018·Advanced Materials·Li Na QuanEdward H Sargent
Nov 22, 2018·Nature Communications·Hoyeon KimNoel C Giebink
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Jun 24, 2020·ACS Applied Materials & Interfaces·Tai ChengChihaya Adachi
Apr 30, 2021·Journal of the American Chemical Society·Shaun TanYang Yang
May 23, 2021·Light, Science & Applications·Yanfeng MiaoJianpu Wang

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