Enhancing the Performance of Quasi-2D Perovskite Light-Emitting Diodes Using Natural Cyclic Molecules with Distinct Phase Regulation Behaviors
Journal
ACS Applied Materials and Interfaces
Journal Volume
14
Journal Issue
7
Pages
9587-9596
Date Issued
2022
Author(s)
Abstract
In this study, two natural small molecules, α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD), are used as additives to improve the performance of quasi-2D PEA2Csn-1PbnBr3n+1 (n = 3, herein) PeLEDs. Both of them are shown to efficiently passivate the quasi-2D perovskite films to afford improved film quality and morphology, but they exhibit distinct phase regulation behaviors possibly due to their different pore sizes. It reveals that α-CD effectively suppresses the formation of the low-n phases (n ≤ 2), while β-CD better regulates the phase with a medium-n value (n = 3). Because of effectively suppressing the formation of low-n phases, the CD-assisted quasi-2D perovskite films possess facilitated exciton energy transfer and reduced nonradiative recombination. Consequently, the optimized α-CD-derived PeLED shows the highest luminance (Lmax) of 37,825 cd/m2 with an external quantum efficiency (EQE) of 3.81%, while the β-CD-derived PeLED delivers a lower Lmax of 24,793 cd/m2 with an EQE of 3.09%. Compared to the pristine device, Lmax is enhanced by 6.3 and 3.8 times for α-CD-and β-CD-based PeLEDs, respectively, and EQE is enhanced by ∼4.8 times for both devices; besides, both CD-assisted devices also exhibit improved color purity and a lower bias dependency of electroluminescent intensity. © 2022 American Chemical Society.
Subjects
color purity; light-emitting diodes; natural cyclic molecules; phase regulation; quasi-2D perovskite
Other Subjects
Additives; Energy transfer; Light emitting diodes; Molecules; Perovskite; Pore size; Color purity; Cyclic molecules; External quantum efficiency; Lightemitting diode; Natural cyclic molecule; Performance; Perovskite films; Quasi-2d; Quasi-2d perovskite; α-cyclodextrins; Cyclodextrins
Type
journal article