Chen C.-HKuo Y.-HLin Y.-KNi I.-CLin B.-HCHIH-I WUYip H.-LKuo C.-CCHU-CHEN CHUEH2022-11-162022-11-16202219448244https://www.scopus.com/inward/record.uri?eid=2-s2.0-85125093771&doi=10.1021%2facsami.1c23594&partnerID=40&md5=a581c1d8815a70e6440dc6fcd6b97f8fhttps://scholars.lib.ntu.edu.tw/handle/123456789/625464In 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.color purity; light-emitting diodes; natural cyclic molecules; phase regulation; quasi-2D perovskite[SDGs]SDG7Additives; 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; Cyclodextrinsjournal article10.1021/acsami.1c23594351422132-s2.0-85125093771