Enhancing the Performance of Quasi-2D Perovskite Light-Emitting Diodes Using Natural Cyclic Molecules with Distinct Phase Regulation Behaviors

Chiung-Han Chen; Yen-Hung Kuo; Yu-Kuan Lin; I-Chih Ni; Bi-Hsuan Lin; Chih-I Wu; Hin-Lap Yip; Chi-Ching Kuo; Chu-Chen Chueh

doi:10.1021/acsami.1c23594

Enhancing the Performance of Quasi-2D Perovskite Light-Emitting Diodes Using Natural Cyclic Molecules with Distinct Phase Regulation Behaviors

ACS Appl Mater Interfaces. 2022 Feb 23;14(7):9587-9596. doi: 10.1021/acsami.1c23594. Epub 2022 Feb 10.

Authors

Chiung-Han Chen^{1

2}, Yen-Hung Kuo³, Yu-Kuan Lin¹, I-Chih Ni⁴, Bi-Hsuan Lin⁵, Chih-I Wu⁴, Hin-Lap Yip⁶, Chi-Ching Kuo³, Chu-Chen Chueh^{1

2}

Affiliations

¹ Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
² Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei 10617, Taiwan.
³ Insitute of Organic and Polymeric Material, National Taipei University of Technology, Taipei 10617, Taiwan.
⁴ Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
⁵ National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
⁶ Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon 999077 Hong Kong, P. R. China.

PMID: 35142213
DOI: 10.1021/acsami.1c23594

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 PEA₂Cs_n-1Pb_nBr_3n+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 (L_max) of 37,825 cd/m² with an external quantum efficiency (EQE) of 3.81%, while the β-CD-derived PeLED delivers a lower L_max of 24,793 cd/m² with an EQE of 3.09%. Compared to the pristine device, L_max 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.

Keywords: color purity; light-emitting diodes; natural cyclic molecules; phase regulation; quasi-2D perovskite.