Ligand Engineering for Precise Control of Ultrathin CsPbI <sub>3</sub> Nanoplatelet Superlattices for Efficient Light‐Emitting Diodes
Abstract
ABSTRACT Strongly‐confined perovskite nanoplatelets (PeNPLs) offer opportunities not found in conventional isotropic nanocubes, especially in producing linearly polarized light, as well as enhancing outcoupling through control over the transition dipole moment. But this requires ultrathin nanoplatelets with three or fewer monolayers of PbI 6 octahedra across the thickness, which are challenging to synthesise uniformly, and their luminescence is strongly affected by surface defects. Together, these limit the performance of ultrathin PeNPLs in light‐emitting diodes (LEDs). Here, we address these challenges with an ancillary ligand engineering strategy. We demonstrate that ligands with phosphoryl functional groups strongly bind to the perovskite surface, while having an organic backbone that is not sterically bulky ensures high ligand density. By modulating nucleation and growth, these ancillary ligands lead to monodisperse PeNPLs that stack more uniformly when self‐assembled into superlattices, with suppressed agglomeration. As a result, from edge‐up PeNPL superlattices, we achieve an enhanced degree of polarization, while from face‐down PeNPL superlattices, we achieve enhanced outcoupling that results in LEDs with 13.1% external quantum efficiency, the highest reported for ultrathin PeNPL LEDs. This work establishes ancillary ligand‐induced synthesis as a decisive route to achieve uniform nanoplatelets with robust orientation control, enabling full utilization of the multifunctionality of anisotropic PeNPLs.
Article Details
Authors (24)
Jongbeom Kim
Department of Materials Science and Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea
Woo Hyeon Jeong
Junzhi Ye
Allison Nicole Arber
Department of Materials University of Oxford Oxford UK
Vikram
Department of Materials University of Oxford Oxford UK
Donghan Kim
School of Electronic and Electrical Engineering, Kyungpook National University 1 , Daegu 41566,
Yi‐Teng Huang
Inorganic Chemistry Laboratory University of Oxford Oxford UK
Yixin Wang
State Key Laboratory of Molecular Engineering of Polymers
Dongeun Kim
Department of Materials Science and Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea
Dongryeol Lee
Department of Materials Science and Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea
Chia‐Yu Chang
Sustainable Electrochemical Energy Development Center (SEED Center) National Taiwan University of Science and Technology Taipei Taiwan
Xinyu Shen
Sung Yong Bae
Inorganic Chemistry Laboratory University of Oxford Oxford UK
Ashish Gaurav
Inorganic Chemistry Laboratory University of Oxford Oxford UK
Ye In Kim
Department of Materials Science and Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea
Jinkyu Yang
Department of Materials Science and Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea
Boseung Je
Department of Materials Science and Engineering Pohang University of Science and Technology (POSTECH) Pohang Republic of Korea
Changsoon Cho
Department of Materials Science and Engineering Pohang University of Science and Technology (POSTECH) Pohang Republic of Korea
Akshay Rao
Henry J. Snaith
M. Saiful Islam
Bo Ram Lee
School of Advanced Materials Science and Engineering
Myoung Hoon Song
Department of Materials Science and Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Republic of Korea
Robert L. Z. Hoye