Bright Structural‐Phase‐Pure CsPbI3 Core‐PbSO4 Shell Nanoplatelets With Ultra‐Narrow Emission Bandwidth of 77 meV at 630 nm

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 49; pp. e2404573 - n/a
• Main Authors: Tsai, Ping‐Hsun, Liao, Tzu‐Hao, Chuang, Yung‐Tang, Jan, Pei‐En, Lin, Hao‐Cheng, Tan, Guang‐Hsun, Hsiao, Kai‐Yuan, Lu, Ming‐Yen, Lai, Hoong‐Lien, Chiu, Po‐Wei, Sun, Sheng‐Yuan, Li, Yun‐Li, Lin, Hao‐Wu
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.12.2024
• Subjects: Brightness; Color; core–shell; CsPbI3; Homogeneity; inorganic halide perovskite; Light emitting diodes; nanoplatelets; Perovskites; Photoluminescence; Platelets (materials); Quantum confinement; Quantum efficiency; rec. 2020 pure red; Shells (structural forms); Spectral emittance; Stability; structural phase‐pure; Thickness; Visual perception
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202404573

Achieving a narrow emission bandwidth is long pursued for display applications. Among all primary colors, obtaining pure red emission with high visual perception is the most challenging. In this work, CsPbI3 halide perovskite nanoplatelets (NPLs) with rigorously controlled 2D  [PbI6]4− octahedron layer number (n) are demonstrated. A perovskite core‐PbSO4 shell structure is designed to prevent aggregation and fusion between NPLs, enabling consistent thickness and quantum confinement strength for each NPL. Consequently, exact n = 4 CsPbI3 NPLs are demonstrated, exhibiting emission peaks around 630 nm, with very narrow spectral bandwidths of <24 nm and high absolute photoluminescence quantum yields up to 85%. The emission of n = 4 NPLs falls exactly within the pure‐red region, closely aligning with the International Telecommunication Union Recommendation BT.2020  standard. Measurements suggest predominant stability and color homogeneity compared to traditional red‐emitting CsPbIxBr3−x nanocrystals. Finally, proof‐of‐concept pure‐red emissive light‐emitting diodes (LEDs) are demonstrated by integrating n = 4 CsPbI3 NPLs films with a blue LED chip, showing an excellent external quantum efficiency of 18.3% and high brightness exceeding 3 × 106 nits. Stringent requirements for future display technologies, are satisfied based on the high color purity, stability, and brightness of CsPbI3 NPLs. The “core” of innovation with the “shell” of satisfaction. A highly stable and emissive CsPbI3 nanoplatelet‐core‐PbSO4‐shell structure is designed. The  [PbI6]4‐ octahedron layer number (n) = 4 CsPbI3 nanoplatelets exhibit an ultra‐thin emission bandwidth of 77 meV (24 nm) at 630 nm, a photoluminescence quantum yield of 85%, and superior photo‐, thermal, and long‐term stability.