Synthesis‐Kinetics of Violet‐ and Blue‐Emitting Perovskite Nanocrystals with High Brightness and Superior Stability toward Flexible Conversion Layer

Abstract

The low photoluminescence (PL) efficiency and unstable features of small blue-emitting CsPbX₃ nanocrystals (NCs) greatly limit their applications in optoelectronics field. Herein, the synergistic and post-treatment kinetics are studied to create highly bright and anomalous stable violet (peak position of ≈408 nm) and blue (peak position of ∼ 466 nm) emitting perovskite NCs. Ligand and ion exchange mechanism are systematic studied by the evolution of absorption, PL, and fluorescence lifetime to evaluate ligand bonding, defect engineering, and non-radiative recombination. Didodecyl dimethyl mmonium chloride (DDAC) and CuX₂ post-synergistic treatment created DDAC-CsPbCl₃-CuCl₂ and DDAC-CsPbCl₃-CuBr₂ NCs that remained the phase composition, morphology, and size of CsPbCl₃ NCs. The PL efficiencies are drastically increased to 42 and 85% for violet- and blue-emitting NCs, respectively. The stability test indicated that the NCs enable against various harsh conditions (e.g., ultraviolet light irradiation and heat-treatment). The NCs retained their initial PL efficiency after 2 months under ambient conditions and UV light irradiation. These NCs also exhibited high stability after heat-treatment at 120 °C. The emitting NCs embedded in flexible films still revealed bright PL and high stability, suggesting current results provide a new avenue for the application in the field of optoelectronics.