城戸・笹部・千葉研究室の高橋佳人さん(2019年卒業)と千葉貴之助教のペロブスカイトナノ結晶の分散安定性に関する論文がACS Applied Materials & Interfaces (IF: 8.330)に掲載されました。
Surface Crystal Growth of Perovskite Nanocrystals via Postsynthetic Lead(II) Bromide Treatment to Increase the Colloidal Stability and Efficiency of Light-Emitting Devices
Takayuki Chiba,* Yoshihito Takahashi, Jun Sato, Shota Ishikawa, Hinako Ebe, Kota Tamura, Satoru Ohisa, and Junji Kido*
The surface modification of metal halide perovskite nanocrystals (NCs) significantly impacts their optical properties and colloidal stability. This subsequently affects the performance of light-emitting devices (LEDs). Therefore, numerous surface passivation techniques like ligand exchange and metal halide doping have been explored to passivate the surface defects of perovskite NCs and obtain highly efficient LEDs. In this study, we demonstrated the post-synthetic metal halide doping treatment using lead (II) bromide (PbBr2) to passivate the surface defects of the CsPbBr3 NCs at a moderate reaction temperature of 80 °C. The alkyl quaternary ammonium salt, didodecyldimethylammonium bromide (DC12AB), enabled the complete dissolution of PbBr2 in a non-polar solvent, toluene. Due to surface crystal growth, the particle sizes of the PbBr2-doped CsPbBr3 NCs were higher than that of the as-synthesized CsPbBr3 NCs. The photoluminescence quantum yield (PLQY) of the CsPbBr3 NCs drastically increased from 26.8% to 83.9% after the PbBr2 doping treatment. Moreover, the PbBr2-doped CsPbBr3 NCs possessed long-term colloidal stability of more than 2 months that indicated the strong bonding between the NCs and ligands. We observed that the alkyl chain length of the quaternary alkyl ammonium salts affected the luminance and device stability during operations. In this study, a promising strategy was devised to achieve highly luminescent perovskite NCs with excellent colloidal stability that can enhance the performance of LEDs.