From Dopant to Host: Solution Synthesis and Light‐Emitting Applications of Organic‐Inorganic Lanthanide‐Based Metal Halides
Tianxin Bai, Qiujie Wang, Yunfei Bai, Qichao Meng, Hongyuan Zhao, Ziying Wen, Haibo Sun, Lixin Huang, Junke Jiang, Dan Huang, Feng Liu, William W. Yu
Abstract
The rich and unique energy level structure arising from 4f n inner shell configuration of trivalent lanthanide ions (Ln 3+ ) renders them highly attractive for light‐emitting applications. Currently, research primarily focuses on Ln 3+ doping in either traditional garnets or the recently developed perovskite phosphors. However, there have been few reports on stable phosphors crystallized with pure lanthanide elements. Herein, a universal solution‐based route to eight Ln 3+ ‐based metal halides from the organic‐inorganic A 4 LnX 7 family is described, where A + = 4,4‐difluoropiperidinium (DFPD + ), Ln 3+ = Nd 3+ , Eu 3+ , Ho 3+ , Sm 3+ , Tm 3+ , Tb 3+ , Yb 3+ , Er 3+ , and X − = Cl − , Br − . Visible photoluminescence (PL) is observed from Tb 3+ ‐, Eu 3+ ‐, Ho 3+ ‐, and Sm 3+ ‐based compounds with Tb and Eu compositions exhibiting high PL quantum yields of 90–100%; Nd 3+ ‐, Tm 3+ ‐, Yb 3+ ‐, and Er 3+ ‐based crystals show fascinating near‐infrared emission. Light‐emitting diodes (LEDs) fabricated with (DFPD) 4 TbCl 7 yield characteristic emission of Tb 3+ , representing the first demonstration of electroluminescence from these organic‐inorganic Ln 3+ ‐based metal halides. Moreover, these materials exhibit distinct excitation wavelength‐dependent emission after alloying with different Ln 3+ ions, making them interesting for multicolor display and multilevel information encryption applications. It is foreseen that this study will open up the way to a possible design of robust optoelectronic devices based on lanthanide metal halides.