Synthesis and luminescent properties of terbium complex containing 4-benzoylbenzoic acid for application in NUV-based LED

A novel Tb（III） ternary complex Tb（p-BBA）_3MAA was synthesized with 4-benzoylbenzoic acid（p-BBA） and methacrylic acid（MAA） as ligands. The complex was characterized by IR, UV-visible, thermogravimetric analysis and fluorescence spectroscopy. Monitored at 544 nm, the complex displayed wide and strong excitation band at 300–400 nm, which matched well with the 365 nm-emitting UV chip. The complex exhibited excellent green emission at 544 nm（~5D_4→~7F_5 transition of Tb~（3＋）） under an excitation at 365 nm. Besides, the complex showed high thermal stability. Its intramolecular energy transfer process was further discussed. Furthermore, the complex also had higher fluorescence lifetime（1.38 ms） and higher quantum yield（0.372）. Finally, electroluminescent properties indicated that when used to fabricate LED with 365 nm UV chip（power efficiency is 18.6 lm/W）, the complex remained its favorable optical performance. These results implied that Tb（p-BBA）_3MAA could be used as a green phosphor for NUV-based white LED.