Efficient blue and bluish-green iridium phosphors: Fine-tuning emissions of FIrpic by halogen substitution on pyridine-containing ligands

详细信息    查看全文

• 作者：Cong Fan ; Liping Zhu ; Bei Jiang ; Cheng Zhong ; Dongge Ma ; Jingui Qin ; Chuluo Yang
• 关键词：Halogen atoms ; Iridium compounds ; Hammett parameters ; Phosphorescent organic light-emitting diode
• 刊名：Organic Electronics
• 出版年：December, 2013
• 年：2013
• 卷：14
• 期：12
• 页码：3163-3171
• 全文大小：1065 K

文摘

Three new iridium compounds, 4-F-FIrpic, 4-Cl-FIrpic and 4-Br-FIrpic, were designed and synthesized by introducing the F, Cl and Br atoms to the 4-position of pyridine ring in the frame of sky-blue emitter, FIrpic. Adding F atom stabilizes the HOMO level of FIrpic but keeps the LUMO level of FIrpic almost unchanged, which consequently broadens the HOMO-LUMO gap of FIrpic and finely tunes the emission to 465 nm of 4-F-FIrpic from 470 nm of FIrpic. In contrast, introducing of Cl and Br atoms simultaneously lowers the HOMO and LUMO levels of FIrpic, which brings about the squeeze of HOMO-LUMO gap in FIrpic and makes the emissions of 4-Cl-FIrpic and 4-Br-FIrpic red-shift to 475 and 479 nm, respectively. The phosphorescent organic light-emitting devices using the three iridium compounds as dopants were fabricated with the following configuration: ITO/MoO₃/TAPC/TCTA:dopants/Tm/LiF/Al. The device based on 4-F-FIrpic showed a blue emission with the Commission Internationale de L鈥橢clairage coordinate of (0.15, 0.28), and revealed rather high efficiencies, with maximum current efficiency of 29 cd A^鈭?, power efficiency of 29 lm W^鈭? and external quantum efficiency of 14.6%.