Universal materials for high performance violet-blue OLEDs (CIEy < 0.06) and PhOLEDs

• Published in: Dyes and pigments 2019-04, Vol.163, p.213-220
• Main Authors: Wang, Zhong-Yi, Zhao, Jue-Wen, Liu, Bin, Cao, Chen, Li, Peng, Tong, Qing-Xiao, Tao, Si-Lu
• Format: Article
• Language: English
• Subjects: Deep-blue; Organic light-emitting diodes; Phenanthroimidazole; Twisted intramolecular charge-transfer; Universal materials
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2018.11.058

Deep blue emitters with good stability, high quantum yield, high triplet energy, and good carrier transporting properties are crucial for full color display and white solid lighting. To solve this, We designed, synthesized and characterized two bipolar deep-blue emitters 2-(4-(9,9′-spirobi[fluoren]-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (2-PPISBF) and 2-(4-(9,9′-spirobi[fluoren]-4-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (4-PPISBF). Both the materials show good stability, high quantum yield and high triplet energy. Equipped with their bipolar properties, 2-PPISBF and 4-PPISBF based non-doped devices show impressive performance with maximum external quantum efficiency (EQE) of 4.78% and 5.29% along with desirable color purity of CIE color coordinates of (0.154, 0.105) and (0.155, 0.058) respectively. Interestingly, the high triplet energy allows them to be used as a host for PhOLEDs. High performance green PhOLEDs based on 4-PPISBF show the maximum EQE, CE and PE of 16.79%, 64.09 cd/A and 67.92 l m/W respectively. And, high performance red PhOLEDs based on 2-PPISBF and 4-PPISBF were also achieved with the maximum EQE of 13.07% and 14.83%, respectively. Furthermore, 4-PPISBF-based WOLED shows high efficiencies with EQEmax of 12.27%, CEmax of 27.78 cd/A and PEmax of 32.68 l m/W. An efficient white OLED with CIE coordinates of (0.367, 0.305) which is slightly deviated from the values of the theoretical white point (0.33, 0.33) was obtained. [Display omitted] •Two deep-blue bipolar universal materials were designed and synthesized.•Non-doped blue OLED based on 2-PPI-SBF and 4-PPI-SBF achieved EQE up to 4.78% and 5.29%, respectively.•The red PhOLEDs using 4-PPI-SBF as host achieved the maximum EQE of 14.83%.