Professor, Department of Polymer Materials, School of Materials Science and Engineering, Shanghai University, Shanghai, 200444, China

Biography: Dr. Ying He received her PhD degree in Materials Science from Shanghai University in 2006. Currently she is a professor at Department of Polymer Materials, School of Materials Science and Engineering, Shanghai University, Shanghai, China. Her current research interests mainly cover optoelectronic polymer materials and nanocomposites, including polymer light-emitting display material and device, self-assembly growth of polymer nanocomposites, high-power LED encapsulation adhesive, electroactive polymers, etc.

Speech Title: Synthesis and properties of high efficient room temperature phosphorescence materials PPV derivative

Aims: For the purpose of improving device efficiency and reducing cost, it is necessary to develop pure organic molecules with room temperature phosphorescence (RTP).

Methods: By a series of chemical reactions, 2,5-dibromo-1,4-bis(octyloxy)benzene (M1) and 1,4-dibromo-2,5-divinylbenzene (M2), were synthesized. Through the halogen-metal exchange reaction of M1 and M2, a high efficiency pure organic RTP polymer, PPV derivative (Br-PPV-CHO), was synthesized. All the synthesized polymers were characterized by a Bruker 500 MHz spectrometer. The electrochemical property of the PPV derivative was measured through a three-electrode system in an anhydrous acetonitrile solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF₆). The photoluminescence performance was characterized by using Fluoromax-4, FLS900, and FLS920 equipped with integrating sphere.

Results: The results show that the PPV derivative possesses a blue emission at 496 nm, an emission lifetime of 14.1 μs, and a photoluminescence quantum yield of 12.2 %. The HOMO and LUMO of the PPV derivative are -5.35 eV and -2.75 eV, respectively, showing a great potential application in the emitting layer of OLED. A device fabricated with the PPV derivative as the emitting material layer shows a max luminance of 194 cd/m² when the Br-PPV-CHO content was 0.5 wt %, demonstrating the best RTP performance.

Conclusions: We have prepared the pure organic room temperature phosphorescence material PPV derivate Br-PPV-CHO, and applied it to OLED devices. This PPV derivate was demonstrated a good room temperature phosphorescence and a relative high photoluminescence quantum yield. Although the devices based on Br-PPV-CHO show a max luminance of 194 cd/m², it still needs to optimize the devices to enhance the performance of luminance and device efficiency.