Feilong Liu

Amorphous System and Theory

South China Normal University

Science Building No. 5,  Guangzhou University Town, Panyu, Guangzhou, China 510006

Email: feilongliu@m.scnu.edu.cn

Biography

     Feilong Liu obtained his bachelor’s degree from Peking University, China and his Ph.D. degree from the University of Minnesota, United States. He was a postdoctoral researcher at Eindhoven University of Technology, the Netherlands (advisor: Prof. R. Coehoorn,  member of the Royal Netherlands Academy of Sciences). He then worked at Simbeyond B.V., the Netherlands as a significant contributor to the commercial OLED device simulation tool Bumblebee. He becomes an Associate Professor at South China Academy of Advanced Optoelectronics at South China Normal University since 2021.

Abstract for Presentation

Advanced modeling of OLEDs: physics and applications

    Organic light-emitting devices (OLED) are one of the key technologies in display applications such as mobile phones, automobiles, and wearable devices. At present, research and development (R&D) of new materials and device architectures mainly rely on trial-and-error approaches. Understanding the dynamics of charges and excitons inside an OLED as well as developing quantitative and predictive physical models from materials to devices are key to further R&D improvement. In physics, an OLED is an amorphous system composed of disordered organic small molecules. On the one hand, the disorder nature of a large number of noncrystalline molecular assembly must be considered and has a decisive impact on the properties of the device. Therefore, material calculation methods such as quantum chemistry are insufficient to cover the mesoscopic (100 nm) scale of actual OLEDs. On the other hand, physical models based on macroscopic continuum assumptions (such as drift-diffusion) neglect the discreteness of molecules and the incoherent hopping of localized electrons between molecules. In this presentation, I will systematically introduce the development of physical theories and advanced modeling of OLEDs, starting from simple formulas, to the 1st generation of one-dimensional continuous models (drift-diffusion), the 2nd generation of three-dimensional discrete models (Monte-Carlo, master-equation), and the advanced 3rd generation of multi-scale physical models from molecules to devices. I will also demonstrate the application of these physical models in predicting the experimental electrical characteristics of actual OLEDs [1-2].

Figure 1. Schematics of different generations of OLED device models [1].

a) First-generation continuum-based drift-diffusion models; b) Second-generation discreteness-based Monte Carlo or master equation models;

c) Third-generation molecule-to-device multi-scale models. Red and blue arrows: trajectories of holes and electrons in an OLED, respectively.

References

[1] F. Liu*, Y. Su, X. Lin, L. Nian, B. Wu, Q. Niu, H. van Eersel, P. A. Bobbert, R. Coehoorn*, G. Zhou*, Phys. Rev. Applied, 17 (2022) 024003.

[2] F. Liu, H. van Eersel, P. A. Bobbert, and R. Coehoorn*, Phys. Rev. Applied, 10 (2018) 054007.