Speaker：Dr. Xiaoliang Zheng , Akron Polymer Systems

Title: Optical compensation films: screening and design of polymer

Invited by Prof. Xuehui DONG

Time：June 10, 2022 (Friday 9:30 am)

Venue: Lecture Room 324, AISMST (Building #2, KeJiYuan, North Campus)

Online：Tencent Conference 230-377-809

Faculties and students are warmly welcome.

Abstract:

Liquid crystal display (LCD) technology was invented as a result of the combination of polarized light technology and liquid crystal technology. The application and industrialization of LCD is also dependent on another technology: optical compensation film. The use of optical compensation film has greatly improved the quality of LCD, helping it emerge from other display technologies. In addition, organic light-emitting diode (OLED) display technology has also been vastly developed in recent years and is replacing liquid crystal display technology in some fields. As we know one of the main applications of OLED is being used as cell phone screens. To solve the reflection problem and to improve the display quality, OLED needs to utilize polarizer and optical compensation film likewise. Generally speaking, optical compensation film is currently one of the critical technologies for display technology.

Polymer-based transparent films are a main types of optical compensation films. They are typically prepared by solution coating or melt extrusion and their optical properties can be modified by stretching. The two refractive indices in the film plane which are perpendicular to each other are equal, but different from the refractive index in the normal direction of the film (n_x = n_y ≠ n_z). The film with an in-plane refractive index higher than the normal refractive index is called a C- plate, while the film with a normal refractive index higher than the in-plane refractive index is called a C+ plate. The type of compensation film obtained by solution coating (maybe C-/C+, or isotropic) usually depends on the structure of the polymer, which is an intrinsic property. The polymers used as C- plate are more common, such as polyesters and polyimides, etc. However, the polymers used as C+ plate are relatively rare, and their birefringence values are generally too small to be suitable for optical compensation film. This lecture will focus on the screening and design of the polymer used as C+ plate.

Content.

Introduction to Polarized Light

Introduction to LCD

Introduction to optical compensation film

Screening and design for the polymer used as C+ plate

Brief Biography：

Dr. Xiaoliang Zheng graduated from Peking University with a B.S. in Chemistry and an M.S. in Polymer Science, and then joined the research group of Prof. Stephen Z. D. Cheng in the Department of Polymer Science at the University of Akron, where he received his Ph.D. in 2005. He then joined Akron Polymer Systems, where he has been engaged in the development of new high-performance polymers for a long time. He is currently the chief scientist of the company.

The development and industrialization of optical polymer films is one of the main research interests of Dr. Zheng. A type of polymer for optical compensation films developed by him has been successfully industrialized (annual production and sales of nearly 100 tons) and take a leading position in this field. He has received 24 patents in the field of optical compensation films and was awarded the Innovation and Invention Award by Akron Polymer Systems in 2014 for his breakthrough work on C+ plate.