title: Exotic Property of Azobenzenesulfonic Photoalignment Material Based on Relative Humidity.
abstract: Azobenzene photoalignment materials are highly effective for liquid crystal alignment with high sensitivity and rewritability. A strong relationship between relative humidity and the alignment quality of a thin layer of azobenzenesulfonic dye has been investigated, where the photoinduced phase retardation, order parameter, and anchoring strength of the alignment layer are influenced dramatically by relative humidity. Our results provide fabrication guidance for the photoalignment process in both display and photonic applications. In addition, an exotic substantial ordering enhancement is observed by increasing the relative humidity without further light illumination, where the self-assembly of the photoaligned material incorporated with water molecules is the underlying reason for the enhanced high ordering (S > 0.8). Based on X-ray diffraction and depolarized optical microscopy observation, together with the photoalignment quality, a semicrystalline structure of the humidified azobenzenesulfonic material is proposed. The transition from amorphous solid at low relative humidity to semicrystal at high relative humidity provides a new perspective of understanding the hydrophilic photoalignment materials.
authors.affiliation: Department of Electrical and Electronic Engineering, Southern University of Science and Technology , No. 1088, Xueyuan Road, Xili, Nanshan District, Shenzhen, Guangdong 518055, People's Republic of China.|School of Physics, Nankai University , Tianjin 300071, People's Republic of China.|State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Shi
authors.affiliation: State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Chenxiang
authors.initials: C
authors.lastname: Zhao
authors.affiliation: State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Jacob Yeuk-Lung
authors.initials: JY
authors.lastname: Ho
authors.affiliation: State Scientific Institution "Institute for Single Crystals", Lenin Avenue, 60, Kharkov 61001, Ukraine.
authors.forename: Valery V
authors.initials: VV
authors.lastname: Vashchenko
authors.affiliation: State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Abhishek Kumar
authors.initials: AK
authors.lastname: Srivastava
authors.affiliation: State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Chigrinov
authors.affiliation: State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Hoi-Sing
authors.initials: HS
authors.lastname: Kwok
authors.affiliation: School of Physics, Nankai University , Tianjin 300071, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Song
authors.affiliation: Department of Electrical and Electronic Engineering, Southern University of Science and Technology , No. 1088, Xueyuan Road, Xili, Nanshan District, Shenzhen, Guangdong 518055, People's Republic of China.
authors.forename: Dan
authors.identifier: 0000-0003-2117-0570
authors.initials: D
authors.lastname: Luo