title: Fabrication of colloidal photonic crystal heterostructures free of interface imperfection based on solvent vapor annealing.
abstract: We describe the transformation of a colloidal photonic crystal into a photonic crystal heterostructure. It was achieved by annealing a polystyrene multilayer colloidal photonic crystal partially immersed in water using a solvent vapor. The floating polystyrene colloidal photonic crystal was divided into two parts by the liquid level, which can be manipulated by the addition of ethanol into the water. The top part protruding out of the water experienced a uniform lattice stretching upon exposure to the solvent vapor. The bottom part that stayed immersed in the water remained unaffected due to the protection by the water. The inconsistent behaviors of the two parts resulted in the formation of a colloidal photonic crystal heterostructure. Such a heterostructure was free of interface imperfection since it was a direct descendant of the original colloidal crystal. Meanwhile, optical measurements demonstrated the presence of a wider photonic band gap along the crystallographic [111] direction in these photonic crystal heterostructures compared with the original colloidal photonic crystals.
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaomiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Physics, Liaoning University, Shenyang 110036, China.
authors.forename: Duobiao
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Geng
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.
authors.forename: Lijing
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Physics, Liaoning University, Shenyang 110036, China.
authors.forename: Tianya
authors.initials: T
authors.lastname: Tan
authors.affiliation: College of Science, Guizhou University, Guiyang 550025, China.
authors.forename: Mingzhe
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China. Electronic address: yanqf@mail.tsinghua.edu.cn.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Yan
keywords: Colloidal self-assembly; Interface imperfection; Photonic crystal heterostructure; Solvent vapor annealing