title: Green Color Purification in Tb(3+) Ions through Silica Inverse Opal Heterostructure.
abstract: The ordered SiO2:Tb(3+) inverse opal heterostructure films are fabricated through polystyrene spheres hetero-opal template using the convective self-assembly method to examine their potential for color purification. Their optical properties and photoluminescence have been investigated and compared with individual single inverse opals and reference (SiO2:Tb(3+) powder). The heterostructures are shown to possess two broad photonic stop bands separated by an effective pass band, causing suppression of blue, orange, and red emission bands corresponding to (5)D4 → (7)F(j); j = 6, 4, 3 transitions, respectively and an enhancement of green emission (i.e., (5)D4 → (7)F5). Although the suppression of various emission occurs because of its overlap with the photonic band gaps (PSBs), the enhancement of green radiation is observed because of its location matching with the pass band region. The Commission International de l'Eclairage (CIE) chromaticity coordinates of the emission spectrum of the heterostructure based on polystyrene sphere of 390 and 500 nm diameter are x = 0.2936, y = 0.6512 and lie closest to those of standard green color (wavelength 545 nm). In addition, a significant increase observed in luminescence lifetime for (5)D4 level of terbium in inverse opal heterostructures vis-à-vis reference (SiO2:Tb(3+) powder) is attributed to the change in the effective refractive index.
authors.affiliation: †Materials Science Programme, ‡Department of Chemical Engineering, §Centre for Environmental Science and Engineering, ⊥Thematic Unit of Excellence on Soft Nanofabrication, Indian Institute of Technology Kanpur, Kanpur 208016, India.
authors.forename: Vishnu Prasad
authors.initials: VP
authors.lastname: Shrivastava
authors.affiliation: †Materials Science Programme, ‡Department of Chemical Engineering, §Centre for Environmental Science and Engineering, ⊥Thematic Unit of Excellence on Soft Nanofabrication, Indian Institute of Technology Kanpur, Kanpur 208016, India.
authors.forename: Sri
authors.initials: S
authors.lastname: Sivakumar
authors.affiliation: †Materials Science Programme, ‡Department of Chemical Engineering, §Centre for Environmental Science and Engineering, ⊥Thematic Unit of Excellence on Soft Nanofabrication, Indian Institute of Technology Kanpur, Kanpur 208016, India.
authors.forename: Jitendra
authors.initials: J
authors.lastname: Kumar
keywords: color; heterostructure; inverse opal; lanthanides; photonic crystal; spontaneous emission