title: Crystal Structure and Band Gap Engineering in Polyoxometalate-Based Inorganic-Organic Hybrids.
abstract: We have demonstrated engineering of the electronic band gap of the hybrid materials based on POMs (polyoxometalates), by controlling its structural complexity through variation in the conditions of synthesis. The pH- and temperature-dependent studies give a clear insight into how these experimental factors affect the overall hybrid structure and its properties. Our structural manipulations have been successful in effectively tuning the optical band gap and electronic band structure of this kind of hybrids, which can find many applications in the field of photovoltaic and semiconducting devices. We have also addressed a common crystallographic disorder observed in Keggin-ion (one type of heteropolyoxometalate [POMs])-based hybrid materials. Through a combination of crystallographic, spectroscopic, and theoretical analysis of four new POM-based hybrids synthesized with tactically varied reaction conditions, we trace the origin and nature of the disorder associated with it and the subtle local structural coordination involved in its core picture. While the crystallography yields a centrosymmetric structure with planar coordination of Si, our analysis with XPS, IR, and Raman spectroscopy reveals a tetrahedral coordination with broken inversion symmetry, corroborated by first-principles calculations.
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Soumyabrata
authors.initials: S
authors.lastname: Roy
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Sumanta
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Jaysree
authors.initials: J
authors.lastname: Pan
authors.affiliation: Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Umesh V
authors.initials: UV
authors.lastname: Waghmare
authors.affiliation: Chemistry and Physics of Material Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: R
authors.initials: R
authors.lastname: Dhanya
authors.affiliation: Chemistry and Physics of Material Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Chandrabhas
authors.initials: C
authors.lastname: Narayana
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India.
authors.forename: Sebastian C
authors.initials: SC
authors.lastname: Peter