Although bismuth chalcohalides, such as BiSI and BiSeI, have been recently attracting considerable attention as photovoltaic materials, the methods available to synthesize them are quite limited thus far. In this study, a novel, facile method to synthesize these chalcohalides, including BiSBr1-xIx solid solutions, at low temperatures was developed via the substitution of anions from O2- to S2- or Se2- using bismuth oxyhalide precursors. This method was also applied for synthesizing BiSBr1-xIx, where continuous changes in their band gaps were observed depending on the ratio between iodine and bromine. The composition of all elements except oxygen in the chalcohalides thus produced was almost identical to that of the oxyhalide precursors, attributed to the suppressed volatilization of halogens at such low temperatures. All chalcohalides loaded on FTO clearly exhibited an anodic photocurrent in an acetonitrile solution containing I-, attributed to their n-type nature, e. Bismuth-based non-oxide compounds, such as halides e.
Bismuth-based nanoribbons show ‘topological’ transport, potential for new technologies
Band gap - Wikipedia
Recently phosphorene, monolayer honeycomb structure of black phosphorus, was experimentally manufactured and attracts rapidly growing interests. Here we investigate stability and electronic properties of honeycomb structure of arsenic system based on first principle calculations. Two types of honeycomb structures, buckled and puckered, are found to be stable. We call them arsenene as in the case of phosphorene. We find that both the buckled and puckered arsenene possess indirect gaps.
Advantages And Disadvantages Of Semiconductors
In solid-state physics , a band gap , also called an energy gap , is an energy range in a solid where no electronic states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference in electron volts between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. It is the energy required to promote a valence electron bound to an atom to become a conduction electron , which is free to move within the crystal lattice and serve as a charge carrier to conduct electric current.
Photonic Crystal Research About half of our group is dedicated to working on problems related to a new kind of material, photonic crystals also known as photonic band-gap materials. Photonic crystals are periodic dielectric structures that have a band gap that forbids propagation of a certain frequency range of light. This property enables one to control light with amazing facility and produce effects that are impossible with conventional optics.