Despite its exceptional optical absorptivity, suitable band gap, and earth abundance, the low open-circuit voltage of pyrite FeS2 has remained the biggest challenge preventing its use in photovoltaic devices. Two widely-accepted causes are: (i) Fermi level pinning caused by intrinsic surface states that appear as gap states; (ii) presence of the polymorph marcasite. Based on density-functional ...

Absolute photonic band gaps in two-dimensional square and honeycomb lattices of circular crosssection rods can be increased by reducing the structure symmetry. The addition of a smaller diameter rod into the center of each lattice unit cell lifts band degeneracies to create significantly larger band gaps. Symmetry breaking is most effective at filling fractions near those which produce absolute...

nanoparticles of zirconium(iv) tungstate are prepared by chemical co-precipitation method. thecharacterizations have been carried out by tg/dta, dsc, afm, xrd, ftir and uv-vis spectrum. plspectrum shows two emission bands at 350 nm and at 477 nm. the effects of frequency on the dielectricbehavior and ac electrical conductivity have been studied. the dielectric constant is found to be 119.43 at1...