In the series of the layered highT_c superconductors (A)_1,2 B₂Ca_n−1Cu_nO_2n+3,4 (A=Tl or Bi;B=Ba or Sr), withn=number of consecutive Cu-O layers, the electron energy states of some of the Tl-based systems have been investigated. The electron and phonon dispersion curves have been obtained. The electronic states near the Fermi level are dominated by the hybridized Cu(d) and the O(p) orbitals. The dispersion curves are highly two-dimensional with very small dispersion alongc-axis. The number of bands is enhanced with increase in the number of the consecutive Cu-O planes (n). The present results agree with those obtained earlier for other superconducting phases. The phonons are overall dominated by the vibrations of the light mass oxygen atom modes both lying in or outside the Cu-O planes. The low-frequency phonons involve the motions of the heavier Tl, Ba atoms etc.

The biohybrid photoelectrodes have been studied for photovoltaic applications. The hybrid solar cells were prepared using natural dyes and sputtered zinc oxide (ZnO) thin films on fluorine-doped tin oxide substrate. The natural dyes were extracted from basil (tulsi) leaves, spinach, thor (chhitar thor opuntia or prickly pear), pomegranate and sunflower. The dye-modified photoelectrodes expands the light absorbance of the solar spectrum. They have shown an enhancement in photocurrent and photovoltage under illumination relative to the unmodified photoelectrodes. The photovoltage and photocurrent of hybrid cells were measured to test the devices under light in active area of 1${\times}$1 cm$^2$. The hybrid solar cells have achieved solar energy conversion efficiency from 0.01 to 0.1%. Hybrid solar cells may lead to inexpensive and environment friendly solar energy conversion applications, such as solar electricity and solar fuels.