Kriti Sharma

Radiation Induced Effects on Properties of Semiconducting Nanomaterials

The irradiation of nanomaterials with energetic particles has significant effects on the properties of target materials. In addition to the well-known detrimental effects of irradiations, they have also some beneficial effects on the properties of nanomaterials. Irradiation effect can change the morphology of the materials in a controlled manner and tailor their mechanical, structural, optical and electrical properties. Irradiation induced modifications in the properties of nanomaterials can be exploited for many useful applications. With the aim of getting better performance of electronic devices, it is necessary to discuss the irradiation induced changes in the nanomaterials. In order to improve the irradiation hardness of electronic components, it is also crucial to have a fundamental understanding of the impact of the irradiation on the defect states and transport properties of the host material. In the present article, we review some recent advances on the irradiation induced effects on the properties of semiconducting nanomaterials. We have reviewed the effect of different types of irradiations which includes γ-irradiation, electron beam irradiation, laser irradiation, swift heavy ion irradiations, thermal induced, and optical induced irradiations, etc. on the various properties of semiconducting nanomaterials. In addition, the irradiation induced defects are also discussed.

Study of sub gap optical absorption parameters in Pb doped CdSe thin films

Thin films of Pb doped CdSe have been prepared by thermal evaporation technique using inert gas condensation method. Constant photocurrent method is used to determine absorption coefficient in the low energy region. The absorption coefficient in the sub gap region follows an exponential Urbach tail. The value of Urbach energy increases after Pb doping in CdSe which indicates increase in structural disorder in the material. Energetic distribution of occupied density of states is calculated from sub gap absorption spectra using derivative procedure. The number density of defect states of thin films has also been calculated from Urbach energy.

Thermally induced effect on sub-band gap absorption in Ag doped CdSe thin films

Thin films of Ag doped CdSe have been prepared by thermal evaporation using inert gas condensation (IGC) method taking Argon as inert gas. The prepared thin films are annealed at 363 K for one hour. The sub-band gap absorption spectra in the as deposited and annealed thin films have been studied using constant photocurrent method (CPM). The absorption coefficient in the sub-band gap region is described by an Urbach tail in both as deposited and annealed thin films. The value of Urbach energy and number density of trap states have been calculated from the absorption coefficient in the sub-band gap region which have been found to increase after annealing treatment indicating increase in disorderness in the lattice. The energy distribution of the occupied density of states below Fermi level has also been studied using derivative procedure of absorption coefficient.

Progress in Plasmonic Enhanced Bulk Heterojunction Organic/Polymer Solar Cells

To reduce the cost of solar electricity, there is an enormous potential of thin-film photovoltaic technologies. An approach for lowering the manufacturing costs of solar cells is to use organic (polymer) materials that can be processed under less demanding conditions. Organic/polymer solar cells have many intrinsic advantages, such as their light weight, flexibility, and low material and manufacturing costs. But reduced thickness comes at the expense of performance. However, thin photoactive layers are widely used, but light-trapping strategies, due to the embedding of plasmonic metallic nanoparticles have been shown to be beneficial for a better optical absorption in polymer solar cells. This article reviews the different plasmonic effects occurring due to the incorporation of metallic nanoparticles in the polymer solar cell. It is shown that a careful choice of size, concentration and location of plasmonic metallic nanoparticles in the device result in an enhancement of the power conversion efficiencies, when compared to standard organic solar cell devices.Contents of Paper