Reliable and Damage-Free Estimation of Resistivity of ZnO Thin Films for Photovoltaic Applications Using Photoluminescence Technique

This work projects photoluminescence (PL) as an alternative technique to estimate the order of resistivity of zinc oxide (ZnO) thin films. ZnO thin films, deposited using chemical spray pyrolysis (CSP) by varying the deposition parameters like solvent, spray rate, pH of precursor, and so forth, have been used for this study. Variation in the deposition conditions has tremendous impact on the luminescence properties as well as resistivity. Two emissions could be recorded for all samples—the near band edge emission (NBE) at 380 nm and the deep level emission (DLE) at ~500 nm which are competing in nature. It is observed that the ratio of intensities of DLE to NBE (/) can be reduced by controlling oxygen incorporation in the sample. - measurements indicate that restricting oxygen incorporation reduces resistivity considerably. Variation of / and resistivity for samples prepared under different deposition conditions is similar in nature. / was always less than resistivity by an order for all samples. Thus from PL measurements alone, the order of resistivity of the samples can be estimated

On tuning the orientation of grains of spray pyrolysed ZnO thin films

Effect of varying spray rate on the structure and optoelectronic properties of spray pyrolysed ZnO film is analysed. ZnO films were characterised using different techniques such as X-ray diffraction (XRD), photoluminescence, electrical resistivity measurement, and optical absorption. The XRD analysis proved that, with the increase in spray rate, orientation of the grains changed from (1 0 1) plane to (0 0 2) plane. The films exhibited luminescence in two regions—one was the ‘near band-edge’ (NBE) (∼380 nm) emission and the other one was the ‘blue-green emission’ (∼503 nm). Intensity of the blue-green emission decreased after orientation of grains shifted to (0 0 2) plane. Scanning electron microscope (SEM) analysis of the films asserts that spray rate has major role in improving the crystallographic properties of the films. Moreover resistivity of the films could be lowered to 2.4×10−2 cm without any doping or post-deposition annealingCochin University of Science and TechnologyApplied Surface Science 256 (2010) 6025–602

Reliable and Damage-Free Estimation of Resistivity of ZnO Thin Films for Photovoltaic Applications Using Photoluminescence Technique

This work projects photoluminescence (PL) as an alternative technique to estimate the order of resistivity of zinc oxide (ZnO) thin films. ZnO thin films, deposited using chemical spray pyrolysis (CSP) by varying the deposition parameters like solvent, spray rate, pH of precursor, and so forth, have been used for this study. Variation in the deposition conditions has tremendous impact on the luminescence properties as well as resistivity. Two emissions could be recorded for all samples—the near band edge emission (NBE) at 380 nm and the deep level emission (DLE) at ∼500 nm which are competing in nature. It is observed that the ratio of intensities of DLE to NBE ( DLE/ NBE) can be reduced by controlling oxygen incorporation in the sample. - measurements indicate that restricting oxygen incorporation reduces resistivity considerably. Variation of DLE/ NBE and resistivity for samples prepared under different deposition conditions is similar in nature. DLE/ NBE was always less than resistivity by an order for all samples.Thus from PL measurements alone, the order of resistivity of the samples can be estimated.Cochin University of Science and TechnologyInternational Journal of Photoenergy Volume 2013, Article ID 105796, 9 page

Angiopep2-functionalized polymersomes for targeted doxorubicin delivery to glioblastoma cells

A targeted drug delivery nanosystem for glioblastoma multiforme (GBM) based on polymersomes (Ps) made of poly(dimethylsiloxane)-poly(2-methyloxazoline) (PDMS-PMOXA) diblock copolymers was developed to evaluate their potential to actively target brain cancer cells and deliver anticancer drugs. Angiopep2 was conjugated to the surface of preformed Ps to target the low density lipoprotein receptor related protein I that are overexpressed in blood brain barrier (BBB) and glioma cells. The conjugation efficiency yield for angiopep2 was estimated to be 24%. The angiopep2-functionalized Ps showed no cellular toxicity after 24 h and enhanced the cellular uptake around 5 times more in U87MG glioblastoma cells compared to the non-targeted Ps. The encapsulation efficiency of doxorubicin (DOX) in Ps was 13% by co-solvent method, compared to a film rehydration method (4%). The release profiles of the DOX from Ps showed a release of 42% at pH 5.5 and 40% at pH 7.4 after 24 h, indicating that Ps can efficiently retain the DOX with a slow release rate. Furthermore, the in vitro antiproliferative activity of DOX-loaded Ps-Angiopep2 showed enhanced toxicity to U87MG glioblastoma cells, compared to non -targeted Ps. Overall, our in vitro results suggested that angiopep2-conjugated Ps can be used as nanocarriers for efficient targeted DOX delivery to glioblastoma cells