In-situ pulsed laser induced growth of CdS nanoparticles on ZnO nanorods surfaces

Herein we present a process for the in-situ growth of CdS nanoparticles using a pulsed laser irradiation. A Nd-YAG laser was applied to ZnO nanorods previously submerged in an aqueous precursor solution containing cadmium chloride and thiourea. For optimum values of the laser fluence, around 40 mJ/cm2 it was possible to fabricate a highly homogeneous film of CdS nanoparticles covering the ZnO nanorods surface. Cathodoluminescence measurements of the ZnO/CdS structure show the quenching of the ZnO yellow and green luminescence, indicating the ZnO surface defects passivation by CdS nanostructures. Although lasers have been already used for inducing growth in solution, this work presents new evidence of in-situ growth on the surface of nanostructured materials. The laser based technique presented is simple, easy to implement, scalable and it could be applied in the fabrication of nanostructured solar cells and other devices

High Efficiency CdTe/CdS Thin Film Solar Cells with a Novel Back Contact

The back contact is probably the most critical step in the fabrication of high efficiency CdTe/CdS thin film solar cells. Usually, it is done first by etching the CdTe surface in order to form a Te rich surface and second by depositing a small amount of Cu, on the order of 2nm, on top of etched CdTe surface. In this way a CuxTe layer forms that seems to behave as a non rectifying contact for CdTe. If more copper is used, there is the risk that Cu in excess diffuses into the CdTe/CdS structure causing shunt paths by segregating into the grain boundaries or lowering the cell efficiency by doping CdS thus increasing its resistivity. In this paper, we propose a novel approach to avoid the Cu diffusion. First of all we do not etch the CdTe surface, second we deposit on top of a not etched surface 100-200nm of a buffer layer, that is As2Te3, followed by the deposition of 10-20nm of Cu. If the deposition of Cu is done at 150-200\ub0C substrate temperature, a reaction between Cu and As2Te3 happens that forms a CuxTe layer by a substitution reaction. This type of contact resulted to be stable and non rectifying

Temperature dependent seeding effects on hydrothermally grown zinc oxide nanorods: Towards low temperatures and high scalability

The influence of temperature and deposition cycles on the seeding process for producing CBD grown ZnO nanorod arrays was investigated. We correlate seed sizes and distribution with the morphology of the resulting ZnO nanorod arrays. We varied the annealing temperature of the seed layer between 250°C and 500°C and found that annealing temperatures around 350°C result in the most highly oriented nanorods on glass substrates

Controlled Morphology of ZnO Nanorods for Electron Transport in Squaraine Bulk-Hetero Junction Solar Cells With Thick Active Layers

The influence of ZnO seed layer thickness in Squaraine (SQ) is investigated: PC71BM bulk heterojunction solar cells that incorporate ZnO nanorods. The thickness of the ZnO seed layer varies between 16–249 nm by changing the concentration of the precursor solution. With atomic force microscopy (AFM), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) studies, it is shown that this approach allows to systematically tune the thickness of the ZnO seed layer without influencing seed layer grain size, or the morphology of the ZnO nanorods that are deposited on top of the seed layer. The proof-of-concept is demonstrated in SQ:PC71BM solar cells. It is found that seed layers with 55 nm thickness yield the highest short circuit current densities, resulting in power conversion efficiencies of 2.5 ± 0.1%. These results are compared to SQ:PC71BM solar cells prepared in planar architectures, and it is observed that both device architectures yield comparable results. The optimized nanostructured ZnO electrode enables the fabrication of BHJ devices with thick active layers without the loss in solar cell performance

Medical thoracoscopy in respiratory medicine: The Liège University Hospital experience

Introduction: The incidence of pleural disease continues to increase worldwide. Medical thoracoscopy remains the standard method for exploration of the pleural cavity. Method: We report the retrospective evaluation, the efficacy and the observed complications in 1024 medical thoracoscopies undertaken in the University Hospital of Liège between 2000 and 2017. Results: In total, 100 pneumothoraces and 400 benign and 501 malignant pleural diseases were identified. The main indication for thoracoscopy remains the diagnosis of an exudative, lymphocytic pleural effusion of unknown aetiology after thoracocentesis. The diagnostic sensibility of thoracoscopy was 99.2% in distinguishing benign from malignant pleural disease. Talc pleurodesis was performed in 69.5% of the total population and in 66.1% of pleural effusions or thickening. Failure of pleurodesis was observed in 11% of the patients with recurrent pneumothorax and in 7.8% of neoplastic pleural effusion. We report a mortality of 0.6% in the 30 days post procedure, long duration of drainage in 8.3% and serious complications in 4.7%. In 22/1024 (2.1%) thoracoscopic evaluation was not feasible because of dense pleural fibrosis. Conclusion: Medical thoracoscopy is a safe, well-tolerated procedure with high accuracy in the diagnostic and therapeutic management of pleural disease. © 2019 SPL