RESUMEN
In this study, we investigated the effect of the stacking order of metal precursors on the formation of volume defects, such as blisters and nanopores, in CZTSSe thin-film solar cells. We fabricated CZTSSe thin films using three types of metal-precursor combinations, namely, Zn/Cu/Sn/Mo, Cu/Zn/Sn/Mo, and Sn/Cu/Zn/Mo, and studied the blister formation. The blister-formation mechanism was based on the delamination model, taking into consideration the compressive stress and adhesion properties. A compressive stress could be induced during the preferential formation of a ZnSSe shell. Under this stress, the adhesion between the ZnSSe film and the Mo substrate could be maintained by the surface tension of a metallic liquid phase with good wettability, or by the functioning of ZnSSe pillars as anchors, depending on the type of metal precursor used. Additionally, the nanopore formation near the back-contact side was found to be induced by the columnar microstructure of the metal precursor with the Cu/Zn/Mo stacking order and its dezincification. Based on the two volume-defect-formation mechanisms proposed herein, further development of volume-defect-formation suppression technology is expected to be made.
RESUMEN
The efficiency of thin-film chalcogenide solar cells is dependent on their window layer thickness. However, the application of an ultrathin window layer is difficult because of the limited capability of the deposition process. This paper reports the use of atomic layer deposition (ALD) processes for fabrication of thin window layers for Cu(Inx,Ga1-x)Se2 (CIGS) thin-film solar cells, replacing conventional sputtering techniques. We fabricated a viable ultrathin 12 nm window layer on a CdS buffer layer from the uniform conformal coating provided by ALD. CIGS solar cells with an ALD ZnO window layer exhibited superior photovoltaic performances to those of cells with a sputtered intrinsic ZnO (i-ZnO) window layer. The short-circuit current of the former solar cells improved with the reduction in light loss caused by using a thinner ZnO window layer with a wider band gap. Ultrathin uniform A-ZnO window layers also proved more effective than sputtered i-ZnO layers at improving the open-circuit voltage of the CIGS solar cells, because of the additional buffering effect caused by their semiconducting nature. In addition, because of the precise control of the material structure provided by ALD, CIGS solar cells with A-ZnO window layers exhibited a narrow deviation of photovoltaic properties, advantageous for large-scale mass production purposes.
RESUMEN
INTRODUCTION: Muscular weakness affecting predominantly the proximal limb muscles and neck flexors is the cardinal feature of intermediate syndrome with cranial nerve palsies occasionally accompanied. Following acute cholinergic phase of organophosphate poisoning (OPP), only a few isolated cases of vocal cord paralysis have been reported in the past. We describe a case of bilateral vocal cord paralysis which occurred in the wake of a clinical recovery from acute cholinergic crisis in OPP. CASE REPORT: A 32-year-old woman presented with severe cholinergic crisis after ingestion of an unknown amount of dichlorvos in a suicide attempt. The patient was improved from cholinergic crisis by administration of antidotes. On day 4, she complained of progressive dyspnea and dysphonia after removal of the endotracheal tube. Needle electromyography for neuromuscular confirmation was normal. However, laryngeal electromyography (LEMG) findings were consistent with bilateral laryngeal paralysis suggesting the vagus nerve involvement. Her vocal cord movements were restored to near normal with time and she was discharged on the 20th day after admission. CONCLUSIONS: Physicians should account for the neurotoxic effects of organophosphate poisoning during the first line management of exposed patients. Isolated bilateral vocal cord paralysis (BVCP) should be excluded as a cause, if dysphonia or respiratory distress occurs after extubation in patients with intermediate syndrome. LEMG in such cases can be an important diagnostic adjunct.
