Seite - 184 - in Photovoltaic Materials and Electronic Devices

3.4. SolarCellCharacterization The nanoparticle-coated and uncoated solar cells have been analyzed using a designed I–V characterization setup. The irradiance generated from a Xenon lamp (Oriel100W,Irvine,CA,USA)followedbyairmass (NewportAM1.5G, Irvine,CA, USA) is exposed to the coated/uncoated solar cells. Then, the different values of I and V are measured using Source meter 2400-C source meter (Keithley, Cleveland, OH, USA), with sweeping parameters as voltage range from´1 to +1 V through 1000measuringpointswith50msstoppagetimeperreading. Throughtheextracted I-values corresponding to the swept V-values, both I–V and P–V curves are drawn. FromtheI–Vcurve, someparameterscouldbemeasuredsuchasfillingfactor,Vo.c, Is.c and the optical efficiency. Using COMSOL Multiphysics software (COMSOL Inc., Burlington, MA, USA), generation rate and E-field distribution are analyzed withandwithout thenanoparticle layeronsiliconsolarcell. 4. Conclusions This paper introduces a novel study of using reduced erbium-doped ceria nanoparticles (REDC NPs) as a coating layer on silicon solar cells. The presented work shows full optical characterization of the synthesized nanoparticles. The experimentalresultsshowthevisiblefluorescenceemittedunderbothexcitationsof NIR and near UV. In addition, the results of the band gap and fluorescence confirm theformationofCe3+ trapstateswhichareassociatedwiththeformationofcharged oxygen vacancies. That could increase the conductivity for any photo-generated electrons in the host NPs. When depositing REDC NPs on the back sides of solar cells, a promising improvement in the solar cell efficiency has been observed from 15% to 16.5% due to the mutual impact of improved electric conductivity and multi-optical conversions. In addition, the generation rate and maximum electric fields formedinthesolarcellshavebeenslightly improveddueto thecoating. Acknowledgments: This work was funded in part by a NSF STTR Phase I grant with MW Photonics (award 0930364). Also, some the authors are supported through Virginia Tech MiddleEastandNorthAfrica (VT-MENA)programandcenterofSmartCIresearchcenter in Alexandria University. The authors appreciate the support of both Ibrahim Hassounah and Michael Ellis’ lab in ICTAS, Virginia Polytechnic Institute State University (Virginia Tech), in the process of annealing the synthesized nanoparticles. Also, the authors appreciate the support of Don Leber; manager of the Micron Technology Semiconductor Processing LaboratoryatVirginiaTech. AuthorContributions: NaderShehatawasresponsible forpreparationandcharacterization of the nanoparticles. Michael Clavel was responsible for coating procedure and solar cell experimentalsetupunderthesupervisionofbothNaderShehataandKathleenMeehan. Effat SamirwasthemainpersonforsolarcellanalysisunderthesupervisionofMohammedSalah. SohaGaballahdidtheTEMimageof thenanoparticles. Conflictsof Interest: Theauthorsdeclarenoconflictof interest. 184