Page - 127 - in Photovoltaic Materials and Electronic Devices

ofaconductivityof1/5of thebulkconductivityofcopper torepresentamoderate qualityconductive ink[30]. Thespecificcontactresistancewasvariedbetween0.0001 and0.1. ThemodelingwasperformedinComsolandthedataweres furtherprocessed in Matlab. As input, the single diode description of a solar cell with a maximum efficiencyof19%wasusedwith the followingequation: J =A–B*(e´C˚V -1),where J is the current density (A/m2) and V is voltage (V). The constants A, B and C are given in Table 1. In themodel, voltage between 0 and Voc give the curves presented in Figure 2a. The constants are chosen in such a way that the maximum efficiency is19%andthefill factor is80%. Table1alsoshowsthevoltageandcurrentdensity (VmppandImpp, respectively)atwhichthis19%isobtained. Table1. Constantsusedfor the IVcurvesonwhichthemodelingwasbased. Material Voc(V) A B C Vmpp(V) Impp(A/m2) CIGS 0.7 337.5 1.0ˆ10´6 28.1 0.6 318.5 CdTe 0.9 262.7 1.0ˆ10´6 21.55 0.77 248.1 Perovskite 1.1 215.7 1.5ˆ10´6 17.05 0.94 203.3 4. Conclusions Theimpactofthefrontcontactdesignandinterconnectionmaterialoptionswere calculatedfor thinfilmsolarcells. This includesmanyfactorsandvariationof the TCO sheet resistance, scribing area, cell length, finger dimensions, contact resistance and illumination power were assessed. Metallic grids have a benefit in terms of highersolarcell efficiencyandthisalsoenables longercell lengths. However, contact resistancebetweenthemetalandtheTCOmaterialcanreducethisbenefitsomewhat. Author Contributions: Author Contributions: Joop van Deelen contributed to the concept, the modeling, supervised the research work and wrote the manuscript, Yasemin Tezsevinperformedthecontact resistancemeasurements;andMarcoBarinkcontributedto themodeling. Conflictsof Interest: Conflictsof Interest: Theauthorsdeclarenoconflictof interest. References 1. Jeng,M.J.;Chen,Z.Y.;Xiao,Y.L.;Chang,L.B.;Ao, J.;Sun,Y.;Popko,E.; Jacak,W.;Chow,L. ImprovingEfficiencyofMulticrystallineSiliconandCIGSSolarCellsbyIncorporating MetalNanoparticles. Materials2015,8, 6761–6771. 2. Jackson,P.;Hariskos,D.;Wuerz,R.;Kiowski,O.;Bauer,A.;Powalla,M.;Friedlmeier,T.M. Properties of Cu(In,Ga)Se2 Solar Cells with New Record Efficiencies up to 21.7%. Phys.StatusSolidiR2015, 9, 28–31. 3. Green,M.A.;Emery,K.;Hishikawa,Y.;Warta,W.;Dunlop,E.D.Solarcellefficiencytables (version46). Prog.Pothovoltaics. 2015,23, 8025–812. 127