Effect of series and shunt resistance on the photovoltaic properties of solution-processed zinc oxide nanowire based CZTS solar cell in superstrate configuration

Here we report the chemical synthesis of a hetero-junction solar cell in superstrate configuration using nanocrystalline p-type Cu2ZnSnS4 (CZTS) as absorber layer, vertically aligned n-type ZnO nanowire array as window layer and very thin ZnS as buffer layer. CZTS thin films comprised of nano-sized grains with pure kesterite phase have been synthesized by simple and cost-effective sol-gel spin coating technique without any post-deposition sulfurization process. ZnS coated vertically aligned ZnO nanowire arrays have been grown by seed-assisted chemical bath deposition technique followed by post deposition chemical sulfurization of nanowire surface. The fabricated solar cell in superstrate configuration, FTO/ZnONW/ZnS/CZTS/Au, has exhibited power conversion efficiency similar to 1.07% with open circuit voltage similar to 0.454 V and short circuit current similar to 5.652 mAcm(-2) when measured in one sun illumination of AM1.5 solar spectrum. The effects of ZnS coating on the photovoltaic properties in association with the series and shunt resistances of the hetero-junction have been studied here.