Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 112: Energy materials: CIGS and related photovoltaics
HL 112.1: Talk
Friday, April 4, 2014, 09:30–09:45, POT 112
Depleted heterojunction solar cells with CuInS2 and ZnO nanocrystals - optical modeling and electrical characterization — •Dorothea Scheunemann, Sebastian Wilken, Jan Keller, Michael Richter, Ingo Riedel, Holger Borchert, and Jürgen Parisi — University of Oldenburg, Department of Physics, Energy and Semiconductor Research Laboratory, 26111 Oldenburg
Colloidal quantum dot (CQD) solar cells with solution-producible absorber layers have made rapid progress in the last few years. In particular, the so-called depleted heterojunction concept, consisting of a wide band gap n-type semiconductor and a p-type CQD film as absorber, appears promising. Here, we study the potential of CuInS2 nanocrystals (NCs) as a relevant alternative to the toxic Pb or Cd compounds for usage in depleted heterojunction solar cells. Two different layer stacks, based on a bilayer heterojunction between CIS and ZnO NCs, were investigated by means of high resolution electron microscopy and optical modelling. We applied variable-angle spectroscopic ellipsometry to derive the optical constants of the involved layers. These data served as input parameters into optical simulations in order to estimate light absorption in the individual layers of the device stack with the transfer matrix formalism. Here, we present the simulated data in comparison with experimental results. Furthermore, we studied the dependence of the current-voltage characteristics, as well as the external quantum efficiency on illumination conditions, i.e., the presence of UV light.