Enhancement of inverted polymer solar cells with solution-processed ZnO-TiOx composite as cathode buffer layer

Solution-processed zinc oxide (ZnO) nanocrystal modified with titanium oxide (TiOx) precursor is introduced as cathode interfacial layer in inverted bulk-heterojunction polymer solar cells. The resultant inverted polymer solar cell exhibits an open-circuit voltage of 0.87 V, a fill factor of 0.67, and an overall power conversion efficiency of 6.53%, respectively, higher than those of the control cells with sole ZnO or TiOX as the cathode interfacial layers. Further studies verify that the improved morphology and electronic structure of ZnO-TiOX composite layer favors reducing shunt loss and interfacial charge recombination and hence enhancing the photovoltaic performance. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4722800]