Perovskites on plastic!

Recently, solar cells devices based on halide perovskite using a flexible substrate have jumped on the scene. These exciting results have been obtained independently by two different groups. The first paper become from the Energy Research Institute of Singapore. There, they have used ZnO nanorods as scaffold for the MAPbI3 perovskite and they have achieved a conversion effiency of 2.62% on a PET-based substrate[1]. On the other side of the planet, from the Clarendon Laboratory of the University of Oxford, a MAPbI3-xClx cell have been assembled using also PET-based substrate[2]. In this case, the researchers have opted to build the unusual inverted stack placing the p-contact on the conductive substrate. Inverted stack is much harder to harmonize because the perovskite layer is particulary sensitive to any polar solvent used to deposit the following layers like the electron selective layer TiOx, or hole blocking layer like bathocuproine[3]. Anyway, a 6% of efficiency on plastic substrate are good news for these promising photovoltaic active materials.
What is the next? Would there be a tandem cell for the end of 2013?