Ageing evaluation of different polymeric Er3+ downshifters exposed to harsh outdoor conditions

In this work a comparison of the ageing of [Eu(bathphen)(tta)3]/PMMA and [Eu(pyphen)(tta3)/PMMA downshifters placed on top of solar panels in the field is reported. The solar panels have been placed in Tenerife, Canary Island, and exposed to harsh outdoor conditions. The downshifters have been covered by a low iron glass to simulate the encapsulation. The results reveal an improvement of the total power of the solar panels with downshifters in comparison with a reference panel. Moreover, [Eu(bathphen)(tta)3]/PMMA, shows no evidence of degradation after 3 weeks exposed to the ambient conditions. A climatic chamber has been also used to accelerate the degradation process, showing that the UV dose on the DS layer is directly related to the degradation of the down-shifting properties of this layer.