Abstract: Organic photovoltaic cells (OPVs) have already reached remarkable power conversion efficiencies (PCE), however, intrinsic photodegradation of the active layer often leads to dramatic drops in device performance. Luminescence down-shifting (LDS) coatings absorbing in the UV can be used in OPVs to simultaneously filter UV light and re-emit it with lower energy, in a region matching the maximum spectral response of the cells. Such strategy can increase the net photocurrent generated by the cell while protecting it from high energy (UV) photons. In this work [1], we investigate a hybrid LDS layer, composed of a fluorescent complex, Eu(tta)3.2H2O, dispersed in an organic-inorganic silicon-based matrix, as a coat on organic solar cells based on the PTB7-Th:ITIC bulk heterojunction. The optical properties of the LDS coating and the optimal conditions to deposit it over the OPV devices are described. It was found that the LDS coat performs mainly as a protecting UV-filter and that PCE of the cells can be raised in 22 %.

[1] J. Farinhas, S. F. H. Correia, L. Fu, A. M. P. Botas, P. S. André, R. A. S. Ferreira, A. Charas, Frontiers in Nanotechnology, April 2021, Vol 3, Article 635929.

Acknowledgments: CICECO-Aveiro Institute of Materials (UIDB/50011/2020&UIDP/50011/2020), Instituto de Telecomunicações (UIDB/50008/2020-UIDP/50008/2020), projects Solar-Flex (CENTRO-01–0145-FEDER-030186), SusPhotoSolutions (CENTRO-01–0145-FEDER-000005), and Suprasol (PTDC/QUI-QOR/28365/2017) financed by FCT/MEC – Portugal.