Identification of Degradation Mechanisms in Slot-Die-Coated Nonfullerene ITO-Free Organic Solar Cells Using Different Illumination Spectra
In this work, we have studied degradation mechanisms of nonfullerene-based organic solar cells with PET/Ag/ZnO/PBDTB-T:ITIC/PEDOT:PSS/CPP PEDOT:PSS device structure. We compare pristine and degraded samples that were subjected to outdoor degradation following the standard ISOS-O2 protocol. The ideality factors for different incident wavelengths obtained from open-circuit voltage vs irradiation level and current density–voltage (J–V) measurements at different temperatures indicate that for aged samples recombination is governed by the Shockley–Read–Hall mechanism occurring in a region near the anode. Samples were also characterized using impedance spectroscopy (IS) and fitted to an electrical model. Impedance parameters were used to obtain mobility, indicating a clear degradation of the active layer blend for aged samples. The change in the chemical capacitance also reveals a worsening in carrier extraction. Finally, two-dimensional (2D) numerical simulations and fits to experimental J–V curves confirm the existence of a layer near the anode contact with poorer mobility and a decrease in the anode work function (WF) for the degraded samples. ; This work was supported by Comunidad de Madrid under the SINFOTON2-CM Research Program (S2018/NMT-4326-SINFOTON2-CM) and the Spanish Ministry of Economy, the Agencia Estatal de Investigación, and European Union's FEDER under the TEC2016−77242-C1/C2/C3 AEI/FEDER, UE Projects. The work of E.L.-F. was supported by the Ministerio de Educación y Formación Profesional for his Doctoral Grant through the FPU Research Fellowship under Grant FPU17/00612. M.M., J.L., E.D., and V.T. acknowledge that part of this work was developed within the RollFlex project, part-financed by Interreg Deutschland-Danmark with means from the European Regional Development Fund and the Southern Denmark Growth Forum. M.M. and V.T. acknowledge the support from the Villum Foundation for Project CompliantPV (Grant No. 13365). Finally, all authors acknowledge the support from the EU Framework Program Horizon ...
