The Critical Choice of PEDOT:PSS Additives for Long Term Stability of Roll‐to‐Roll Processed OPVs

Abstract

The impact of additives mixed with poly(3,4‐ethylenedioxythiophene):polysty­renesulfonate (PEDOT:PSS) on the stability of organic photovoltaic modules is investigated for fully ambient roll‐to‐roll (R2R) processed indium tin oxide free modules. Four different PEDOT:PSS inks from two different suppliers are used. The modules are manufactured directly on barrier foil without a UV filter to accelerate degradation and enable completion of the study in a reasonable time span. The modules are subjected to stability testing following well‐established protocols developed by the international summit on organic photovoltaic stability (ISOS). For the harsh indoor test (ISOS‐L‐3) only a slight difference in stability is observed between the different modules. During both ISOS‐L‐3 and ISOS‐D‐3 one new failure mode is observed as a result of tiny air inclusions in the barrier foil and a R2R method is developed to detect and quantify these. During outdoor operation (ISOS‐O‐1) the use of ethylene glycol (EG) as an additive is found to drastically increase the operational stability of the modules as compared to dimethylsulfoxide (DMSO) and a new failure mode specific to modules with DMSO as the additive is identified. The data are extended in an ongoing experiment where DMSO is used as additive for long‐term outdoor testing in a solar park.

Improving the Operational Stability of PBDTTTz‐4 Polymer Solar Cells Modules by Electrode Modification

“…During ISOS‐L‐2 and ISOS‐L‐3, a new type of degradation mechanism was observed. Bubbles appeared inside the module (Figure left) contrary to a previously reported degradation mechanism where the bubbles formed inside the barrier laminate used for encapsulation . In the case of ISOS‐L‐3, only the carbon modules and the AgNW modules with a silver grid exhibited this phenomena.…”

“…A graphical representation of the architecture of these modules is given in Figure along with a “classical freeOPV” with P3HT:PCBM (Figure left). The silver‐free architecture (Figure center) referred to as Carbon freeOPV has previously been extensively described and studied with P3HT:PCBM as the active layer . The two final architectures, both included in the illustration to the right in Figure , represent the use of a novel front electrode made of silver nanowires (AgNW) and ZnO previously reported by Hösel et al .…”

“…The two final architectures, both included in the illustration to the right in Figure , represent the use of a novel front electrode made of silver nanowires (AgNW) and ZnO previously reported by Hösel et al . and later integrated in R2R manufactured PSCs with P3HT:PCBM as active layer and subjected to stability studies as a function of PEDOT:PSS electrodes . The two AgNW architectures differ in their back electrodes made with either a PEDOT:PSS layer in combination with a silver grid (similar to the first freeOPV generation) or only with a PEDOT:PSS layer.…”

Dependence on material choice of degradation of organic solar cells following exposure to humid air

“…Other research groups have been able to fabricate devices with long operational lifetimes using PEDOT:PSS as the HTL by using additives in the PEDOT:PSS or thorough device encapsulation . The TEM images and results presented in this article highlight why such mitigation is necessary.…”

Efficient hole‐transporting layer MoO3:CuI deposited by co‐evaporation in organic photovoltaic cells

“…However, PEDOT:PSS is problematic since it degrades under UV illumination; it introduces water into the active layer and it is slightly acidic . Therefore, it needs either improvement in the properties of PEDOT, which was successfully done , or use of a different material. In the present paper, we have chosen the second solution, using inorganic materials.…”