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Copper nanoparticle inks have drawn much attention since they have the potential to constitute an alternative cost‐effective solution than other noble metals nanoparticle inks such as Ag for indium tin oxide (ITO)‐free printed electronic applications. Our research and development efforts have produced high conductivity copper nanoparticle inks which have excellent jetting and printing properties resulting in high quality inkjet‐printed (IJP) Cu nanoparticle‐based metal grids. We present ITO‐free, Si‐PCPDTBT: PC[70]BM organic photovoltaics (OPVs) processed in ambient low‐cost fabrication conditions comprising for the first time embedded and non embedded inkjet‐printed copper grid/Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the bottom electrode with power conversion efficiencies (PCE) of 2.56 and 3.35%, respectively. The results of the ITO‐free OPVs using inkjet‐printed Cu nanoparticle current collecting grids are discussed relevant to reference ITO‐based OPVs with PCE of 4.92%.

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High power conversion efficiency (PCE) inverted organic photovoltaics (OPVs) usually use thermally evaporated MoO3 as a hole transporting layer (HTL). Despite the high PCE values reported, stability investigations are still limited and the exact degradation mechanisms of inverted OPVs using thermally evaporated MoO3 HTL remain unclear under different environmental stress factors. In this study, we monitor the accelerated lifetime performance under the ISOS-D-2 protocol (heat conditions 65 °C) of nonencapsulated inverted OPVs based on the thiophene-based active layer materials poly(3-hexylthiophene) (P3HT), poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7), and thieno[3,2-b]thiophene-diketopyrrolopyrrole (DPPTTT) blended with [6,6]-phenyl C71-butyric acid methyl ester (PC[70]BM). The presented investigation of degradation mechanisms focus on optimized P3HT:PC[70]BM-based inverted OPVs. Specifically, we present a systematic study on the thermal stability of inverted P3HT:PC[70]BM OPVs using solution-processed poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and evaporated MoO3 HTL. Using a series of measurements and reverse engineering methods, we report that the P3HT:PC[70]BM/MoO3 interface is the main origin of failure of the P3HT:PC[70]BM-based inverted OPVs under intense heat conditions, a trend that is also observed for the other two thiophene-based polymers used in this study.

We report an in-depth investigation of an inkjet-printed silver (Ag) nanoparticle grid combined with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) of different conductivities as an alternative to an indium tin oxide (ITO)-based transparent anode for organic solar cell applications. The reported measurements revealed higher transparency of the inkjet-printed Ag nanoparticle-based grid when compared to different thicknesses of ITO on glass substrates. Based on the proposed current collecting grid, a record power conversion efficiency of 2% is achieved for ITO-free organic solar cells.