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%.

write technique that requires no masks or lithographic prepatterning of substrates and is compatible with printing manufacturing. Its drop-on-demand (DoD) technology allows the ink droplets to be deposited exactly where required on the substrate, [6] therefore minimizing material loss. Moreover, inkjet printing can be upscaled and transferred to a roll-toroll (R2R) process, [7,8] which can yield a productivity of up to 6 m 2 min −1 , while also producing small feature sizes down to 10 µm and varying shapes. [9][10][11][12] This paves the way to fully solution-processed devices, with all layers including the electrodes being deposited from an ink.The most often used ink formulations can roughly be divided into two categories: inks made from capped metal nanoparticles and metal-organic decomposition inks. [13] To prevent nozzle clogging and comply with printhead restrictions, the inks often contain low metal loading and stabilizers. A treatmentThe fabrication and feasibility of inkjet-printed electrodes for devices such as organic field-effect transistors (OFETs), highly efficient organic photovoltaics (OPVs), and high performance organic light-emitting diodes (OLEDs) underline the versatility of this printing method. [1][2][3][4][5] Inkjet printing is an additive, direct

We report on ITO-free OLEDS with a transparent hybrid Cu nanoparticle grid/PEDOT:PSS electrode processed in ambient conditions. An experimentally based methodology was implemented, where studies on alternative PEDOT:PSS derivatives and Cu grid design were performed, to gradually increase the efficiency of lab scale ITO-free OLEDs. To further increase electrode performance, inkjet-printed (IJP) Cu-grids are embedded to flatten the electrode, reduce leakage current and enhance homogeneity and efficiency. Finally, embedded Cu based ITO-free OLEDs showed current and power efficiencies comparable to reference ITO-based OLEDs. Methods to manufacture large area flat embedded IJP Cu-electrodes on glass and flexible substrates are presented and upscaling prospects of the proposed ITO-free electrode are discussed.

The primary obstacle to the use of lead halide perovskite nanocrystals (NCs) in optoelectronics is the inability of traditional ligand engineering approaches to provide robust surface passivation. The structural lability can be mitigated by employing different ligands such as long-chain quaternary ammonium and zwitterionic surfactants. Here, we report a comprehensive study that probes the impact of such surface passivation routes on the optoelectronic properties of weakly confined CsPbBr 3 NCs. Spectroscopy unravels clear correlations of various photophysical figures of merit with the ligand type used. Compared to NCs decorated by conventional oleic acid/oleylamine ligands, passivation with the quaternary ammonium or zwitterionic surfactants increases the NC solid-state emission yield by up to 40% by halving the average trap depth and increasing by 1.5 times the exciton binding energy. Furthermore, the aforementioned ligands better preserve the size of NCs in thin films, as shown by the absence of significant NC aggregation and the confinement-induced increase by a factor of 2 of the Froḧlich interaction between excitons and optical phonons. The suitability of ligands for photonics is finally assessed by probing metrics, such as the amplified spontaneous emission threshold, the moisture tolerance, and the photoconductivity and electroluminescent performance of lateral and vertical devices, respectively.

Laser-induced forward transfer (LIFT) printing has emerged as a valid digital printing technique capable of transferring and printing a wide range of electronic materials. In this paper, we present for the first time LIFT printing as a method to fabricate silver (Ag) nanoparticle (np) grids for the development of indium tin oxide (ITO)-free inverted PM6:Y6 nonfullerene acceptor organic photovoltaics (OPVs). Limitations of the direct use of LIFT-printed Ag np grids in inverted ITO-free OPVs are addressed through a Ag grid embedding process. The embedded laser-printed Ag grid lines have high electrical conductivity, while the Ag metal grid transparency is varied by altering the number of Ag grid lines within the inverted OPVs’ ITO-free bottom electrode. Following the presented Ag-grid embedding (EMP) process, metal-grid design optimizations, and device engineering methods incorporating an EMB-nine-line Ag np grid/PH500/AI4083/ZnO bottom electrode, we have demonstrated inverted ITO-free OPVs incorporating laser-printed Ag grids with 11.0% power conversion efficiency.