Role of Polymeric Metal Nucleation Inducers in Fabricating Large‐Area, Flexible, and Transparent Electrodes for Printable Electronics

Abstract

The advent of special types of transparent electrodes, known as "ultrathin metal electrodes," opens a new avenue for flexible and printable electronics based on their excellent optical transparency in the visible range while maintaining their intrinsic high electrical conductivity and mechanical flexibility. In this new electrode architecture, introducing metal nucleation inducers (MNIs) on flexible plastic substrates is a key concept to form high-quality ultrathin metal films (thickness ≈ 10 nm) with smooth and continuous morphology. Herein, this paper explores the role of "polymeric" MNIs in fabricating ultrathin metal films by employing various polymers with different surface energies and functional groups. Moreover, a scalable approach is demonstrated using the ionic self-assembly on typical plastic substrates, yielding large-area electrodes (21 × 29.7 cm 2 ) with high optical transmittance (>95%), low sheet resistance (<10 Ω sq −1 ), and extreme mechanical flexibility. The results demonstrate that this new class of flexible and transparent electrodes enables the fabrication of efficient polymer light-emitting diodes.

Supersmooth Ta2O5/Ag/Polyetherimide Film as the Rear Transparent Electrode for High Performance Semitransparent Perovskite Solar Cells

“…The pink layer denotes the CBL composed of ZrAcac, PEI, or ZrAcac/PEI (Figure b), which was spin‐coated on the underlying PCBM film using the optimal concentration of ZrAcac (1 mg mL −1 ) and PEI (0.1 mg mL −1 ) solutions with isopropanol (IPA) as solvent . The main motivation for the use of PEI is that this polymer molecule acts as a good substrate for deposition of smooth silver films . The function of CBL at the cathode interface is clearly demonstrated in the current density–bias voltage ( J–V ) curves in reverse scan of the devices tested under a simulated AM1.5G sunlight (100 mW cm −2 ) (Figure c).…”

“…The silver grains in both kinds of films are well connected with each other (Figure f,h), which contribute to the high conductivity and transmittance shown in Figure a,c. Different from PCBM and ZrAcac, the abundant amine groups in the backbone of PEI molecules are inclined to uniformly localize Ag adatoms by the AgN bonds and hence to offer the low energy nucleation sites for the growth of continuous silver films …”

Embedded-grid silver transparent electrodes fabricated by selective metal condensation

“…1c(i) and (ii)), or PET modified with an ultra-thin layer of PEI (polyethylenimine) the latter of which is known to serve as an effective seed layer for evaporated Ag film. 16 The substrate was then exposed to Ag vapour in a vacuum evaporator until a total thickness of 90 nm was deposited onto PFDMA-free regions and the adjacent quartz crystal microbalance ( Fig. 1c(iii)).…”

Metal-Enhanced Adsorption of High-Density Polyelectrolyte Nucleation-Inducing Seed Layer for Highly Conductive Transparent Ultrathin Metal Films

“…This is because the structures of Ag films so deposited are still far from being ideal and consist of rough surfaces with high densities of voids and grain boundaries when the film thickness is < 6 nm. Recently, it was demonstrated that the density of the sites that are chemically reactive with the evaporated Ag atoms could be determined by the concentration of functional amine groups on the NISL surface (Jeong et al, 2017). However, the adsorbed amine groups in the PEI NISL is always limited by the poor electrostatic attraction to the weakly charged substrate as well as the strong repulsion between the PEI chain entanglements (Hoogeveen et al, 1996;Li et al, 1997;Dobrynin et al, 2000).…”