Silver Mesh Electrodes via Electroless Deposition-Coupled Inkjet-Printing Mask Technology for Flexible Polymer Solar Cells

The application of metal grids as flexible transparent electrodes (FTEs) in optoelectronic devices is significantly influenced by poor adhesion and thickness difference between the metal and the substrate, resistance distribution uniformity, and a high annealing temperature. Direct inkjet printing of the metal mesh can overcome junction resistance while maintaining high conductivity, but the metal mesh thickness is still unsatisfactory. In addition, inkjet printing of mechanically durable metal FTEs directly on flexible substrates is challenging because of the high-temperature sintering treatment. Electroless deposition is a well-established method for low-cost and large-scale deposition of metal films. Here, ultrathin and ultraflexible Ag mesh@polydopamine (PDA)/poly(ethylene terephthalate) (PET) FTEs were fabricated by integrating inkjet-printed polymer matrices on a PDA-modified flexible PET substrate to form consecutive patterns as a mask and performing subsequent electroless deposition of the Ag mesh. The FTEs exhibit an excellent sheet resistance (Rs) of 9 Ω/sq with 89.9% transmittance. The resultant polymer solar cells show a superior power conversion efficiency (PCE) of 10.24% with 1 cm2 area and feature excellent flexural endurance (81% of initial PCE after 1500 bending cycles) and operational reliability (83% of initial PCE after 30 days). This ecofriendly and large-area fabrication technique has potential for future commercial applications of wearable electronics.