Lamination of inkjet-printed Ag electrodes for highly patternable and customizable polymer light-emitting diodes

Abstract

Inkjet printing that ensures superior patternability and customizability can be fully exploited as top electrodes in thin-film-based light-emitting devices. However, direct inkjet printing onto multi-layered thin films severely damages the underlying functional layers due to intermixing with the ink solvents, resulting in poor device efficiencies. Here, we report a lamination of inkjet-printed Ag electrodes as a top cathode for polymer light-emitting diodes (PLEDs). The organometallic Ag ink was printed on surface-modified elastomers with stable wettability, and drop spacing was further optimized for low surface roughness. The lamination of Ag cathodes establishes intimate contact between the electrodes and the functional layers, allowing light emission of PLEDs along the printed patterns. Furthermore, additional heat treatment improves the electron injection, resulting in a reduction of turn-on voltage and higher current/power efficiencies. To illustrate the practicability of our laminated PLEDs, we demonstrate passive-matrix driven PLEDs with all-inkjet-printed electrodes by laminating the top cathode arrays crossing the bottom inkjet-printed anodes.