Additive color mixing of semitransparent laminated tandem type polymer light-emitting diodes

Abstract

Polymer light-emitting diodes (PLEDs) are generally fabricated using the wet process. Although it is difficult to stack multiple layers by the wet process, it is compatible with the lamination process that can be used to fabricate multi-layer tandem type devices. We fabricate tandem type PLEDs composed of two transparent substrates using the lamination process. Stacked red and green PLEDs exhibit additive color mixed emission resulting in orange emission. By careful selection of materials, similar emission is observed from both substrates of the semi-transparent tandem PLEDs because the over-layer does not absorb the emission from the under-layer.

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

“…Notably, compared to the evaporated Ag thin films composed of Ag atoms, the inkjet-printed Ag films converted from the Ag ink were composed of various additives and chemicals that interacted with each other, which could minimize Ag diffusion during heat treatment [42]. Moreover, as heat treatment in lamination has already been reported to improve the contact between the cathode and organic semiconductor layers [43][44][45][46][47][48][49], heat treatment after the lamination process could enhance electron injection, allowing significant turnon voltage reduction and efficiency improvement in LIP-PLEDs. However, as the heat treatment forms more intimate contact, the inkjet-printed Ag electrodes were partially transferred to the base substrate, or the bus lines were transferred vice versa when the cover substrate was peeled off from the base substrate (supplementary figure 10 and supplementary video 2).…”