Temporary Tattoo Approach for a Transferable Printed Organic Photodiode

Generation of ultrathin, transferable, and imperceptible electronic devices [e.g., organic photodiode (OPD)] for multiple applications, such as personalized health monitors and wearables, is emerging due to the continuous development of materials and manufacturing processes. For such devices, the choice of a suitable substrate is of utmost importance. A water decal transfer from a temporary tattoo paper is adopted here as a substrate for ultrathin and conformable organic components because of easy and reliable transfer of a ≈600 nm robust and transparent polymer nanofilm of ethyl cellulose. Strategies for the fabrication of a transferable OPD on a temporary tattoo are investigated. A device with an overall thickness <1 μm and its performance after transfer are demonstrated. Then, efforts are put into fabricating an OPD by inkjet printing with a water-soluble active layer consisting of polythiophene and fullerene derivatives to aid cost- and material-efficient, large-scale production possibilities. Additionally, a second semitransparent electrode made of printed aluminum-doped zinc oxide and silver nanowires is used to allow usage from both sides to enhance the application potential. Both OPD examples presented here need improvement of the device performance but permitted us to highlight the versatility and application potential of temporary tattoos for transferable components. Target surfaces for the final application after transfer include artificial (flat and smooth, e.g., glass, or even complex and rough, e.g., concrete, paper, and so forth) as well as natural ones.