Printed transistors on paper: Towards smart consumer product packaging

The integration of fully printed transistors on low cost paper substrates compatible with roll-to-roll processes is demonstrated here. Printed electronics promises to enable a range of technologies on paper including printed sensors, RF tags, and displays. However, progress has been slow due to the paper roughness and ink absorption. This is solved here by employing gravure printing to print local smoothing pads that also act as an absorption barrier. This innovative local smoothing process retains desirable paper properties such as foldability, breathability, and biodegradability outside of electronically active areas. Atomic force microscopy measurements show significant improvements in roughness. The polymer ink and printing parameters are optimized to minimize ink absorption and printing artifacts when printing the smoothing layer. Organic thin film transistors (OTFT) are fabricated on top of this locally smoothed paper. OTFTs exhibit performance on par with previously reported printed transistors on plastic utilizing the same materials system (pBTTT semiconductor, poly-4-vinylphenol dielectric). OTFTs deliver saturation mobility approaching 0.1 cm²V^-1s^-1 and on-off-ratio of 3.2 × 10⁴. This attests to the quality of the local smoothing, and points to a promising path for realizing electronics on paper. Fully printed transistors are demonstrated on paper substrates with performance on par with plastic based devices. Desirable paper properties such as foldability, breathability, and biodegradability are preserved outside of electronically active areas by an innovative locally printed smoothing process. This process is fully compatible with existing paper packaging process flows.