A 13.56 MHz Rectifier Based on Fully Inkjet Printed Organic Diodes.

The increasing diffusion of portable and wearable technologies results in a growing interest in electronic devices having features such as flexibility, lightness-in-weight, transparency, and wireless operation. Organic electronics is proposed as a potential candidate to fulfill such needs, in particular targeting pervasive radio-frequency (RF) applications. Still, limitations in terms of device performances at RF, particularly severe when large-area and scalable fabrication techniques are employed, have largely precluded the achievement of such an appealing scenario. In this work, the rectification of an electromagnetic wave at 13.56 MHz with a fully inkjet printed polymer diode is demonstrated. The rectifier, a key enabling component of future pervasive wireless systems, is fabricated through scalable large-area methods on plastic. To provide a proof-of-principle demonstration of its future applicability, its adoption in powering a printed integrated polymer circuit is presented. The possibility of harvesting electrical power from RF waves and delivering it to a cheap flexible substrate through a simple printed circuitry paves the way to a plethora of appealing distributed electronic applications.

Reproducible, High Performance Fully Printed Photodiodes on Flexible Substrates through the Use of a Polyethylenimine Interlayer.

This paper investigates with a statistical analysis the issue of performance reproducibility and optimization in fully inkjet-printed organic photodetectors on flexible substrates. The most crucial process step to obtain reproducible, well performing devices with a high process yield turns out to be the printing of the thin polyethylenimine interlayer used as a surface modifier for the bottom electrode. Controlling solution composition and deposition parameters for this layer, a 57 nA cm-2 mean reverse dark current was achieved, with an outstanding standard deviation as low as 15 nA cm-2, with dramatic improvements in process yield (from less than 20% to over 90%). Device performance in terms of dark currents, EQE (from 50% up to 90% at 525 nm, depending on process), and rectification (ratio between forward current and reverse current over 104 and reaching 105 in the best cases) is among the best for fully printed detectors. Furthermore, the importance of relative humidity control in the deposition environment during the interlayer printing on device characteristics is reported, indicating the processing conditions optimal for scaling to mass manufacturing. The overall interlayer optimization approach was applied to a process using widely adopted materials in the organic optoelectronics field, and thus retains relevance on a broad range.