In this contribution I will report on our recent progress in high-speed operation of solution-processed organic field-effect transistors (OFETs) and in realizing fully edible electrolyte-gated organic transistors (EGOTs). Far-field, meters distance communication is possible within the Ultra-High Frequency (UHF) range, e.g. hundreds of MHz – GHz range, which is precluded to OFETs for several long-standing challenges, including resolution in patterning tools, electronic properties of printed materials, contact injection issues and parasitism. Here I will report on our recent progress in addressing such challenges with printed OFETs. Then I will move to discuss the need for edible EGOTs, as a fundamental building block of future edible electronics, which envisions a technology that is safe for ingestion, environmentally friendly, and cost-effective. Edible electronics could potentially target a significant number of biomedical applications, such as remote healthcare monitoring, and of applications for food quality monitoring as well. Here I will report on our investigations on edible and potentially edible semiconductors, and their use in fully edible EGOT architectures.
Printed organic field-effect transistors have been considered for many novel applications towards large area and flexible electronics, since they can enable pervasive integration of electronic functionalities in all sorts of appliances, their portability and wearability. Here I will report on our recent efforts in making printed organic electronics (i) ultrathin, to enhance as much as possible conformability, (ii) fast switching, to enable more applications at Radio-Frequencies and (iii) edible, towards electronics systems made with non-toxic, ingestible materials, serving smart pharmaceuticals and food-tagging applications.
The demand for transparent conductive films (TCFs) is dramatically increasing. In this work tungsten oxide (WO3-x) is studied as a possible option additional to the existed TCFs. We introduce WO3-x thin films fabricated by a non-reactive magnetron RF-sputtering process at room temperature, followed by thermal annealing in dry air. Films are characterized morphologically, structurally, electrically, optically, and dielectrically. Amorphous WO3-x thin films are shown to be n-type conductive while the transparency extends to the near-IR. By evaluating a figure of merit for transparent-conductive performance and comparing to some most-widely used TCFs, WO3-x turns out to outperform in the near-IR optical range
The choice of a staggered or coplanar geometry for organic thin-film transistors (TFT) has significant effects on the static and dynamic electronic properties of the transistors. Using two-port network analysis, we find that the parasitic capacitances and thus the unity current-gain (transit) frequencies are significantly more dependent on the gate-to-source overlap in the staggered TFTs than in coplanar TFTs, and that the transit frequency is higher overall when a coplanar geometry is implemented. We show that these differences are primarily attributed to the lower contact resistance in the coplanar TFTs (10 Ohm-cm) as well as smaller parasitic capacitances associated with the gate-to-contact overlaps.
The develop of Volume Phase Holographic Gratings (VPHGs) working as echelle grating is reported based on binary structures. A mask lithography process was developed to produce the patterns on SU8 photoresist. The binary pattern with 50 l/mm were regular and defect free. The samples were characterized by different duty cycles, which is a key parameter in defining the diffraction efficiency in such binary gratings. The efficiency has been measured at different wavelengths and for different orders. The results have been compared with those obtained by simulations.
The progress in the field of organic photodetectors has recently led to the development of very fast and efficient devices, but their spectral sensitivity is mainly limited to the visible, without covering the regions of the spectrum of greater interest for telecommunications. One of the major issues when dealing with long wavelength organic photodetectors is the usually poor environmental stability of low bandgap organic semiconductors. A possible exception to this scenario is represented by coordination complexes with organic ligands. We employ as photosensitive materials transition metal dithiolene and dioxolene complexes which combine high thermal and photochemical stabilities with high molar extinction coefficients in the near infrared. Taking advantage of the broad tuning of electronic absorption spectra which can be exerted by changing the oxidation state of the complexes, we develop planar metal-semiconductor-metal phostodetectors which are spectrally matched to the optical fiber windows and which can detect light pulses with repetition rates in the range of hundreds of kbit/s.
This investigation demonstrates the existence of organic materials of potential telecom interest and that the detection of infrared light pulses is feasible, thus representing a first step toward organic photodetectors for telecommunications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.