5 research outputs found
AerosolâJetâPrinted DonorâBlocking Layer for Organic Photodiodes
Organic photodiodes (OPDs) are optical sensors combining high performance, lightweight mechanical flexibility, and processability from solution. Their fabrication by industrial printing techniques opens a wide range of innovative applications for emerging fields in sensing and the Internet of Things. They typically consist of printed multilayers with functionalities to absorb light, to extract charges, or to reduce detection noise. However, the printing of such device architecture poses a challenge as the deposition of a material can lead to disruption of film morphology or intermixing of materials if its solvent interacts with the previously deposited layer. This work proposes a process to print multilayers from the same solvent system utilizing the aerosol-jet technique. By fine adjustment of the aerosol properties through the tube temperature (TTube), the drying time of poly(3-hexylthiophene-2,5-diyl) (P3HT) printed layers is significantly reduced. This allows its deposition onto a P3HT-based bulk-heterojunction (BHJ) without negatively affecting its performance. The additional printed P3HT layer, spatially extends the donor region of the BHJ, providing ideal hole extraction and simultaneous noise reduction by the blocking of injected electrons. This donor blocking layer (DBL) yields a noise reduction of two orders of magnitude in OPDs operated under â2 V reverse bias
AerosolâJetâPrinted DonorâBlocking Layer for Organic Photodiodes
Organic photodiodes (OPDs) are optical sensors combining high performance, lightweight mechanical flexibility, and processability from solution. Their fabrication by industrial printing techniques opens a wide range of innovative applications for emerging fields in sensing and the Internet of Things. They typically consist of printed multilayers with functionalities to absorb light, to extract charges, or to reduce detection noise. However, the printing of such device architecture poses a challenge as the deposition of a material can lead to disruption of film morphology or intermixing of materials if its solvent interacts with the previously deposited layer. This work proposes a process to print multilayers from the same solvent system utilizing the aerosol-jet technique. By fine adjustment of the aerosol properties through the tube temperature (TTube), the drying time of poly(3-hexylthiophene-2,5-diyl) (P3HT) printed layers is significantly reduced. This allows its deposition onto a P3HT-based bulk-heterojunction (BHJ) without negatively affecting its performance. The additional printed P3HT layer, spatially extends the donor region of the BHJ, providing ideal hole extraction and simultaneous noise reduction by the blocking of injected electrons. This donor blocking layer (DBL) yields a noise reduction of two orders of magnitude in OPDs operated under â2 V reverse bias
Substrate-Independent Surface Energy Tuning via Siloxane Treatment for Printed Electronics
Digital printing
enables solution processing of functional materials
and opens a new route to fabricate low-cost electronic devices. One
crucial parameter that affects the wettability of inks for all printing
techniques is the surface free energy (SFE) of the substrate. Siloxanes,
with their huge variety of side chains and their ability to form self-assembled
monolayers, offer exhaustive control of the substrate SFE from hydrophilic
to hydrophobic. Thus, siloxane treatment is a suitable approach to
adjust the substrate conditions to the desired ink, instead of optimizing
the ink to an arbitrary substrate. In this work, the influence of
different fluorinated and nonfluorinated siloxanes on the SFE of different
substrates, such as polymers, glasses, and metals, are examined. By
mixing several siloxanes, we demonstrate the fine tuning of the surface
energy. The polar and dispersive components of the SFE are determined
by the OwensâWendtâRabelâKaelble (OWRK) method.
Furthermore, the impact of the siloxanes and therefore the SFE on
the pinning of droplets and wet films are assessed via dynamic contact
angle measurements. SFE-optimized substrates enable tailoring the
resolution of inkjet printed silver structures. A nanoparticulate
silver ink was used for printing single drops, lines, and source-drain
electrodes for transistors. These were examined in terms of diameter,
edge quality, and functionality. We show that by adjusting the SFE
of an arbitrary substrate, the printed resolution is substantially
increased by minimizing the printed drop size by up to 70%