Solution processing manufacturing is the key method to reduce the OLED device production cost. Furthermore, digital printing techniques such as inkjet printing provide the advantages of mask-free patterning, non-contact manufacturing and direct chip-integration. However, a complex layer structure consisting of ultrathin layers is typically required to obtain high device performance, which is difficult for inkjet printing manufacturing due to interlayer mixing, limited layer uniformity, and limited material availability. In this contribution, we introduce an ITO-free, inkjet-printed transparent OLED with a simple 4-layer structure via an inkjet-printable Al:ZnO:PEI interlayer. This is the first ITO-free, vacuum-free, fully solution-processed transparent OLED using the inkjet printing technique as the exclusive technique for electrode deposition and patterning. High emission brightnesses of 50 000 cd m⁻² and 16 000 cd m⁻² were achieved in a voltage-pulsed driving mode on ITO and silver nanowire embedded PEDOT:PSS bottom electrodes, respectively. In order to use the OLEDs for on-chip fluorescence sensing applications, the operational lifetime was also tested under a high emission brightness of ∼10 000 cd m⁻². LT85 was achieved after 3000 pulses.

We report the first fluorescence light detector combining a fully solution processed organic electrochemical cell (OLEC) and a fully solution processed organic photodiode (OPD) within one microfluidic chip. The blue OLEC was used as the excitation source, whereas the OPD was used for detection of the emitted fluorescent light. Two orthogonally oriented linear polarizers were used as excitation and emission filters, enabling the use of fluorescent dyes with emission and absorption peaks very close to each other. In addition the system is compatible with many different fluorescent dyes. The filters and organic devices were mounted onto a microfluidic glass chip. Fluorescein amidite (FAM) was used as a model dye to characterize and demonstrate the concept of the system. Despite a very close excitation peak (492 nm) and emission peak (518 nm) of FAM, we were able to detect FAM concentrations as low as 1 μM even for a brightness value of the OLEC as low as 500 cd m⁻². This opens the possibility of producing low cost, portable and disposable fluorescence sensors with a high sensitivity.

Organic light emitting diodes (OLEDs) have the advantages of self-emitting property, high luminous efficiency, full-colour capability, wide viewing angle, high contrast, low power consumption, low weight and flexibility. All these capacitate OLEDs to be an attractive optical source for display and lighting applications. However, the current manufacturing cost is still relative high, which obstacle its success in the display and lighting market. The main problems are indispensable low work function material for cathode and/or electron injection layer such as Ba, LiF, which require vacuum deposition and/or inert fabrication atmosphere, and widely used anode ITO which are not solution processable. Therefore, the fully solution processing manufacturing techniques are under intense investigation in order to reduce the cost. Compared to OLEDs, its derivation, organic light-emitting electrochemical cells (OLECs), show an intrinsic advantage in fully solution processing. By mixing metal ions and a solid electrolyte with light-emitting polymers as active materials, an in-situ doping and in-situ PN-junction can be generated within a three layer sandwich device. Because of this doping effect, work function adaption is not necessary and air-stable flexible electrodes like PEDOT:PSS can be used. Hereby, a manufacturing process for fully solution-processed transparent OLECs is presented, which consist of inkjet printed PEDOT:PSS anode and cathode, spin-coated ZnO interlayer, and spin-coated yellow light-emitting polymer plus dopant. Inkjet printing the electrode give the advantages of mask-free and spin-coating provides the homogeneous active layers. Furthermore, by manufacturing on 70 μm thin glass, a relative flexible transparent light source can be realized and enable the potential emerging applications like signal display on textiles

Additive manufacturing (AM), so‐called 3D printing, has reshaped manufacturing technologies with attractive alternatives to the traditional centralized, subtractive‐based mass production. Further functionalities like multimaterial AM (MMAM) are essential for mainstream manufacturing. With MMAM of electrical traces, the traditional printed circuit board can be transformed to freeform 3D electronics using the entire volumetric space. Although research groups attempt MMAM for freeform 3D electronics, achieving easy integration of the electrical traces with high conductance into dielectric substrates in a streamlined and simplified process remains challenging. Herein, an in‐house developed printer, named Synkròtima, is demonstrated for one‐stop printing of 3D dielectric parts with fully embedded and structured conductive features via drop‐on‐demand printing of molten metal for the first time. Printed traces show 12 times lower electrical resistance of at 230 μm linewidth than the lines from conductive inks. Printed traces with 100 μm dot spacing reveal exemplary shape fidelity with a standard deviation of only 7 μm. Quantitative estimation of adhesion of metal traces to dielectric reveals a mean shear‐off force of 7.20 N which is half of what is obtained for reflow soldered electronics. Demonstrators with embedded functional electrical circuits, directly interconnected components, and 3D out‐of‐plane metal structures are printed via Synkròtima.