Light-emitting electrochemical cells (LECs) are fabricated by gravure printing. The compromise between device performance and printing quality is correlated to the ink formulation and the printing process. It is shown that the rheological properties of the ink formulations of LECs can be tailored without changing the chemical composition of the material blend.

Organic photodiodes (OPDs) are set to enhance traditional optical detection technologies and open new fields of applications, through the addition of functionalities such as wavelength tunability, mechanical flexibility, light-weight or transparency. This, in combination with printing and coating technology will contribute to the development of cost-effective production methods for optical detection systems. In this review, we compile the current progress in the development of OPDs fabricated with the help of industrial relevant coating and printing techniques. We review their working principle and their figures-of-merit (FOM) highlighting the top device performances through a comparison of material systems and processing approaches. We place particular emphasis in discussing methodologies, processing steps and architectural design that lead to improved FOM. Finally, we survey the current applications of OPDs in which printing technology have enabled technological developments while discussing future trends and needs for improvement.

which makes AJP therefore a suitable candidate for all of the above-mentioned applications.In this work, we present fl exible OPDs fully printed by AJP with equivalent performance to state-of-the-art devices fabricated on rigid substrates by conventional deposition methods. The OPDs exhibit a device transparency of ≈15% while reaching external quantum effi ciency (EQE) values of up to 50%, a high spectral response (SR) (≥0.26 A W −1 ), a specifi c detectivity ( D *) >10 11 Jones from top and bottom illumination, respectively, as well as a bandwidth up to ≈300 kHz at −3 V reverse bias. Furthermore, the devices are exceptionally color neutral and thus very well suited for see through or building-integrated applications.Figure 1 a presents a scheme of the device architectures and energy band diagrams of the two types of printed OPDs fabricated in the so-called inverted confi guration (with the n -contact as the bottom electrode). In this work, two types of OPDs were fabricated. First, OPDs have been deposited via AJP on the top of an ITO covered PET foil (see Figure 1 a(i)). Second, the ITO was replaced by a conductive PEDOT:PSS electrode. The ITOfree device architecture can be seen in Figure 1 a(ii). Aside from the bottom electrode, all devices comprised the same layer stack. In both device confi gurations, a layer of aluminum doped zinc oxide (AZO) nanoparticles was used as the hole-blocking layer for the cathode. The n -doped AZO offers three orders of magnitude higher electrical conductivity compared to intrinsic ZnO, which allows for deposition of thicker layers. [ 11 ] The active layer and the complementary anode consisted of a blended polythieno[3,4b ]-thiopheneco -benzodithiophene (PTB7) and [6,6]-phenyl C71-butyric acid methyl ester (PC70BM) bulk heterojunction and conductive PEDOT:PSS, respectively. Figure 1 b shows photographs of an ITO-free sample containing four fully printed semitransparent OPD pixels fabricated with different active layer thicknesses. The top panel of Figure 1 b exemplifi es the mechanical fl exibility of the OPDs fabricated on fl exible PET substrates, as well as the feasibility to produce a series of devices using the process presented in this work.Printing parameters such as printing speed, material fl ow, and sheath gas fl ow rates were optimized in order to obtain smooth and homogeneous layers suitable for device fabrication. With the optimized printing parameters, the surface modulation, resulting from the sequential printing path, as well as coffee stain effects at the edge of the printed areas were drastically reduced. A detailed explanation of the optimization of the layer deposition is shown in the fi rst section of the Supporting Information ( Figure S1 and Table S1), while the working principle of the AJP can be found elsewhere. [ 12 ] In order to confi rm that the chemical structure of the active materials was Optical sensors have become the focus of great industrial and academic research interest due to their applications in environmental monitoring, [ 1 ] the automotive...

Inkjet printing [13][14][15][16][17] and spray coating processes like Aerosol Jet printing (AJ), [18][19][20][21] enables an exceptional customizability as well as a cost-effective fabrication of devices perfectly matching the individual application requirements.The viability of these processes for the fabrication of entirely printed OPDs has been demonstrated in our work [18] and by others. [22] However, most of the reports so far are limited to single devices. Very recently several groups have started working on the development of processes for the fabrication of multidevice systems paving the way toward the fabrication of fully printed image sensors, micro power modules or displays. [23][24][25][26] However, the device integration and packing density in combination with consistent device performance needed for such systems has remained challenging due to limited registration accuracy, variation in the printing process stability and highly sensitive drying effects. [27,28] Commonly, these challenges are approached from either a mechanical engineering side by improving substrate or print head translations accuracy, printing form and, more recently, by substrate patterning [29,30] or through specific ink formulations that account for substrate's surface energy, viscoelastic properties, or drying-induced instabilities of the layer.In this work, we successfully overcome these challenges by exploiting a recently developed self-alignment process induced to fabricate a fully digitally printed image sensor based on organic photoactive materials with high performance, reproducibility, and lab-scale fabrication yields of 100%. The passive matrix image detector is composed of 256 micropixels with individual active areas of ≈250 µm × 300 µm for a total footprint of 64 mm 2 . To the best of our knowledge, this is the highest packing density and number of functional pixel among the reported systems not making use of evaporation techniques or a TFT-backplane. Characterization of the single OPD pixels demonstrated state-of-the art performances with spectral responsivities (SR) of up to 0.3 A W −1 , a linear dynamic range (LDR) of 114 dB and calculated specific detectivities (D*) > 10 12 Jones, thereby competing with performances of current inorganic photodetector devices. Figure 1a illustrates the OPD fabrication process. The bottom electrodes where deposited via a self-aligning process where AJ printed SU-8 lines (step I) served as dewetting structures for the inkjet printed Ag ink (step II). The dewetting process of the functional ink on SU-8 is driven by the low Here, an entirely printed passive matrix image detector composed of 256 individual pixels with an individual active area of ≈250 µm × 300 µm is fabricated. The fabrication of the organic photodetector (OPD) array is enabled by exploiting a self-alignment process of the functional layers induced by digitally printed dewetting patterns resulting in high-performance reproducibility and fabrication yields of 100%. The single OPD pixels fabricated under ambient condition...

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