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Organic photovoltaic (OPV) devices have shown remarkable performance progress in recent years, reaching current record power conversion efficiency (PCE) values of 16.4% for single junction and 17.3% for multi junction devices, owing mostly to the impressive developments made within synthesis of new non-fullerene acceptors. This progress places organic solar cells at the forefront of thin-film photovoltaic technology. However, in order to meet industrial demands and reach high performance values in industrial settings, further research and development efforts within Roll-to-Roll (R2R) and Sheet-to-Sheet (S2S) processing of OPV devices under ambient conditions are required. Furthermore, OPV modules being manufactured through such up-scaled processing techniques should ideally be developed from low cost materials, and show good stability towards various different operational stress conditions. In this work, we demonstrate combined R2R and S2S development of ITO-free OPV devices, which are based on the non-fullerene material system PBDB-T:ITIC. The 2 devices are processed from R2R vacuum sputtering and S2S slot-die coating at ambient conditions, and reach cell PCE values of 5.5%. In addition, we introduce a correlation between different barrier films, both commercial and sputtered inorganic coatings on ultra-clean PET, and the lifetime of the developed devices. The results therefore demonstrate an important step in the development of OPV devices from R2R and S2S processes in industrial settings.

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markets for the more mature technologies, and research for the emerging technologies, are increasing year by year. Among these are organic, metal oxide, and organo-hybrid perovskite semiconductor transistor, light-emitting diode, and solar cell-based systems. [1][2][3][4] Large-area optoelectronics is developed on rigid (mainly on glass) and flexible (mainly on plastic such as polyethylene terephthalate, PET) substrates [5] with other types of substrates also being investigated such as paper, [6,7] flexible glass, [8] or textiles. [9] Organic lightemitting diodes (OLEDs), for example, are today one of the most commercialized technologies especially in small-display markets (e.g., smartphone displays) where they now take a major share of the market. In research laboratories, perovskite solar cells (PSC) have seen a huge interest reaching certified record efficiencies of 25.2% at standard test conditions (Air mass AM1.5G, 1000 W m −2 , 25 °C) [10] within only 10 years of development. Further they reach the highest power output densities under artificial indoor illumination (i.e., 20.2 µW cm −2 at 200 lx [11] ) which make them not only a bright candidate for energy harvesting outdoors but also for indoor IoT devices, sensors, and small consumer electronics [12] even for flexible substrates under artificial lighting. [13,14] The success of large area electronics in general lies in the advantageous properties of the materials used and in the fabrication processes (e.g., evaporation, sputtering or solution processing via printing techniques). These are also often compatible with flexible substrates. [15,16] Nevertheless, lifetimes of many of the constituent materials suffer when coming in contact with ambient moisture and oxygen [17][18][19] which can induce chemical degradation to the semiconducting, transport, and electrode layers. [20][21][22] To avoid moisture and oxygen ingress and further degradation, devices must be encapsulated with permeation barriers ensuring a water vapor transmission rate (WVTR) range of 10 −3 to 10 −6 g m −2 d −1 [23][24][25][26][27][28] and an oxygen transmission rate (OTR) between 10 −2 and 10 −5 cm 3 m −2 d −1 . [29][30][31][32] Encapsulation Effective transparent barrier/encapsulation systems represent a key enabling technology for large-area electronics. Securing stability to the environment is vital. Here, the effects of architectures, application processes, and water vapor transmission rates (WVTR) of transparent flexible ultra-high permeation barrier films (UHPBF) applied to substrates with adhesive resins are unraveled for attaining long lifetime, and compared with polyethylene terephthalate and glass barriers. How strongly performance of barrier/adhesive systems depends on barrier orientation, adhesion, manipulation, defects, and storage procedures is quantified via calcium tests. Furthermore, it is found that introducing an additional adhesion-promoting layer on the standard UHPBF stack reduces WVTRs by a factor of 5 compared to barriers without it. Finally, barriers are used fo...

Electroluminescent devices become warm during operation, and their performance can, therefore, be severely limited at high drive current density. Herein, the effects of this self‐heating on the operation of a light‐emitting electrochemical cell (LEC) are systematically studied. A drive current density of 50 mA cm−2 can result in a local device temperature for a free‐standing LEC that exceeds 50 °C within a short period of operation, which in turn induces premature device degradation as manifested in the rapidly decreasing luminance and increasing voltage. Furthermore, this undesired self‐heating for a free‐standing thin‐film LEC can be suppressed by the employment of a device architecture featuring high thermal conductance and a small emission‐area fill factor, since the corresponding improved heat conduction to the nonemissive regions facilitates more efficient heat transfer to the ambient surroundings. In addition, the reported differences in performance between small‐area and large‐area LECs as well as between flexible‐plastic and rigid‐glass LECs are rationalized, culminating in insights that can be useful for the rational design of LEC devices with suppressed self‐heating and high performance.