The main bottleneck in inkjet printing (IJP) is a stable and jettable ink formulation. This paper discusses the ink formulation for the small molecule phosphorescent dopant/host system. The study involves the estimation of Hansen solubility parameters (HSP) to formulate inkjet‐printed ink of an iridium complex‐based phosphorescent material, bis(4‐phenylthieno[3,2‐c]pyridinato‐N,C2') (acetylacetonate) iridium(III) (PO‐01) as dopant and 4, 40‐bis (carbazol‐9‐yl) biphenyl as the host of the emissive layer. Based on dopant and host HSP analyses, toluene and methyl benzoate are chosen as ink solvents. Our ink is stable for a month and can be replicated with great accuracy. The interaction of individual drops is examined in detail since resolution or film quality is highly influenced by the drop formation and spread on a substrate. Finally, an inkjet‐printed emissive layer is demonstrated on both glass and flexible substrates. The fabricated devices exhibit the maximum current efficiency and luminance of 6.4 cd A−1 and 5781 cd m−2. A technique is also shown to print large‐area organic light‐emitting diode (OLED) devices having different patterns without patterning or pixelization of the active area of the electrodes. Up to 80 × 80 mm2 large‐area OLED tiles are made using IJP of the emissive layer.

Self‐healable elastomeric materials (PUAxPU10–x‐PDMS, x = 4, 6, or 8) have been synthesized and utilized as substrates or encapsulation films on the top of barrier films (deposited on polyethylene terephthalate (PET) substrates) to improve their gas barrier properties for packaging applications. Hexa‐layer (HL) assembly consisting of two inorganic 2D nanoplatelets, including Mg‐Al layered double hydroxide (LDH) and hexagonal boron nitride (hBN), and two oppositely charged polyelectrolytes, that is, polyethyleneimine (PEI) and poly(sodium styrene‐4‐sulfonate) (PSS), have been developed by alternative depositions of HL (i.e., PSS/LDH/PSS/PEI/hBN/PEI) sequentially. Then, a layer‐by‐layer technique is applied to produce multiple assemblies of hexa‐layer (HL)n and reduce water vapor transmission rate (WVTR) values of elastomeric PUA8PU2‐PDMS and PET substrates. The optimum WVTR values of 7.1 × 10−3 and 8.0 × 10−3 g m−2 day−1 are achieved using barrier PET/(HL)8/PUA8PU2‐PDMS (125/3/1 µm) and PUA8PU2‐PDMS/(HL)8 (125/3 µm) films, respectively. The self‐healable barrier PUA8PU2‐PDMS and PUA8PU2‐PDMS/(HL)8 films recover their initial WVTR values after self‐healing of mechanically damaged films. Organic light‐emitting diodes (OLEDs) encapsulated with PET/(HL)8/PUA8PU2‐PDMS and PUA8PU2‐PDMS/(HL)8 have 9–10 times longer half‐lifetime values than bare OLEDs. Accordingly, this report develops transparent, stretchable, and self‐healable gas barrier films for next‐generation flexible electronic device packaging applications.

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