Efficient excimer emission is demonstrated in white organic light‐emitting diodes (see figure) based on platinum(II)[2‐(4′,6′‐difluorophenyl)pyridinato‐N, C2′)](2,4‐pentanedionato) utilized in devices incorporating the novel host material 2,6‐Bis(N‐carbazolyl)pyridine (26mCPy). External quantum (power) efficiencies of 15.9 % (12.6 lm W–1) are realized at 500 cd m–2.

The organization of organic semiconductor molecules in the active layer of organic electronic devices has important consequences to overall device performance. This is due to the fact that molecular organization directly affects charge carrier mobility of the material. Organic field‐effect transistor (OFET) performance is driven by high charge carrier mobility while bulk heterojunction (BHJ) solar cells require balanced hole and electron transport. By investigating the properties and device performance of three structural variations of the fluorenyl hexa‐peri‐hexabenzocoronene (FHBC) material, the importance of molecular organization to device performance was highlighted. It is clear from 1H NMR and 2D wide‐angle X‐ray scattering (2D WAXS) experiments that the sterically demanding 9,9‐dioctylfluorene groups are preventing π–π intermolecular contact in the hexakis‐substituted FHBC 4. For bis‐substituted FHBC compounds 5 and 6, π–π intermolecular contact was observed in solution and hexagonal columnar ordering was observed in solid state. Furthermore, in atomic force microscopy (AFM) experiments, nanoscale phase separation was observed in thin films of FHBC and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) blends. The differences in molecular and bulk structural features were found to correlate with OFET and BHJ solar cell performance. Poor OFET and BHJ solar cells devices were obtained for FHBC compound 4 while compounds 5 and 6 gave excellent devices. In particular, the field‐effect mobility of FHBC 6, deposited by spin‐casting, reached 2.8 × 10−3 cm2 V−1 s and a power conversion efficiency of 1.5% was recorded for the BHJ solar cell containing FHBC 6 and PC61BM.

A new solution processable nanocomposite material has been prepared via the Heck coupling of octavinylsilsesquioxane with a selected bromoaromatic hole transport compound. Resultant electroluminescent devices show an 18% improvement in external quantum efficiencies over their small molecule analogues.

Near-infrared (NIR) emission is demonstrated from phosphorescent organic light-emitting diodes containing blends of polymeric host and heavy metal complex, iridium(III) bis(1-pyrenyl-isoquinolinato-N,C′) acetylacetonate. The devices exhibit exclusive NIR emission with a peak value at 720nm. Forward light output exceeds 100μW∕cm2, and the external quantum efficiency is nearly 0.1%. These values are shown to increase upon using a hole blocking layer in the device architecture.

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