Simple molecular structures capable of emitting over the entire visible range are still a challenge. Planar molecular structures have the drawback of fluorescence quenching in the solid state thus limiting their application fields. Combining long range excimer/exciplex emissions with a compound emission have been used to get white light. In this work, a series of new coumarin derivatives having a planar structure have been synthesized and characterized. The effects of systematic variation in alkyl chain functionalization providing morphological variations that permit interesting solid state emitting properties have been discussed simultaneously with electrochemical behavior and OLED (organic light emitting diode) device applications. Carbon chains containing 0-16 carbon atoms have been studied in order to conclude the results that systematic changes in alkyl group substitution can be utilized as a tool to tune the emitting color of these planar coumarins. Alkyl chains were introduced by O-acylation and O-benzoylation reaction on the hydroxyl group of parent coumarin 5. Thus the present strategy is also helpful in establishing a template to control the unproductive interchromophore electronic couplings.Solid state fluorescence properties support the crystal studies. Theoretical studies are also in agreement with experimental data. Electroluminescence of Device 2 with a turn on voltage (V on ) around 5-6 V having s-CBP doped with 1% of 8 having alkyl substitution of 2-carbons is found to exhibit white emission with CIE co-ordinates of (0.29, 0.34) which is close to white emission while the alkyl substitution of 14-carbons (compound 17) in Device 7 (V on ¼ 7 V) exhibited green emission. Thus a strategy helpful to tune the electroluminescence has been discussed.

A novel series of thermally stable yellow light emitting fluoranthenes with an amine donor and a nitrile acceptor was prepared from a ketene-S,S-acetal under mild conditions without using an organometal catalyst. The organic light emitting device of yellow fluoranthene 10b exhibited substantially low turn-on voltage (2.6 V) and maximum brightness of 470 Cd/m(2) with luminance efficiency of 2.0 Cd/A without using any dopant.

The fabrication of organic solar cells on paper substrate is attractive as it paves the way for roll‐to‐roll‐processed modules on more ecologically friendly substrates. A paper‐substrate solar‐cell process is successfully demonstrated. Commercially available paper with coatings from the polyvinyl family of materials is made suitable for electronic‐device fabrication. Smoothing layers of polyvinyl formal (PVF) with a knife‐edge coater give them an acceptable root mean square roughness of around 2.6 ± 0.2 nm. This paper is shown to be compatible with subsequent organic‐solar‐cell device fabrication with a variety of solvents including polar solvents. Top‐illuminated solar cells with blends of either poly(3‐hexylthiophene) and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM), or poly({4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl}{3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl}) and PCBM as photoactive layer having power conversion efficiencies up to 3.37% and 6.44%, respectively, are fabricated. A statistically significant number solar cells with different areas from multiple runs are fabricated and their solar cell parameters are analyzed and discussed. The results show strong promise for solar‐cell fabrication on environmentally friendly paper substrates.

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New Hole-Transporting Materials (HTMs) based on Tröger's Base scaffold serve as respectable alternatives of NPB with high Tgs.