A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient organic devices is realized by the continuous blade-only method.

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Understanding the effects of conjugated polymer structures on exciton lifetimes and morphologies within bulk heterojunction (BHJ) films is a necessary step toward the development of better organic solar cells. Studying the impact of a polymer's structure on the optical, morphological, and performance characteristics of a device can lead to advances in the design of new polymers. In this study, we synthesized carbon-and siliconbridged cyclopentadithiophene-(CPDT-) based polymers and determined their photophysical properties and morphologies by measuring the exciton lifetime distributions in their BHJ films. The silicon-bridged CPDT-based polymer/[6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) BHJ exhibited a higher degree of luminescence quenching, suggesting that thermodynamically favorable mixing on the molecular scale and nanoscale phase separation occurred simultaneously in the blend film. We attribute this favorable morphology to the presence of strong π-π stacking in the silicon-bridged CPDT-based polymers. Under AM 1.5 G illumination (100 mA cm -2 ), a device incorporating the silicon-bridged CPDT-based polymer and PCBM (1:2, w/w) gave an overall power conversion efficiency of 3.5% with a short-circuit current of 9.0 mA cm -2 , an open-circuit voltage of 0.72 V, and a fill factor of 53.6%. ' INTRODUCTIONPolymer solar cells have attracted much scientific interest because of their potential to reduce fabrication costs by taking advantage of solution-deposition methods and high stability compared with dye-sensitized solar cells. 1-5 One of the important factors affecting the power conversion efficiency (PCE) in polymer solar cells is the morphology of the BHJ films. The ideal morphology would feature (i) a high level of mixing between donors and acceptors, to create a large interfacial surface area that allows exciton dissociation, and (ii) percolating pathways across the film for the transport of photogenerated electrons and holes. 6-9 A number of methods, including thermal annealing, 10-13 solvent annealing, 14-17 and the use of processing additives, [18][19][20][21] have been proposed to efficiently modulate polymer film morphology on the nanoscale. Thermal and solvent annealing can induce the self-organization of conjugated polymers, leading to stronger interchain interactions. A recently developed mixed-solvent approach involves the addition of alkanedithiols into the solvent used to fabricate the solar cell devices. These alkanedithiols selectively dissolve [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM), but not poly(3-hexylthiophene) (P3HT) or any of the other polymers used. This method allows efficient phase separation to occur during the drying process, leading to favorable morphologies for the transport of the carriers to their respective electrodes.In addition to the approaches mentioned above, the use of silole-containing polymers is another promising method for controlling film morphology and improving device performance. Many groups have reported that replacing a carbon atom with a silic...

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