In this work, a soft lithographic approach has been developed to duplicate photoinduced surface-relief-gratings (SRGs) of azo polymer films to generate the surface pattern replicas composed of different materials on various substrates. For this purpose, thin films of an epoxy-based azo polymer (BP-AZ-CA) were prepared by spin-coating, and SRGs with different structures were inscribed by exposing the films to interference patterns of Ar(+) laser beams at modest intensity (150 mW/cm(2)). Using the azo polymer films as masters, stamps of poly(dimethylsiloxane) (PDMS) were prepared by replica molding. The PDMS stamps were then used to transfer the solutions of poly(3-hexylthiophene) (P3HT), multiwalled carbon nanotube (MWNT), and BP-AZ-CA to different substrates by contact printing. Through this process, surface pattern replicas made of the functional materials were obtained. The pattern formation and quality depended on the factors such as the solution concentration, contacting time in the printing process, and printing pressure. Under the proper conditions, the printed patterns showed the same grating periods as the masters and the same relief depths as the stamps (replicas of the masters). This approach, showing some attractive characteristics such as the easiness of master preparation and the versatility of soft fabrication processes, can be applied to the fabrications of optical functional surfaces, sensors, and photonic devices.

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In this work, a soluble perylene-derivative dye, N, N 0 -didodecyl-3,4,9,10-perylene tetracarboxylic diimide (PDI), was used to improve the photovoltaic performance of poly(3-hexylthiophene) (P3HT)/ZnO bulk heterojunction cells through blending with the composite. Results show that by incorporation of PDI in the P3HT/ZnO composite, the light absorption and exciton separation can be significantly improved. The photocurrent under white-light irradiation can be increased from 6.35 to 9.55 mA/cm 2 . Solar decay experiment shows that V OC of the ITO/PEDOT:PSS/P3HT:ZnO:PDI/Al device decreases rapidly to almost zero in 1 h under persistent white-light illumination. After placing a 420 nm cutoff filter between the cell and the xenon lamp, the stability of the cell can be significantly improved. The device performance can maintain about 80% of the original value within 30 h and I SC degraded to zero after 142 h. The addition of PDI into the P3HT/ZnO device up to 5 wt% does not show observable effect on the solar cell decay behavior. r

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