In this study, we found that the work functions (Φ(w)) of solution-processable, functional graphene/carbon nanotube-based transparent conductors were readily manipulated, varying between 5.1 and 3.4 eV, depending on the nature of the doping alkali carbonate salt. We used the graphene-based electrodes possessing lower values of Φ(w) as cathodes in inverted-architecture polymer photovoltaic devices to effectively collect electrons, giving rise to an optimal power conversion efficiency of 1.27%.

We present an antireflection structure consisted of irregular nanopillars to increase light extraction efficiency of flexible organic light-emitting devices. The nanopillars were made by imprinting the anodized aluminum oxide on polycarbonate substrates. The thermal viscosity effect formed the nanopillars with tapered shapes. Such nanopillars show excellent antireflection properties for a wide range of incident angles and wavelengths. The normal transmittance was improved from 85.5% to 95.9% for 150-nm-height nanopillars. The transmittance was greatly improved from 52.8% to 89.1% at 60° incident angle. With this antireflection structure, the device efficiency was improved 69% as compared to devices with flat substrates. Due to wide-angle antireflection, the image contrast ratio was also significantly improved.

We employed direct-current electric fields (dcEFs) to modulate the chemotaxis of lung cancer cells in a microfluidic cell culture device that incorporates both stable concentration gradients and dcEFs. We found that the chemotaxis induced by a 0.5 lM/mm concentration gradient of epidermal growth factor can be nearly compensated by a 360 mV/mm dcEF. When the effect of chemical stimulation was balanced by the electrical drive, the cells migrated randomly, and the path lengths were largely reduced. We also demonstrated electrically modulated chemotaxis of two types of lung cancer cells with opposite directions of electrotaxis in this device. V C 2014 AIP Publishing LLC. [http://dx

We present an antireflection structure consisted of tapered nanopillars to simultaneously increase light extraction efficiency and image contrast of flexible organic light-emitting devices. The nanopillars were made by imprinting the anodized aluminum oxide on polycarbonate substrates. The thermal viscosity effect formed the nanopillars with tapered shapes. Such tapered nanopillars show excellent antireflection properties for a wide range of incident angles and wavelengths. The transmittance was greatly improved from 52.8% to 89.1% at 60 o incident angle for 150-nm-height nanopillars. With this antireflection structure, the device efficiency was improved 69% as compared to devices with flat substrates. Due to wide-angle antireflection, the ANSI image contrast ratio was also significantly improved.