We demonstrate novel plasmonic organic solar cells (OSCs) by embedding an easy processible nanobump assembly (NBA) for harnessing more light. The NBA is consisted of precisely size-controlled Ag nanoparticles (NPs) generated by an aerosol process at atmospheric pressure and thermally deposited molybdenum oxide (MoO3) layer which follows the underlying nano structure of NPs. The active layer, spin-casted polymer blend solution, has an undulated structure conformably covering the NBA structure. To find the optimal condition of the NBA structure for enhancing light harvest as well as carrier transfer, we systematically investigate the effect of the size of Ag NPs and the MoO3 coverage on the device performance. It is observed that the photocurrent of device increases as the size of Ag NP increases owing to enhanced plasmonic and scattering effect. In addition, the increased light absorption is effectively transferred to the photocurrent with small carrier losses, when the Ag NPs are fully covered by the MoO3 layer. As a result, the NBA structure consisted of 40 nm Ag NPs enclosed by 20 nm MoO3 layer leads to 18% improvement in the power conversion efficiency compared to the device without the NBA structure. Therefore, the NBA plasmonic structure provides a reliable and efficient light harvesting in a broad range of wavelength, which consequently enhances the performance of organic solar cells.
To measure a spatial resolution of CT scanner, several methods have been developed using bar pattern, wires and thin
plates. While these approaches are effective to measure two dimensional MTF, it is not easy to measure directional MTF
using those phantoms. To overcome these limitations, Thornton et al. proposed a method to measure directional MTF
using sphere phantoms, which is effective only when the cone angle is small. Recently, Baek et al. developed a method
to estimate the directional MTF even with a larger cone angle, but the proposed method was analyzed using a noiseless
data set. In this work, we present Wiener and Richardson-Lucy deconvolution techniques to estimate the directional MTF,
and compare the estimation performance with that of the previous methods (i.e., Thornton’s and Baek’s methods). To
estimate directional MTF, we reconstructed a sphere object centered at (0.01 cm, 0.01 cm, 10.01 cm) using FDK
algorithm, and then calculated plane integrals of the reconstructed sphere object and the ideal sphere object. The plane
integrals of sphere objects were used to estimate the directional MTF using Wiener and Richardson-Lucy deconvolution
techniques. The estimated directional MTF was compared with the ideal MTF calculated from a point object, and
showed an excellent agreement.