We investigated optical properties of subwavelength patterned metal gratings for photonic device application. It was known that optical transmittance of metal films with subwavelength periodic hole arrays can be controlled by applying a dielectric overlay to the film and the films can act as wavelength or frequency selective filters. Following advancement in lithography technology it could be applied up to complementary metal oxide semiconductor (CMOS) image sensors (CIS) by patterning metal layers placed on each pixel’s photo detective device. However it is not easy to replace organic color filters applied on CIS up to date because the standard CIS structure has multi-metal layers, thick dielectric layers, and too thick metal layers. In this work, we explore possibility to integrate the metal film into a CIS chip and present an alternative proposal by computer simulation utilizing finite-difference time-domain (FDTD) method. We applied aluminum (Al) for the metal film and the dispersion information associated with Al was derived from the Lorentz-Drude model. We expect that this work could contribute to search to apply subwavelength patterned metal gratings to photonic devices.
In this study, the influence of an active cell design on the power conversion efficiency (PCE) of a monolithic organic
photovoltaic (OPV) module was investigated using experimental methods and circuit simulation. For circuit simulation
using computer simulation-based study, the organic PV cell was described by a circuit-based two-diode model and the
modules were simulated under several conditions including shading effect, diode model parameters, series resistance and
shunt resistance, etc. A unit organic PV cell as a reference device and four types of monolithic organic PV modules with
different active cell length were fabricated together on the same glass substrate. The characteristics of the fabricated unit
OPV cell were measured and the electrical parameters were extracted to use them for the simulation of four types of
monolithic organic PV modules. To analyze the influence of OPV cell design on the PCE of monolithic organic PV
modules, the current-voltage (I-V) characteristic curves and the PCEs of the four type monolithic OPV modules with
different active cell length were obtained and compared with the simulated results. The simulated I-V curves were
matched well with the measured I-V curves for the four types of monolithic organic PV modules with different active
cell length. The highest PCE of the monolithic OPV module was 2.86 % with the active cell length of 11.6 mm. We
expect that this work is meaningful to enhance the performance of a monolithic OPV module to a certain extent and it
offers a method to design a high-efficiency large-area monolithic OPV module.