Optically addressed spatial light modulators (OASLM) are promising for holographic applications and optical limiters. Self-activated OASLMs can operate as autonomous energy devices, opening the route to stand-alone laser protection devices and smart windows. They are mainly based on liquid crystal (LC) devices, integrated with inorganic photovoltaic substrates such as LiNbO3:Fe or dye-sensitized TiO2. While robust, they also suffer from several restrictions such as high costs, low performances and/or small device area.
In this work, we propose a new type of an autonomous modulator. Blends of electron-donating (D) conjugated polymers and electron-accepting (A) fullerene molecules were used as a photovoltaic thin films and integrated into liquid crystal device. Such D/A bulk heterojunctions are the major building block of solution-processed organic solar cells and are known to convert incident light into electrical energy. In our case, the organic layer generates a photovoltaic field that is used to control the LC alignment under illumination. We carried out cross-polarized intensity measurements on this photovoltaic-LC device to demonstrate the expected occurrence of a light–dependent birefringence change, without an applied voltage. In this way, by combining solution-processed organic photovoltaic thin films with optical responsive liquid crystals, our work paves the way to low cost and large area self-sustained optical devices.
Experimental results concerning the influence of plasmon effect from silver nanoparticles on the organic photovoltaic
device performance are presented. The metallic nanoparticles (NPs) are placed on top of ITO layer using a physical
vapor deposition technique. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) followed by an
interpenetrated poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) blend layer are then
spin-coated. The aluminum electrode is finally evaporated on. Photovoltaic properties compared to devices without NPs
are shown. A spectrophotometric characterization is carried on. Moreover, a ToF-SIMS measurement is performed in
order to obtain the depth chemical profiles of solar cell containing such NPs. Silver NPs diffusion inside other layers of
the cell is investigated.