은 나노입자 플라즈모닉 효과에 의한 염료감응 태양전지의 광전류 상승

Abstract

In the past few years, a field of plasmonics has emerged as a rapidly expanding new area for materials and device researches. A plasmon is a quantum of plasma oscillation. Surface plasmons indicate that excitations of the conduction electrons at the interface between a metal and a dielectric medium. Metal nanoparticles have a plenty of free electrons or free electron gas on their surface where the free electrons are oscillated by fixed positive charge at the interface. This phenomenon is called ‘plasmonic effect’. One of representative plasmonic effects is light trapping which makes longer light path-length in absorption layers of solar cells. Through this light trapping, plasmonic effect contributes to the increase of light absorption and consequently photocurrent of solar cells. Therefore, the plasmonic effects with silver nanoparticles are applied to improve the energy conversion efficiency for dye-sensitized solar cells (DSSCs). We embedded silver nanoparticles into mesoporous TiO2 layers by attaching silver nanoparticles incorporated in electrospun poly(methyl methacrylate) (PMMA) nanofibers. After the deposition, the polymer template was removed through sintering process. And then, sub-micron TiO2 scattering layer was deposited by typical doctor-blading method. Due to sub-micron TiO2 scattering layer and silver nanoparticles, it is expected that light trapping may occur in photoanode area. Light trapping allows effective light absorption and the wavelength of light absorption may be broadened to some extent. This was confirmed by both the increase in the incident photon to current efficiency (IPCE), and the current-voltage curve (J-V curve). In addition, effects of a placement of silver nanoparticles treated with TiCl4 to prevent iodine corrosion were also investigated. According to those experiments, we figured out the optimal position of silver nanoparticles for plasmonic effect and a solution against corrosion between silver nanoparticles and iodide/triiodide redox couple.