High-Efficiency and Low-Cost Solar Cells of a New Type, Having Semiconductors Modified with Ultrafine Metal Particles

点击翻译按钮获取中文摘要

Photoelectrochemical and solid-state solar cells of a new type, prepared by use of n-Si wafers modified with ultrafine metal particles, have been studied with an aim to improving the characteristics. A Langmuir-Blodgett layr of ultrafine platinum (Pt) particles on a water surface was transferred onto an n-Si wafer and, by this method, the mutual separation of the Pt particles on n-Si was controlled on a nanometer scale, From quantitative experimental studies on the dependences of the open-circuit photovoltage (V_<OC>) on the Pt-particle density and the cell temperature as well as that on the hole diffusion length of n-Si modified with the Pt particles, we have revealed that the n-Si modified with the Pt particles at a small density acts as an ideal minority-carrier diode at room temperature and generates a very high V_<OC>. We also attempted to use porous n-Si as a method to deposit ultrafine Pt islands and succeeded in obtaining a fairly high V_<OC> of 0.59V.Furthermore, we mede detailed studies on the solid-state solar cells prepared by the vacuum deposition of an indium-tin-oxide (ITO) layr on the Pt-particle modified n-Si, and have clarified that the direct deposition of an ITO layr on the Pt-modified n-Si causes many defects (surface recombination centers) near the Si surface, leading to small V_<OC>'s, but the pre-deposition of a thin copper-phthalocyanine layr before the ITO deposition suppresses the formation of such defects, incresing V_<OC> to 0.58V.We also studied "ITO/Si-oxide/Si" solar cells to clarify the structure and properties of the thin films and interfaces.