Characteristics of a Silicon Nanowires/PEDOT:PSS Heterojunction and Its Effect on the Solar Cell Performance

The interfacial energy-level alignment of a, silicon nanowires (SiNWs)/PEDOT:PSS heterojunction is investigated using Kelvin probe force microscopy. The potential difference and electrical,distribution in the junction are systethatically revealed. When the PEDOT:PSS layer is covered at the bottom of the SiNW array,,an abrupt junction is formed at the interface whose characteristics are mainly determined by-the unifonnly doped Si bulk. When the PEDOT:PSS layer is covered on the top, a hyperabrupt junction localized at the top of the SiNWs forms, and, this characteristic depends on the surfaee properties of the SiNWs. Beeause the Calculation shows that the absorption of light from the SiNWs and the Si bulk are equally important, the bottom-coverage structure leads to better position matching between the depletion and absorption area and therefore shows better photovoltaic performance. The dependence of J(SC) and V-OC on the junction characteristic is discussed.