No abstract

To unravel the influence of the temperature and plasma species on the growth of single-crystalline metal oxide nanostructures, zinc, iron, and copper foils were used as substrates for the study of nanostructure synthesis in the glow discharge of the mixture of oxygen and argon gases by a custom-made plasma-enhanced horizontal tube furnace deposition system. The morphology and microstructure of the resulting metal oxide nanomaterials were controlled by changing the reaction temperature from 300 to 600 °C. Experimentally, we confirmed that single-crystalline zinc oxide, copper oxide, and iron oxide nanostructures with tunable morphologies (including nanowires, nanobelts, etc.) can be successfully synthesized via such procedure. A plausible growth mechanism for the synthesis of metal oxide nanostructures under the plasma-based process is proposed and supported by the nanostructure growth modelling. The results of this work are generic, confirmed on three different types of materials, and can be applied for the synthesis of a broader range of metal oxide nanostructures.

In this work, we develop a radio-frequency plasma-enhanced horizontal tube furnace deposition system to directly grow graphene nanowalls (GNWs) on inverted pyramid (IP) silicon without using catalysts and fabricate GNWs/IP silicon Schottky junction solar cells. The morphology, microstructure, and optical and electrical properties of the synthesized GNWs and IP silicon are investigated. It is shown that GNWs are distributed on the whole surface of the IP silicon and feature an outstanding electrode network. Moreover, in situ optical emission spectroscopy measurement is carried out to investigate the growth process and chemical reaction mechanism of GNWs under the plasma-based process. Due to the excellent light-trapping structure of IP silicon and outstanding electrode network of GNWs, the photovoltaic conversion efficiency (PCE) of the pristine GNWs/IP Si solar cells can reach up to 4.05% via controlling the growth time of GNWs. A PCE of 7.2% can be achieved for the GNWs/IP Si solar cells by combining HNO3 p-doping treatment and spin-coating TiO2 as an antireflective layer. This work plays a vital role in the development of a simple and advanced process for the realization of high-efficiency graphene-based solar cells.

An effective method to directly produce high-quality graphene nanowalls (GNWs) on quartz substrates was demonstrated using an advanced self-assembled ratio-frequency plasma-enhanced horizontal tube furnace deposition system under different growth times from 60[Formula: see text]s to 150[Formula: see text]s at a substrate temperature of 850[Formula: see text]C without using any catalyst. The synthesized well-connected three-dimensional GNWs feature outstanding electrical and optical performance: the sheet resistance varies from 1053 [Formula: see text]/[Formula: see text] to 342 [Formula: see text]/[Formula: see text], while the corresponding transmittance ranges from 90.4% to 67.8% at a wavelength of 550[Formula: see text]nm under different growth times. We have also demonstrated that GNWs can be used as transparent conductive electrodes for perovskite solar cells. The highest photovoltaic conversion efficiency of 6.93% can be obtained for the GNWs deposited at a growth time of 120[Formula: see text]s. Hence, our study paves a new way of using GNWs as transparent conductive electrodes in perovskite solar cells.