Preparation, Characterization And Photoelectric Properties Of Carbon Nitride Nanocone Arrays

Carbon nitride nanomaterials have attracted much attention around the world due to their excellent properties, such as high hardness, corrosion resistance, wear resistance, high temperature resistance, high conductivity and excellent field electron emission properties. Over the years, the researching work on carbon nitride nanomaterials were mainly focusing on carbon nitride nanoparticles and thin films, but few research about carbon nitride nanocones were reported. Owing to their unique morphology, structure, optical and electrical properties, carbon nitride nanocone (CNNC) array have great application prospects in the cathode materials of field emission display, scanning probe pins and the electrodes of solar cells.The contents of this paper comprise two parts:one is the preparation of CNNC arrays on Ni catalyst layers by glow discharge plasma chemical vapor deposition method (GPCVD), the other is the synthesis of carbon nitride films using pulsed laser ablation deposition (PLD) method.1. Prepared CNNC arrays under different CH4/N2 ratios by GPCVD. FESEM photos show that the sizes of CNNC array gradually increase when increasing CH4/N2 ratio. TEM, SAED and EDS results show that the CNNCs are made of the black Ni pipes and amorphous CNX gray areas. At the CH4/N2 ratio of 1/20, β-C3N4 crystal structure was found near the black Ni pipes. When CH4/N2 ratio increases from 1/20 to 1/5, the proportion of C elements in CNNC is increased, but the proportion of N elements decreases. UV-visible absorption spectra show that in the 200-900 nm wavelength range, the samples have good absorption for the incident light, and the absorption rate is increased to 78%-86% as the CH4/N2 ratio increases to 1/5. Electrical measurements show that when CH4/N2 ratios increases from 1/80 to 1/5, the resistivity of CNNC reduces from 1.01×10-3 Ω·m to 6.45×10-5 Ω·m, indicating that the samples have nice conductivity. Meanwhile, organic polymer infiltration experiments show that CNNC arrays have very nice wetability to the P3HT:PCBM absorber layers. These results indicate that CNNC arrays have good electrical conductivity, high light absorptionon wide spectrum and good wettability to the polymer, thus such nanocone arrays have good application prospects in optoelectronic devices and polymer/inorganic hybrid solar cells.2. Prepared carbon nitride films under different N2 pressure by PLD. FESEM photos show the size of the particles in the film surface gradually increases when increasing N2 pressure. XPS results show that the nitrogen content in the film is essentially the same when increasing N2 pressure, but the sp2/sp3 proportion in C1s peaks increases, indicating the degree of graphite in film is increased. Raman results show that the ID/IG ratio is gradually reduced when increasing N2 pressure, also showing the extent of graphite in samples is increased, which are consistent with the previous XPS analysis results. The tauc fitting of UV-visible transmittance spectra shows that the optical band gap of carbon nitride films increases with the increase of N2 pressure, indicating that the size of sp2C cluster in films may be a major factor for affecting the optical band gap.