Study of Amorphous Carbon Nitride Films Aiming at White Light Emitting Devices

Abstract

The possibility for white light emitting devices using carbon nitride (CNx) thin films has been studied. Microwave ECR-plasma CVD and RF-sputtering apparatuses have been used for the formation of CNx thin films. In both cases, CH4 was used as the source or sub-source of carbon in order to investigate the effect of hydrogenated carbon nitride for luminescence. The cathodeluminescence (CL) measurement of the film grown by ECR-plasma CVD method showed three peaks of R/G/B. The photoluminescence (PL) measurement of the film grown by RF-sputtering also showed the red peak, which could not be observed in the film without hydrogen. Together with the X-ray Photoelectron Spectroscopy (XPS) analysis data, we concluded that the red peak originates from C-H bonds and blue peak from C-N bonds.

Impact of the annealing temperature on Pt/g-C 3 N 4 structure, activity and selectivity between photodegradation and water splitting

“…Figure 3 B) shows that the band gap decreases when the synthetic temperature is increased up to 550 °C, in correlation with the C/N ratio. This is in line with previous findings on amorphous carbon doped with nitrogen suggesting that as the size of the sp 2 C=N clusters increases, the state density of π bonding in the sp 2 cluster increases leading to a decrease of the optical band gap [13][14][15]. It has to be noted that the material synthetized at 600 °C presents two different band gaps, which has not been reported in the literature so far [6,8,9,16].The lower one being in the continuity with the band gaps obtained for the materials synthesized at lower temperature while the higher one is closer to the data obtained at 650 °C.…”

“…The two samples synthetized at the highest temperatures are displaying an absorbance shoulder around 500nm, matching with their darker color [9]. The band gap of the different photo-catalysts were calculated using the Tauc plot for a direct allowed transition (n=1/2) [13]. Figure 3 B) shows that the band gap decreases when the synthetic temperature is increased up to 550 °C, in correlation with the C/N ratio.…”

Effect of processing temperature on structure and photocatalytic properties of g-C3N4

“…This behavior can be attributed to the extension of the polymeric network of the g-C 3 N 4 by connecting more tri-s-triazine units and the increase of the bond length of the sp 2 C-N clusters at higher temperatures[55]. Both of these facts increase the size of the sp 2 C-N clusters and typically the larger sp 2 clusters show a smaller optical band gap[56,57]. In principle, a larger band gap together with enhanced light absorbance ability, should improve the photocatalytic performance of g-were tested for photocatalytic removal of NO under UV and visible light irradiation, in order to compare their ability in air purification.…”

Synthesis and luminescence mechanism of multicolor-emitting g-C3N4 nanopowders by low temperature thermal condensation of melamine

“…Owing to their special properties such as the super hardness, low density, reliable chemical inertness, water resistivity, wear resistance and biocompatibility23, carbon nitride was regarded as the promising materials applied in the emission devices, surface modification, medical science and photocatalysis, etc. Wang et al have reported that using carbon nitride as photocatalysis to acquire the hydrogen from water2, and Iwano et al have reported that the amorphous carbon nitride films can be applied to the white light emitting devices4. Among the carbon nitride materials, graphite like carbon nitride (g-C 3 N 4 ) has attracted considerable attention due to its unique optical and electronic properties, which is promising to be applied as photoelectric nanodevices, chemical sensors, metal free photocatalysis, photovoltaic solar cells, etc 5678…”

“…Nowadays, several works about the visible photoluminescence (PL) of carbon nitride have been reported41011. However, the systematic investigation on the tunable PL of carbon nitride is scarce, and it is much rarer for g-C 3 N 4 compounds.…”