— Synthesized single-walled carbon nanotubes (SWCNTs) consist of a mixture of chiralities and therefore a post-synthesis separation is essential to separate them based on electronic type i.e., metallic (m-SWCNT) or semiconducting (s-SWCNT) for device applications. A key parameter to measure the effectiveness of separation process is the enrichment composition percentage between m-SWCNT and s-SWCNT, which can be estimated via several methods based on optical characterizations. In this paper, we compare the composition percentage estimations from 3 different methods based on Raman spectroscopy and UV-Vis optical absorption spectroscopy. The estimation methods are radial breathing mode (RBM) peak analysis, optical absorption area under curve (OUA) and first derivative amplitude of the optical absorption curve (FDA). Four different SWCNT sources were used in this study, which were subjected to post-synthesis separation process via agarose gel chromatography. Raman and UV-Vis spectroscopy measurements were carried out on all samples, before and after separation. From the estimations, we observed firstly that there are some variations on the estimated enrichment compositions between different methods, although the values are comparable. Secondly, for some SWCNTs samples, only a certain estimation method showed reliable composition percentage. The results presented in this work may provide viable options for characterizations of SWCNTs as there is no direct method to quantify the absolute composition percentage of SWCNTs based on electronic type. Keywords—single-walledcarbon nanotube, separation, electronic type, optical characterization, purity percentage.

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This study is to investigate the morphology and electrical characteristics of single-wall carbon nanotubes (SWCNTs) thin film deposition using air brush technique. A deposition setup consisting of a conventional artist air brush was developed and used to deposit SWCNT thin films and therefore the resulting film’s characteristics need to be investigated to gauge its suitability in producing uniform monolayer. The SWCNTs used were synthesized via Direct Injection Pyrolytic Synthesis (DIPS) method, with diameters ranging from 0.8 to 3 nm. The substrate was deposited using an airbrush with varying nozzle to study its effect to the resulting SWCNTs thin films’ characteristics. Subsequently, scanning electron microscope (SEM) were used to inspect the morphology and surface topography, and followed by preliminary electrical measurements. The result shows that good dispersion promotes uniform distribution of SWCNTs over large area of glass substrate. Moreover, the electrical measurement revealed that at 1 V, best morphology produced highest current at a nozzle distanceof 10 mm (15.3 μA) and the lowest current at a nozzle height of 4 mm (3.24 μA). From the results presented, it is demonstrated that conventional artist airbrush setup can be effectively used to deposit monolayer thin film of SWCNT with high degree of uniformity. This research is necessary for the process of depositing-controlled CNT thin film network, which can influence the material characteristics and performance of the variety of CNT-based device applications.

CNT is a novel material with exceptional properties. SWCNT thin films have been used in many different applications. To fabricate the SWCNT film, various methodologies have been introduced, however, the problem of fabricating uniform SWCNT thin film remains unsolved. Spray coating technique (SCT) is the most effective method for producing a uniform SWCNT thin film. The CNT thin films were deposited on glass substrates via SCT with different nozzle distances (from 2.5 cm to 12.5 cm). The morphological, topological, electrical and optical properties of CNT thin films were characterized using appropriate techniques. The electrical analysis depicted that the sheet resistance of thin films reduced from 40220 Ω/sq. to 1330 Ω/sq. as the spray nozzle distance was increased from 2.5 cm to 10 cm sheet resistance reached 2133 Ω/sq. for 12.5 cm which confirmed the concentration of CNT was highest at 10 cm nozzle distance. The optical analysis of the CNT thin films gave transmittance values in percentage of 64%, 60%, 52%, 43%, and 46%, respectively for the nozzle distance of 2.5 cm, 5 cm, 7.5 cm, 10 cm, and 12.5 cm. Transmittance percentage decreased from 2.5 cm to 10 cm nozzle distance, indicative of an uniform film coverage of CNT layer. The findings of this study could be a platform for producing an optimized CNT thin film using a SCT for optoelectronic devices.