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Amorphous carbon (a-C) film is a unique material that attracts the attention of scientists to be investigated. Nitrogen- and boron- doped amorphous carbon (a-C:N and a-C:B) have been deposited on ITO glass substrates by using nanospray method. Palmyra sugar is heated at temperature 250o C for 2.5 hours to obtain a-C. Boric acid (H3BO3) and amonium hidroxide (NH4OH) are used as the sources of boron doping and nitrogen doping. a-C:N and a-C:B are made by the variations of mole ratio for doping and amorphous carbon, that are 1:15 and 1:20. Then, these samples are dissolved into mixed dymethyl sulfoxide (DMSO) and aquades. The exfoliation process of samples has been done by applying ultrasonic cleaner for 2 hours and also centrifugated at 4000 rpm for 45 minutes. Electrical conductivity and band gap are measured by using four point probe and UV Vis. The results show that electrical conductivity increases but band gap decreases than pure a-C. Furthermore, the larger mole ratio of a:C-N and a-C:B also increases conductivity and decreases band gap, resulting between 5.5×10-1S/cm – 6.1×10-1 S/cm and 1.43 eV – 1.71 eV.

Structure of amorphous carbon can be composed of sp2 (graphite), or sp3 (diamond), or a combination of both, depending on their fractions. Therefore, many researchers were exploring to use it as solar cell material. This research used the amorphous carbon of bio-product as a basic material in the form of palmyra sugar which was synthesized through the heating and doping process to produce n-type and p-type semiconductors. This research aims to analyze the effect of dopant and deposition time on electrical properties. The heating process was carried out at 250°C and the doping process was carried out by adding NH4OH for a-C:N and H3BO3 for a-C:B. The deposition process was carried out by the nano-spray method using a variety of deposition time on the ITO substrate. The result of scanning electron microscopy (SEM) showed that the film thickness increased with the increase of deposition time. Besides, the result of four-point probe (FPP) showed that the dopant can increase electrical conductivity, but the film thickness did not influence it. The electrical conductivity obtained was 5x10-1 - 6x10-1 S/cm. And the result of further analysis, it can be concluded that electrical conductivity was still in the range of semiconducting material.

Amorphous carbon films have been explored and used in a wide variety of applications. With the n-type and p-type amorphous carbon film, it can be used to make p-n junctions for solar cells. This research aims to study the structure of boron- and nitrogen-doped amorphous carbon (a-C:B and a-C:N) films. This research uses the basic material of bio-product from palmyra sugar to form amorphous carbon. Amorphous carbon was synthesized by heating the palmyra sugar at 250°C. The results of XRD showed that the doped films produce an amorphous carbon phase. PES was used to analyze the bonding state of dopants in the sample. B4C, BC3, and BC2O bonds formed in a-C:B, while pyridine and pyrrolic formed in a-C:N.

In this study an investigation has been conducted on the effect of reduced graphene oxide (rGO) coating on increasing the value of Lithium Ferro Phosphate (LFP) electrical conductivity. This coating process uses a variation of the mass ratio of LiFePO4/rGO by 90%:10%, 70%:20%, and 67%:33%. The LiFePO4 precursor was prepared using the sol-gel rute from the main commercial materials, namely Li2CO3 powder as a source of lithium ions, FeCl2.4H2O as a source of iron and NH4H2PO4 powder as a phosphate source. As for the coating used rGO extracted from coconut shell waste. The samples were calcined with temperature variations of 600°C, 650°C and 700°C in an argon environment for 10 hour. The phase purity and crystal structure of LiFePO4 were analyzed using XRD. The analysis of data from XRD was done using the the Match!, Rietica, and MAUD software. Based on the results of XRD analysis, LiFePO4 with high purity and good crystallinity was obtained when the sample was calcined at temperature of 700°C. The results of the MAUD analysis show that the best size of LiFePO4 crystal is 86,54 nm. LiFePO4/rGO nanocomposite was successfully synthesized by mechanical ultracentrifugation method. The characterization of the value of electrical conductivity, carried out using a four-point probe. The results show that the greater the percentage of rGO, the higher the value of electrical conductivity. The mass ratio of 67% LiFePO4 and 33% rGO shows an increment in good conductivity values, from the original order of 10-8 S/cm to the order of 10-4 S/cm.