Brian Yuliarto

FABRICATION OF ZINC OXIDE-BASED DYE-SENSITIZED SOLAR CELL BY CHEMICAL BATH DEPOSITION

Zinc oxide film has been fabricated by converting flower-like structure of zinc carbonate hydroxide made by chemical bath deposition technique. Flower-like structure is employed as charge transport network of dye-sensitized photoanode. Analysis of current density–voltage characteristic shows deposition temperature and deposition time of chemical bath deposition influence photovoltaic performance. Analysis of electrochemical impedance spectroscopy reveals short electron lifetime and high effective electron diffusion coefficient of zinc oxide-based dye-sensitized solar cell.

Synthesis of Nanoporous TiO 2 and Its Potential Applicability for Dye-Sensitized Solar Cell Using Antocyanine Black Rice

Nanoporous mesostructure TiO2 powders were synthesized by sol-gel method, with as a precursor in methanol solution. The Pluronic PE 6200 of block copolymer was used as the pores template. It was found from XRD measurements, both at C and C calcination temperatures, that the sol-gel technique yielded the nanoporous TiO2 with anatase phase. Based on adsorption characterization using BET method, the TiO2 samples have surface area of 108 /g and 88 /g for calcination temperatures of C and of C, respectively. From small-angle neutron scattering (SANS) patterns, TiO2 samples were observed to have nanoporous structures with pore sizes between 22–24 nm. The TiO2 also have order degree which depends on the calcination temperature. The potential applicability of the resulting TiO2 is confirmed for dye-sensitized solar cell (DSSC), composed of nanoporous anatase TiO2 and natural dye from antocyanine black rice. UV-Vis measurement of dye extracted from the black rice indicated that the antocyanine chelate can propagate into the TiO2 nanoporous network. The short circuit photocurrent density (Jsc) under 100 mWc reached 1.287 mAc with open circuit photovoltage (Voc) of 550 mV and the fill factor of 33.4%. The results show that the hybrid organic-inorganic structures are very attractive for future low-cost devices.

Development of battery management system for cell monitoring and protection

Battery has an important role as energy storage in electricity system utilization such as in electric vehicle and in smart microgrid system. Battery Management System (BMS) is needed to treat the dynamics of energy storage process in the battery in order to improve the performance and extend the life time of battery. In this paper, BMS cell monitoring and protection has been designed and tested for Lithium Ferro Phosphate (LFP) battery cells. The BMS cell monitoring function has been able to measure the battery parameters such as the voltage and current dynamics of each cell. The data taken from the BMS cell monitoring experiment is used to estimate the state of charge (SOC) of battery which is based on coulomb counting with coulomb efficiency ratios. The BMS cell monitoring function has successfully demonstrated the presence of unbalanced cell voltages during both processes of charging and discharging as well. From the analysis, the existence of capacity and energy fades was also investigated for every discharging and charging cycles. Based on the BMS cell protection experiment results, overcharged and over discharged protections have successfully been demonstrated for the battery cells. The charging process is disabled when the voltage of the corresponding battery cell exceeds its high limit (HLIM) at 3.65V, and the battery will be available for charging when all of the cell voltages are below their boundary limits (CAVL) at 3.3V. The discharging process will be disabled when the battery cell voltage is lower than the corresponding low limit (LLIM) at 2.5 V. The battery will be available again when all battery cell voltages are above their discharge available (DAVL) voltage at 2.8V. The proposed BMS cell monitoring and protection has shown its function as a data acquisition system, safety protection, ability to determine and predict the state of charge of the battery, and ability to control the battery charging and discharging.

Improved Performances of Ethanol Sensor Fabricated on Al-Doped ZnO Nanosheet Thin Films

The effect of Al-doped ZnO (AZO) to the sensitivity improvement of ethanol vapor sensor was investigated. The pure ZnO and AZO thin films were synthesized by chemical bath deposition method. Analysis of the crystal structure, chemical composition, and morphology of the samples are carried out using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). XRD results show that the phase formed is polycrystalline Zn, while the EDS measurements show that the composition of after synthesized AZO were 1.48 at%, 2.90 at%, and 3.55 at%. The SEM results showed flowerlike microstrcuture and nanosheet shaped are formed in the resulting thin films, which are captured by the formation of sheets of transparent structure in AZO. Moreover, the resulting ZnO and AZO sensors were exposed to the different concentration of ethanol vapor as much as 200, 400, and 600 ppm, respectively. The measurement of vapor sensor system performance was tested to analyze the sensitivity and the responsiveness of the AZO thin films. The sensors have highest sensitivity at certain amount of Al doping. It is obtained that the optimum sensitivity of the sensor is investigated at the sample of 2.9 at% Al-ZnO. The sensitivity for pure ZnO sample at concentration of 200, 400, and 600 ppm of ethanol were 70.88%, 78.21%, and 88.57%, respectively. The highest sensitivity for AZO samples is 95.29% at low ethanol concentrations (200 ppm) and 96.68% at the high concentration (parts per million), respectively.

A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31+G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31+G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100mW·cm-2 yields a short-circuit current density (Jsc) of 3.23mA/cm2, a photovoltage (Voc) of 0.48V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dyes absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2μm, the fastest electron transit of 0.22ms, and the longest electron lifetime of 4.29ms.

SnO2 Nanostructure as Pollutant Gas Sensors: Synthesis, Sensing Performances, and Mechanism

A significant amount of pollutants is produced from factories and motor vehicles in the form of gas. Their negative impact on the environment is well known; therefore detection with effective gas sensors is important as part of pollution prevention efforts. Gas sensors use a metal oxide semiconductor, specifically SnO2 nanostructures. This semiconductor is interesting and worthy of further investigation because of its many uses, for example, as lithium battery electrode, energy storage, catalyst, and transistor, and has potential as a gas sensor. In addition, there has to be a discussion of the use of SnO2 as a pollutant gas sensor especially for waste products such as CO, CO2, SO2, and NOx. In this paper, the development of the fabrication of SnO2 nanostructures synthesis will be described as it relates to the performances as pollutant gas sensors. In addition, the functionalization of SnO2 as a gas sensor is extensively discussed with respect to the theory of gas adsorption, the surface features of SnO2, the band gap theory, and electron transfer.

Performance of Natural Carotenoids from Musa aromatica and Citrus medica var Lemon as Photosensitizers for Dye-Sensitized Solar Cells with TiO2 Nanoparticle

Several natural dyes have been extracted from tropical fruit shells such as Musa aromatica and Citrus medica var Lemon fruit shells. The resulting dyes have been used as sensitizer at dye sensitized solar cell (DSSC). The main pigments, which are carotenoids, was obtained by extraction and purification at dark room. Ethanol and water are used as solvents. The dyes have been characterized through UV–Vis spectrophotometer. The thin film of TiO2 anatase has been sintered at 450°C to enhance film compactness. According to the experimental results, the DSSC conversion efficiency which has been prepared by carotenoid dye from Musa aromatica fruit shell extract is 0.21%, 0.614 V of open-circuit voltage (VOC), 0,280 of short-circuit current density (JSC) mA/cm2, 56 μW of maximum power (Pmax) and 0.43 of fill factor (FF). Then, the DSSC conversion efficiency which has been prepared by carotenoid dye from Citrus medica var Lemon fruit shell extract is 0.05%, 0.460 V of VOC, 0.093 mA/cm2 of JSC, 14 μW of Pmax and 0.44 of FF. The measurement of I-V curve demonstrated that carotenoid was potential component as sensitizer for DSSC.

Density functional study of adsorptions of CO2, NO2 and SO2 molecules on Zn(0002) surfaces

We report on a theoretical study of adsorptions of CO2, NO2 and SO2 molecules on ZnO(0002) surfaces using density functional theory-based (DFT-based) calculations. These adsorptions are done on perfect and defective ZnO(0002) surfaces. We find that all of these molecules are chemically adsorbed on the perfect ZnO(0002) surface. In the presence of Zn vacancy, we find that the surface is only active toward SO2 molecule. On the hydroxylated ZnO(0002) surfaces, CO2 and SO2 molecules can react with the preadsorbed OH molecule to form various adsorbates such as: carboxyl (COOH), bicarbonate (CO3H), sulfonyl hydroxide (SO3H), SO3 and water. However, NO2 molecule cannot react with the pre-adsorbed OH molecule and only physically adsorbed on the surface.

Ground and excited state properties of high performance anthocyanidin dyes-sensitized solar cells in the basic solutions

The aglycones of anthocyanidin dyes were previously reported to form carbinol pseudobase, cis-chalcone, and trans-chalcone due to the basic levels. The further investigations of ground and excited state properties of the dyes were characterized using density functional theory with PCM(UFF)/B3LYP/6-31+G(d,p) level in the basic solutions. However, to the best of our knowledge, the theoretical investigation of their potential photosensitizers has never been reported before. In this paper, the theoretical photovoltaic properties sensitized by dyes have been successfully investigated including the electron injections, the ground and excited state oxidation potentials, the estimated open circuit voltages, and the light harvesting efficiencies. The results prove that the electronic properties represented by dyes’ LUMO-HOMO levels will affect to the photovoltaic performances. Cis-chalcone dye is the best anthocyanidin aglycone dye with the electron injection spontaneity of −1.208 eV, the theoretical open circuit ...

Modifications of Multi-Walled Carbon Nanotubes on Zinc Oxide Nanostructures for Carbon Monoxide (CO) Gas Sensitive Layer

A novel functional material has been synthesized by modification of multi-walled carbon nanotubes (MWNTs) with nanostructured zinc oxide (ZnO). Multi-walled carbon nanotubes have unique electronic and photonic properties, as well as nanostructured zinc oxide [. Both have advantages when combined as to provide a material with extremely high surface area-to-volume ratio, which is required for the sensor structure. So far, CNT-based gas sensors have been investigated for the detection of H2, N2, NO2, and NH3 [. In this study, modification of multi-walled carbon nanotubes with nanostructured zinc oxide is conducted by simple screen printing and ultrasonic spray pyrolysis (USP) methods, which consists of the fabrication of MWNTs paste, the formation of ZnO sol, and calcination. The deposited thin films are then characterized using several characterization techniques, such as X-ray diffraction and SEM. The performance testing of the sample as a CO gas sensitive layer has also been investigated and the measurement results on 100 ppm CO gas exposure at 250°C showed the sample had a sensitivity of 85%, response time of 5 minutes and recovery time of 20 minutes.