Efficiency enhancement of solar cells employing TiO2 as the active material has been successfully done by addition of copper(II) nitrate trihydrate (Cu(NO3)2.3H2O) in the TiO2 dispersant, and post-treatment with sodium hydroxide (NaOH) after electroplating of copper particles at spaces inside the TiO2 film. Homogeneously mix of TiO2 particles in the solution of Cu(NO3)2.3H2O was deposited on a transparent conducting electrode using a spray method. To reduce electron-hole recombination, copper particles were deposited on the space between TiO2 particles by electroplating. A sample of solar cell was made by sandwiching a polymer electrolyte between the film and a counter electrode. Copper(II) nitrate trihydrate of 1.4 wt% and 5 volt electroplating voltage are able to produce an optimum power conversion efficiency of 0.35% with a fill factor of 0.31. To achieve higher efficiency, post treatment with NaOH was performed to increase the ionic transfer ability in electrolyte and we observed efficiency up to 1.24% with a fill factor of 0.34.

Dye-sensitized solar cell (DSSC) which employed natural dye from black rice has been successfully fabricated and improved its performance by depositing interconnected copper (copper bridge) on the space between TiO2. The copper bridge has significant role in minimizing recombination of electron-hole which occurred in TiO2 surface by trapping electron and facilitating to anode. The presence of interconnected copper nanoparticle in the space between TiO2 nanoparticle was confirmed by Scanning Electron Microscopy (SEM) and X-Ray Diffractometer (XRD). The current-voltage (I-V) characterization of DSSC solar cells by using Keithley 617 was also performed to investigate performance of solar cells under sun illumination in varying intensities. It is found that performance of copper coated DSSC solar cells (efficiency 0.35% and fill factor 0.35) is higher than DSSC without copper coating (efficiency 0.17% and fill factor 0.35). This result is consistent with impedance spectroscopy analyzing where the internal resistance of copper coated DSSC solar cells is lower than DSSC without coated. It is concluded that performance of DSSC increasing with decreasing of internal resistance. Our finding is higher than other researcher reports in Ref. [13] and [14] with similar structure and kind of natural dye. In addition, this paper also reports the use of polymer electrolyte which employing polyvinyl acetate (PVA) containing lithium ion to maintain long-term stability of device.

We propose a solar cell design using the combination of titanium dioxide (TiO 2 ) and graphite as active photon absorbing materials. TiO 2 absorbs photons of nearly ultraviolet wavelengths to produce electron-hole pairs, while graphite is expected to absorb photons of longer wavelengths. Although many authors have claimed that graphite is a semimetal, we observed that a model of a solar cell containing TiO 2 only as the active material behaves exactly the same as a model containing graphite only as the active material. Additionally, we observed that a model of a solar cell made using a composite of TiO 2 and graphite as the active material had much higher efficiency than solar cells made using TiO 2 -or graphite-only active materials. Although the highest efficiency we report here is approximately 1 %, our proposed solar cell structure is promising for mass application, especially in low-income settings, owing to its easy and flexible fabrication, and easy largescale application.

-Development of nanomaterial research has provided tremendous changes in technological advances. However, theories that have been used for this (bulk material) is not appropriate to explain the behavior of materials in nanometer size. Therefore, in this paper we explain the phenomenon of nanometer size effect of the metal to its electrical conductivity. Theory approach is used to derive the mathematical relationship between the nanometer scale of metal and the electrical conductivity. Electrical conductivity curve to the particle size is obtained from the results of mathematical formulation has been solved by simple calculation. Based on this curve, we obtained a decrease in the electrical conductivity as the size of nanoparticles decreases. These results were validated with experimental results from several sources that show the similar trends between the model and experimental results.

We report the fabrication of a dye-sensitized solar cell (DSSC) using low-cost materials (carbon ink from an inkjet printer coated on glass as the counter electrode) and made by a combination of spray deposition and doctor blade methods. We noted that the efficiency of the DSSC with the carbon-coated electrode (1.13%) was comparable to that with a platinum-coated counter electrode (1.16%). We also proposed an equivalent circuit for this solar cell. The value of the charge-transfer resistance was determined both experimentally and analytically, and we found that both approaches produced the same results. Moreover, we improved the efficiency of DSSC based carbon by depositing copper nanoparticle into the space between Titanium Dioxide (TiOv2) nanoparticle using electroplating methods.

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An understanding of the characteristics and parameters of ocean wavescan help to explan and develop the potential of ocean waves. One of the efforts thatcan be done in understanding the characteristics of ocean waves is to use a simulator of ocean waves. In this study, a laboratory scale ocean wave simulator was designed. This simulator is equipped with a wave generator system in the form of a DC motor and was developed with a size of 120 cm x 25 cm x 20 cm. The simulator performance test was carried out by varying the speed of theDC motor and the depth of the water to determine the effect on the parameters of the waves formed. The wave parameters measured are the height and the wavelength. The results show that the designed ocean wave simulator can produce waves that resemble a sinosuidal curve. The measured wave height on the simulator is directly proportional to the water depth. While the wavelengthis inversely proportional to the speed of the DC motor.Abstrak: Pemahaman mengenai karakteristik dan parameter gelombang laut dapat membantu dalam memahami dan mengembangkan potensi gelombang laut. Salah satu upaya yang dapat dilakukan dalam memahami karakteristik gelombang laut adalah dengan memanfaatkan simulator gelombang laut. Pada penelitian ini dilakukan rancang bangun simulator gelombang laut skala laboratorium.  Simulator ini dilengkapi dengan sistem pembangkit gelombang berupa motor DC dan dikembangkan dengan ukuran 120 cm x 25 cm x 20 cm. Pengujian performa simulator dilakukan dengan memvariasikan kecepatan motor DC dan kedalaman air untuk mengetahui pengaruhnya terhadap parameter gelombang yang terbentuk. Parameter gelombang yang diukur adalah tinggi dan panjang gelombang. Hasil penelitian menunjukkan simulator gelombang laut yang dirancang dapat menghasilkan gelombang yang menyerupai kurva sinosuidal. Tinggi gelombang yang terukur pada simulator berbanding lurus dengan kedalaman air. Sedangkan panjang gelombangnya berbanding terbalik dengan kecepatan motor DC.

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