EFFICIENCY IMPROVEMENT OF GRAFIT /TIO2 BASED SOLAR CELLS THROUGH DEPOSITION OF MINERAL IONS AND OPTIMIZATION OF LIOH CONCENTRATION IN POLYMER ELECTROLYTE

• Main Author: Yanto Rahman, Dui
• Format: Dissertations
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/42258
• Institution: Institut Teknologi Bandung

Solar energy is an alternative energy source that can solve energy problems in the future. Solar cells, as devices capable of converting solar energy into electrical energy without polluting the environment, must be developed continuously to make it a source of energy capable of meeting the energy needs of man and substitute for limited sources in the future. To meet human energy needs, solar cells should be made from cheap materials, easy production processes and achieve a high level of efficiency. Organic solar cells appear as the third generation after bulk silicon and inorganic thin-film solar cells. This solar cell has been developed to address the problems of first and second-generation solar cells, namely the high price of solar cells due to the complexity of solar cell production technology coupled with the high price of the materials used. the efficiency produced is relatively high. The most widely developed organic solar cells are Dye Sensitized Solar Cells (DSSCs), which are solar cells that use a dye (dye) as a photon absorbing material. In general, this solar cell structure consists of a front electrode layer in the form of ITO or FTO, an electron transport layer in the form of TiO2, an absorbing photon layer in the form of a dye, a hole transport layer in the form of electrolyte liquid containing iodine / iodide and platinum as the electrode counter. These solar cells can be produced using much simpler technology and relatively cheaper materials than first- and second-generation solar cells. However, the yield produced is still low and has not been comparable to that of the first and second-generation solar cells. The low efficiency obtained is not proportional to the price of the material used for each layer of solar cell structure, although it is still much cheaper than the first and second-generation solar cells. The development of organic solar cells using inexpensive materials for all layers of the solar cell structure is essential for producing inexpensive organic solar cells with fairly good efficiency. The goal of this study is to address the challenges of developing organic solar cells, including the use of inexpensive materials for each layer of the structure and simpler manufacturing methods. For the front electrode layer, the FTO is still used. As an electron transport layer which generally uses expensive Degusa TiO2, it will be replaced by metallic copper particles which will be deposited in the void space of the photon absorbing materials by the electroplating process. The presence of a metal bridge serves as trappinng of electrons to prevent electron-hole recombination. Absorbing photon layers that typically use synthetic dyes containing ruthenium bipyridine complexes such as N719 will be replaced with a low-cost graphite / TiO2 composite. Graphite which has a small bandgap absorbs a spectrum of sunlight whose energy is low, so it should produce high currents Isc, while TiO2, which has a wide bandgap, should produce high Voc. High Isc and Voc will have a big effect on the efficiency of solar cells. The deposition of several photon absorption layer layers (Cu/graphite/TiO2) was also performed to increase the intensity of photon absorption, which may have effect on the increase of the current and the efficiency of solar cells. As a substitute for the expensive iodine / iodide, a PVA.LiOH electrolytic polymer will be used. Counter-electrodes that generally use platinum will be replaced by cheap aluminum. The structure of the Cu/graphite /TiO2 photon absorber layer has an efficiency of 0.12% with a current of 85 ?A. The use of more than one layer of Cu/graphite/TiO2 made it possible to obtain an efficiency of 1.09% with a current of 450 ?A with anumber of layers of two. The increase in efficiency is caused by the wider range of light absorption of ultraviolet light entering the visible light region and by increasing the intensity of photon absorption through increasing the number of absorbing layers of photons. In addition, a hole scavenging mechanism is also used by placing ionic material in void spaces between particles of absorbing photonic material, thereby capturing holes created in the photon absorbing material. The placement of the ionic material is carried out using mineral water during the dispersion process. The minerals must be deposited during the heating process of the anode film. This mechanism can reduce electron-hole recombination processes much more significantly than electron trapping mechanisms. Optimization of the LiOH content in PVA.LiOH was also carried out with the aim of increasing the conductivity of polymer electrolytes so that it can reduce the combination of electrons with holes. This can be seen from the increase in fill factor values as well as the efficiency of solar cells. With this structure, the highest efficiency of 6.97% has been produced with fill-factor of 0.48 using graphite as a photon absorbing material which is inserted with ionic material and the optimal LiOH content in PVA.LiOH is 17%. The use of composite TiO2/graphite as a photon absorbing material with variations in the content of TiO2 to graphite was also carried out with the aim of increasing the Voc value as well as the fill-factor and efficiency of this solar cell. With this structure the highest efficiency has been produced at 9.77% with Voc 1.37 V and fill-factor 0.56 using 20% TiO2 content against graphite. It is predicted that the use of inexpensive materials in each layer of the solar cells and the use of easy method of fabrication will produce low cost solar cells with a sufficiently high efficiency so that they can finally be easily produced on a large and massive scale.