TiO2/Cu2O ince film fotovoltaik hücrelerin karakterizasyonu

Photovoltaic cells (PVs) generate electricity by using sunlight. Although they have been known since years, they have recently been famous with increasing renewable energy demand. Nowadays, silicon solar cells are mostly used. But to achieve lower cost and improve manufacturing for large scale, different kind of PVs should be established. While PVs' demand grow, new materials should be supplied. In this perspective Cu2O is an attractive material as an absorber and TiO2 is known as a large band gap semiconductor. When these two semiconductors are brought together, a p-n junction is created which is promising as a solar cell. In this thesis, TiO2/Cu2O thin film PV characterization was studied. Characterization focused on optical properties of thin films as transmittance, absorbance, band gap values and behaviors under illumination related with their structural properties. Thin film deposition was processed by pulsed laser deposition method. In the first part, variable temperatures, pressures and transparent conductive layers were used to achieve anatase crystal phase for TiO2 layer. Under 0.4 mbar oxygen pressure and 350°C, 450°C, 550°C temperatures, thin film samples were deposited on FTO substrates. The XRD results showed that as-deposited films were amorphous so films were subjected to annealing process and anatase-rutile transformation was observed. Band gap values decreased after annealing; 3.45-3.29 -3.15 eV, respectively. Under 500°C deposition temperature and 0.05 mbar, 0.2 mbar oxygen pressures, thin films were deposited on ITO substrates. XRD results showed that as-deposited films were anatase+rutile mixed phase and anatase phase, under these pressures. Band gaps were 3.28-3.33 eV respectively. Second part was obtaining the Cu2O phase by adjusting the oxygen partial pressure. Under 0.2 mbar Ar atmosphere and 2x10-4mbar-2x10-2 mbar oxygen partial pressures, samples were deposited on TiO2 layers which were growth on FTO. Third part was applying the individual layer deposition parameters to overall photovoltaic cell. Overall PV structure was poor anatase and Cu2O phases. To investigate the electrical properties of photovoltaic cells, an illumination set-up was arranged. Set-up properties and sample response results under illumination were discussed in the results part. Key words:Photovoltaic cells, semiconductor, p-n junction, thin film, transmittance, absorbance, band gap.