Use of titanium-based inorganic perovskite materials in solar cells

This thesis focused titanium-based dicesium titanium diiodide tetrabromide (Cs2TiI2Br4) and dicesium titanium hexabromide (Cs2TiBr6), which are all-inorganic perovskite materials. The Cs2TiBr6 perovskite was synthesized in powder form. The Cs2TiI2Br4 and Cs2TiBr6 perovskites were dissolved and deposited onto substrates using a spin-coating method. X-ray diffraction (XRD) analyses revealed that the Cs2TiI2Br4 perovskite exhibited the highest peak value at ~28.5°, while the Cs2TiBr6 perovskite had the highest peak intensity at ~28.8°. Cs2TiBr6 decomposed within 1 hour under atmospheric conditions. At the end of the 10 hours, two distinct peaks emerged at 28.50° and 29.24°. The forbidden bandgap energy values (Eg) were calculated from the Tauc plots. The band gap of Cs2TiBr6 powder was found to be 1.82 eV while the band gaps of Cs2TiI2Br4 and Cs2TiBr6 thin films were determined as 1.45 eV and 1.88 eV, respectively. The resistivity, Hall mobility, and carrier density values for the Cs2TiBr6 powder perovskite pellet were obtained as 1.13×10^4 Ω·cm, 502 cm^2V^-1s^-1, and 1.1×10^12 cm^-3, respectively. For the Cs2TiBr6 thin films, the values of resistivity, Hall mobility, and carrier density were found to be 27.62 Ω·cm, 21.15 cm^2V^-1s^-1, and 1.1×10^16 cm^-3, respectively. Perovskite solar cells FTO/TiO2/Cs2TiI2Br4/P3HT/Ag and FTO/TiO2/Cs2TiBr6/P3HT/Ag were produced, and their current density-voltage characteristics were analyzed in the dark and under illumination. It was observed that these manufactured solar cells exhibited photovoltaic behavior. The power conversion efficiencies for the FTO/TiO2/Cs2TiI2Br4/P3HT/Ag and FTO/TiO2/Cs2TiBr6/P3HT/Ag perovskite solar cells were calculated as 5.1×10^-4% and 3.2×10^-4%, respectively.