Characterization of eu doped TiO2 thin films and application to the inverted type polymer solar cells

In this thesis, TiO2 semiconductor metal oxide material is successfully produced in the form of thin film and Eu metal is doped. Doped and undoped TiO2 thin films were characterized by the characterization methods such as SEM, XRD, XPS, and crystal structure, morphology, elemental components and optical properties are investigated. The effect of Eu addition on the structural and optical properties was investigated. It was observed that the Eu doping concentaration almost did not affect the morphology of the thin films but distorted their crystal structures. It was obtained that fabricated doped and undoped TiO2 thin films have anatase phase crystal structures and (101) peaks of the thin films shift the smaller angles. Produced TiO2 thin films were used as electron carrier and hole blocking layer in the inverted type polymer solar cells. For this, solar cells with ITO / TiO2: Eu / P3HT: PCBM / Ag structure in which the P3HT: PCBM active layer is used as photo-absorber have been produced and characterized. TiO2 thin films were prepared using the sol-gel method. Ti-n-butoxide was used as the Ti source and Eu-acetate was used as the Eu source. TiO2: Eu thin films with additive ratios of %0, %1, % 5, %7 and %10 Eu were produced and used as the electron transport layer. The active layer of P3HT: PCBM was prepared by mixing 1:1 ratio of P3HT and PCBM in 1,2 di-chlorobenzene. The solution was coating on TiO2: Eu layers by spin coating. The devices were characterized by taking current-voltage curves with a semiconductor characterization system under the conditions of 100 mW / cm2 light power and AM 1.5. When the I-V curves were examined, it was observed that as the Eu addition increased, the series resistance decreased and the short circuit current increased to % 5 Eu doping ratio. The contribution of the Eu-doping in the TiO2 thin films used as the electron-transporting layer has been successfully improved the efficiency of the inverted type polymer solar cell. Power conversion efficiency of the device, which was produced with pure TiO2 of % 1.16, was increased to % 2.47 with % 5 Eu doping ratio. Key Words: Oxide materials, sol-gel processes, impurities in semiconductors, photoconductivity and photovoltaic, doping of metal oxides.