Design and characterization of carbon inks for perovskite solar cells

Energy demand in the world has been increasing in every day because of increasing human population and improving technology. Between the 2016 and 2040 it is estimated that energy needs of the humanity will expand 30%. Traditional energy sources couldn't meet the demand so researchers have focused on the new and renewable energy sources. Solar energy is one of the important renewable energy source can decrease the energy needs in the world. Especially in the improved countries many researches have focused on this topic to improve the efficiency and getting commercilization. According to World Energy Council datas at the end of the 2016, Germany is the leader solar installed capacity of the world. In this area, Turkey doesn't have sufficient installed solar capacity, however, installed solar capacity are growing day by day. Solar cell converts sunlight to the electricitiy with semiconductor materials and part of the solar energy sources. It can be divided into three categories and perovskite solar cell is the lastest and encouraging generation of this solar cells because of their low cost, easy to produce and high efficiency. Perovskite solar cell structure is based on with hole transport layer and without hole transport layer. For hole transport layer generally has been used spiro-Ometad which is high cost material. On the other hand, in the HTM-free perovskite solar cell, perovskite acts as a hole transport layer and conductivity is supplied from carbon electrode or gold electrode. Carbon electrode has been prefered because of its high conductivity, low cost, abundant in nature and environmentally friendly properties. Electrode can be obtained from bare carbon type or carbon ink/paste. Carbon ink generally contains carbon material, binder and solvent. Carbon material can be different type of carbon such as activated carbon, carbon black, graphtie, graphene, carbon nanotubes etc. In the ink formulation, carbon supply electrical conductivity of the ink and binder is responsible for the ink stability. According to solvent type carbon ink may be dissolved in water based or polymer based solvents. Carbon ink is preffered while the high conductivity is requested. Solar cell, supercapacitor, bioelectronic, textile, tissue engineering and sensor are main application areas of the carbon ink. In this thesis, carbon inks were designed and characterized. First carbon ink was processed at room temperature on the FTO substrate and its electrical conductivity and morphologic structures were determined. Moreover, it was applied on the perovskite solar cell and measured the photovoltaic properties. As second type, carbon inks containing carbon particles obtained by carbonization of two different type of coffee waste with different ratio of activation material were prepared and their resistivity and morphology were investigated. In the third type of carbon inks, doped polymer structures were used and processed at low temperature on FTO surface in order to measure their electrical resistivity and to determine their morphologic structures. The lowest resistivity inks obtained from all the ink types were applied by doctor blade method as electrodes on perovskite solar cell and the performance of the cells were tested.