IV. New Molecular Design & Synthesis of Advanced Organic/Inorganic
Hybrid Semiconductor Materials for Highly Efficient Hybrid Solar Cells
Perovskite solar cells have been strongly considered to be another alternative to the conventional photovoltaic devices including silicon-based solar cell technology as challenging and emerging solar cell technology. The operating principle of perovskite solar cells is the same as that of DSSCs and perovskite solar cells have been investigated from liquid electrolyte DSSCs at an early stage and then from solid-state electrolyte DSSCs, due to their Excellent Capability of Strong and Broad Light Absorption and Photophysical/Photoelectrical Properties including Exciton Binding Energy, Ambipolar Transport Capability. Two solar cells have three key material components such as n-type TiO2 photoanode, which is coated and sensitized with dyes or perovskite crystals, and redox-active electrolytes including hole transporting materials as solid-state electrolytes. Perovskite solar cells gave the conversion efficiency up to 22.1% reported by KRICT in Korea, in a few years. But, we still have to solve their problems such as Long-term Device Stability and Toxicity of Pb Atom after device breakdown or destruction for practical uses.
Quantum dot solar cell is based on multi electron generation that is impact ionization process, producing tow or more electrons for on photon absorption. The efficiency of quantum dot solar cell is theoretically known as 60%. We have performed the design and characterization of such devices for approaching theoretical efficiency.
Multi-treatment TiO2 materials and X(Nb and N)-doped TiO2 photoanodes were studied for high efficiency of DSSCs. The TiCl4 treatment improved electron transport property in the nanocrystalline TiO2 photoanodes. And also it exhibited good contact with TCO and to remove defect site in TiO2, thus enhancing JSC and VOC in DSSCs. The Nb- and N-doped TiO2 photoanodes exhibited to shift conduction band edge of TiO2 (negative or positive) that matches the lowest unoccupied molecular orbit (LUMO) level of the dye, (thus increasing VOC or JSC).
