| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 105 === A recently emerging class of solid-state hybrid organic–inorganic perovskite-based solar cells,using CH3NH3PbX3(X=Cl,Br,I) as light harvesting materials, had demonstrated remarkably high power conversion efficiencies of nearly 21%. Most state-of-the-art perovskite solar cells typically have a device structure that is based on a hightemperature sintered metal oxide(compact TiO2) as electron transporting layer(ETL) which may cause the limitation of perovskite solar cells to be deposited on flexible substrates and affect their compatibility with fabrication processes in multi-junction solar cells. In this work, the utilization of atomically thin titania (atomic Ti0.87O2) deposited at room temperature as an ultra-thin electron transporting layer in perovskite solar cell was demonstrated.Through Langmuir-Blodgett deposition process at room temperature,atomic Ti0.87O2 was conformally deposited on FTO substrate with a high coverage and eliminated the requirement of high temperature process (over 500C) to deposit compact TiO2. The incorporation of multi-layer Ti0.87O2 (around 5 nm) effectively decreased the recombination of electron and hole and leaded to a reduced leakage current. This resulted in a promising device performance (14.05%) that is compatible to the device fabricated using high-temperature sintered metal oxide as electron selection layer. More importantly, we find devices using atomic Ti0.87O2 as electron transporting layer have a better stability in atomsphere. After 30 days, the atomic Ti0.87O2 devices remain about 70% of their original efficiency, unlike compact TiO2 devices, which remain 10% of original efficiency. With the atomic Ti0.87O2 electron transporting layer, we can successfully make a whole low temperature solution process, an atomically thin film ETL, and a stable deivces.
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