A Competitive Electron Transport Mechanism in Hierarchical Homogeneous Hybrid Structures Composed of TiO2 Nanoparticles and Nanotubes

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• 作者：Jongmin Choi ; Gyeongho Kang ; Taiho Park
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：February 24, 2015
• 年：2015
• 卷：27
• 期：4
• 页码：1359-1366
• 全文大小：567K
• ISSN：1520-5002

文摘

We prepared well-defined hierarchical structures comprising doubly open-ended TiO₂ nanotube (NT) arrays covered with various layers of few-nanometer-sized TiO₂ nanoparticles (NPs) to investigate the electron collection mechanisms in homogeneous hybrid structures. We found that competitive electron transport pathways (direct transport through the NT and randomized transport through the NPs) are present in the homogeneous hybrid structures. Photoinduced electrons generated at the few-nanometer-sized TiO₂ NPs directly connected with TiO₂ NTs (e.g., isolated and single-layer NPs on the surface of NTs) dominantly traveled to the NTs. With an increasing number of TiO₂ NP layers, photoinduced electrons are randomly transported through the TiO₂ NP layers. Enhanced light harvesting and efficient charge collection (鈭?5%) caused by the increased amounts of dye loading and the direct transport through the NT, respectively, are achieved in a structure with 鈭?.4 layers of few-nanometer-sized TiO₂ NPs, resulting in a power conversion efficiency of 11.3% with a J_SC value (22.9 mA/cm²) close to the theoretical value (鈭?6 mA/cm²) of a N719-based dye-sensitized solar cell.