Well-Defined Nanostructured, Single-Crystalline TiO2 Electron Transport Layer for Efficient Planar Perovskite Solar Cells

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• 作者：Jongmin Choi ; Seulki Song ; Maximilian T. Hörantner ; Henry J. Snaith ; Taiho Park
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：June 28, 2016
• 年：2016
• 卷：10
• 期：6
• 页码：6029-6036
• 全文大小：538K
• 年卷期：0
• ISSN：1936-086X

文摘

An electron transporting layer (ETL) plays an important role in extracting electrons from a perovskite layer and blocking recombination between electrons in the fluorine-doped tin oxide (FTO) and holes in the perovskite layers, especially in planar perovskite solar cells. Dense TiO₂ ETLs prepared by a solution-processed spin-coating method (S-TiO₂) are mainly used in devices due to their ease of fabrication. Herein, we found that fatal morphological defects at the S-TiO₂ interface due to a rough FTO surface, including an irregular film thickness, discontinuous areas, and poor physical contact between the S-TiO₂ and the FTO layers, were inevitable and lowered the charge transport properties through the planar perovskite solar cells. The effects of the morphological defects were mitigated in this work using a TiO₂ ETL produced from sputtering and anodization. This method produced a well-defined nanostructured TiO₂ ETL with an excellent transmittance, single-crystalline properties, a uniform film thickness, a large effective area, and defect-free physical contact with a rough substrate that provided outstanding electron extraction and hole blocking in a planar perovskite solar cell. In planar perovskite devices, anodized TiO₂ ETL (A-TiO₂) increased the power conversion efficiency by 22% (from 12.5 to 15.2%), and the stabilized maximum power output efficiency increased by 44% (from 8.9 to 12.8%) compared with S-TiO₂. This work highlights the importance of the ETL geometry for maximizing device performance and provides insights into achieving ideal ETL morphologies that remedy the drawbacks observed in conventional spin-coated ETLs.