School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, PR China.
Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Nanoscale. 2016 Jul 7;8(27):13228-35. doi: 10.1039/c5nr07893h.
Organic/inorganic heterojunction photoanodes are appealing for making concurrent use of the highly photoactive organic semiconductors, and the efficient dielectric screening provided by their inorganic counterparts. In the present work, organic/inorganic nanotube heterojunction arrays composed of TiO2 nanotube arrays and a semiconducting N,N-(dicyclohexyl) perylene-3,4,9,10-tetracarboxylic diimide (PDi) layer were fabricated for photoelectrochemical water splitting. In this arrayed architecture, a PDi layer with a tunable thickness was coated on anodic TiO2 nanotube arrays by physical vapor deposition, which is advantageous for the formation of a uniform layer and an adequate interface contact between PDi and TiO2. The obtained PDi/TiO2 junction exhibited broadened visible light absorption, and an effective interface for enhanced photogenerated electron-hole separation, which is supported by the reduced charge transfer resistance and prolonged excitation lifetime via impedance spectroscopy analysis and fluorescence emission decay investigations. Consequently, such a heterojunction photoanode was photoresponsive to a wide visible light region of 400-600 nm, and thus demonstrated a highly enhanced photocurrent density at 1.23 V vs. a reversible hydrogen electrode. Additionally, the durability of such a photoanode can be guaranteed after long-time illumination because of the geometrical restraint imposed by the PDi aggregates. These results pave the way to discover new organic/inorganic assemblies for high-performance photoelectric applications and device integration.
有机/无机异质结光阳极吸引人之处在于可以同时利用高活性的有机半导体和其无机对应物提供的高效介电屏蔽。在本工作中，制备了由 TiO2 纳米管阵列和半导体 N,N-（二环己基）苝-3,4,9,10-四羧酸二酰亚胺（PDi）层组成的有机/无机纳米管异质结阵列，用于光电化学水分解。在这种排列结构中，通过物理气相沉积在阳极 TiO2 纳米管阵列上涂覆了具有可调厚度的 PDi 层，这有利于形成均匀的层和 PDi 与 TiO2 之间的充分界面接触。所得的 PDi/TiO2 结表现出宽的可见光吸收，并具有增强的光生电子-空穴分离的有效界面，这通过阻抗谱分析和荧光发射衰减研究得到了支持，表明电荷转移电阻降低和激发寿命延长。因此，这种异质结光阳极对 400-600nm 的宽可见光区域具有光响应性，因此在 1.23V 相对于可逆氢电极时表现出高增强的光电流密度。此外，由于 PDi 聚集体施加的几何约束，这种光阳极在长时间光照后可以保证其耐用性。这些结果为发现用于高性能光电应用和器件集成的新型有机/无机组件铺平了道路。
