Bi2S3量子点敏化TiO2纳米阵列结构的制备及光电性能研究

利用水热法制备一维TiO₂纳米棒阵列,并采用化学浴沉积法(CBD)结合自组装技术在TiO₂纳米棒上敏化Bi₂S₃量子点,形成TiO₂/Bi₂S₃复合纳米棒阵列.系统研究了复合结构的表面形貌、晶体结构、光学及光电性能.结果表明:在修饰有三氨丙基三乙氧基硅烷自组装单分子膜(APTS-SAMs)的TiO₂纳米棒表面形成一层致密的Bi₂S₃量子点敏化层,这一技术的关键是含-NH₂末端的APTS-SAMs可有效促进Bi₂S₃的异相成核作用;Bi₂S₃的沉积时间对复合结构的光吸收及光电响应性能有决定性的影响,薄膜的光电流随着沉积时间呈先增加后减小的趋势,在沉积时间为20 min时,光电流密度最大.这是因为随着沉积时间的增加,TiO₂纳米棒表面Bi₂S₃量子点密度增大,光吸收增加;而当沉积时间进一步延长时,Bi₂S₃在TiO₂纳米棒表面的大量负载而形成堆积和团聚,导致表面缺陷增多,光生电子复合几率增大,从而使光电流密度减小.

Preparation and Photoelectrical Properties of Bi2S3 Quantum Dots Sensitized TiO2 Nanorod-Arrays

Hydrothermally synthesized TiO₂ nanorod arrays on FTO glass substrates were functionalized with uniform Bi₂S₃ quantum dots by CBD method combined with self-assembled monolayers(SAMs). The surface morphology, structure, optical and photoelectrochemical behaviors of the TiO₂/Bi₂S₃ nanorod arrays are considered. The results that uniform Bi₂S₃ thin films were deposited on the surface of TiO₂ nanorods modified by APTS SAMs. The key of the technology is that the APTS SAM possessing -NH₂ functional groups can be employed to control nucleation. Moreover, the deposition time of Bi₂S₃ thin film plays a key role in the visible light absorption as well as photoelectric response of TiO₂/Bi₂S₃ nanorod arrays. It reveals that, with the increase of the deposition time, the J_sc of composite thin film first increased and then decreased, and a J_sc maximum value of 0.13 mA·cm^-2 reached at 20 min deposition of Bi₂S₃. The increase of J_sc for the initial deposition time could be interpreted as the result of enhanced absorption in the visible light range. Further increase the deposition time resulted in an obvious decrease in Jsc. This phenomenon might be attributed to Bi₂S₃ overloading on the surface of TiO₂ resulted in aggregations and conglomerations, leading to more surface defects and recombination of photoexcited carrier.