Optical nonlinearities and two-photon excited time-resolved luminescence in colloidal quantum-confined CuInS2/ZnS heterostructures
Optical nonlinearities and two-photon excited time-resolved luminescence in colloidal quantum-confined CuInS2/ZnS heterostructures
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DOI：
10.1039/c4ra03154g
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发表时间：
2014-01-01
期刊：
影响因子：
3.9
通讯作者：
Strek, W.
中科院分区：
文献类型：
--
作者：
Cichy, B.;Wawrzynczyk, D.;Strek, W.
本文研究了量子限制三元CuInS 2/ZnS核壳异质结的三阶非线性光学性质和单/双光子激发时间分辨发光的光谱依赖性，并与相应的未包覆CuInS 2核进行了比较.采用Z扫描技术在宽波长范围（550-1500 nm）内测量了量子限制I型核/壳CuInS 2/ZnS及其相应的CuInS 2核的非线性折射和非线性吸收。结果表明，在红色和近红外光谱范围内存在尺寸依赖的双光子吸收带。从CuInS 2核的光学跃迁和宽禁带ZnS壳层的影响两个方面讨论了核/壳CuInS 2/ZnS量子异质结构的立方非线性。利用飞秒时间分辨光致发光谱研究了单/双光子激发态的复合动力学，揭示了电子弛豫的复杂特征。一个通用的统计模型，包括归一化离散分布的衰减率被用于分析的发光衰减曲线。讨论了不同的弛豫路径，包括激子弛豫、施主-受主对复合和自由态-束缚态复合。结果表明，CuInS 2/ZnS和CuInS 2量子点的光学性质非常适合于稳态以及时间分辨的单/多光子荧光技术通常用于生物传感问题。
Comprehensive studies on the spectral dependencies of third-order nonlinear optical properties and one/two-photon excited time-resolved luminescence of quantum-confined ternary CuInS2/ZnS core/shell heterostructures with reference to their corresponding uncoated CuInS2 cores are presented in this work. Nonlinear refraction and nonlinear absorption in the quantum confined type-I core/shell CuInS2/ZnS and their corresponding CuInS2 cores were measured over a wide range of wavelengths (550-1500 nm) using the Z-scan technique. The results revealed the presence of size-dependent two-photon absorption bands in the red and near-infrared spectral range. The cubic nonlinearity of core/shell CuInS2/ZnS quantum heterostructures is discussed in terms of both the CuInS2 core's optical transitions and the impact of the wide-gap ZnS shell layer. Kinetics of recombination of the single/two-photon excited states was investigated with femtosecond time-resolved photoluminescence spectroscopy revealing the complex character of electronic relaxation. A general statistical model involving normalized discrete distribution of decay rates was used for the analysis of luminescence decay curves. Different relaxation paths including the excitonic relaxation, donor-acceptor pair recombination and free-to-bound state recombination are discussed. The results indicate that optical properties of the CuInS2/ZnS and CuInS2 quantum dots are well suited for the steady-state as well as time-resolved single/multiphoton fluorescent techniques utilized commonly for the bio-sensing issues.