Tu H, Mogyorosi K, Kelley D F
University of California-Merced, Merced, CA 95344, USA.
J Chem Phys. 2005 Jan 22;122(4):44709. doi: 10.1063/1.1835892.
Time-resolved and static spectroscopic results on GaSe nanoparticle aggregates are presented to elucidate the exciton relaxation and diffusion dynamics. These results are obtained in room-temperature TOP/TOPO solutions at various concentrations. The aggregate absorption spectra are interpreted in terms of electrostatic coupling and covalent interactions between particles. The spectra at various concentrations may then be interpreted in terms of aggregate distributions calculated from a simple equilibrium model. These distributions are used to interpret concentration-dependent emission anisotropy kinetics and time-dependent emission spectral shifts. The emission spectra are reconstructed from the static emission spectra and decay kinetics obtained at a range of wavelengths. The results indicate that the aggregate z axis persistence length is about 9 particles. The results also show that the one-dimensional exciton diffusion coefficient is excitation wavelength dependent and has a value of about 2 x 10(-5) cm(2)/s following 406 nm excitation. Although exciton diffusion results in very little energy relaxation, subsequent hopping of trapped electron/hole pairs occurs by a Forster mechanism and strongly red shifts the emission spectrum.
本文展示了关于GaSe纳米颗粒聚集体的时间分辨和静态光谱结果，以阐明激子弛豫和扩散动力学。这些结果是在室温下不同浓度的TOP/TOPO溶液中获得的。聚集体吸收光谱通过颗粒间的静电耦合和共价相互作用来解释。然后，不同浓度下的光谱可以根据从简单平衡模型计算出的聚集体分布来解释。这些分布用于解释浓度依赖性发射各向异性动力学和时间依赖性发射光谱位移。发射光谱是根据在一系列波长下获得的静态发射光谱和衰减动力学重建的。结果表明，聚集体z轴持久长度约为9个颗粒。结果还表明，一维激子扩散系数与激发波长有关，在406nm激发后，其值约为2×10(-5) cm(2)/s。尽管激子扩散导致的能量弛豫非常少，但随后被俘获的电子/空穴对通过福斯特机制发生跳跃，并使发射光谱强烈红移。
