School of Materials Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700032, India.
Chem Asian J. 2019 Dec 13;14(24):4681-4687. doi: 10.1002/asia.201900905. Epub 2019 Sep 10.
Considering the importance of conjugated polymer nanoparticles, major emphasis has been given for designing and understanding the energy transfer and charge transfer processes of organic-inorganic hybrids for light harvesting applications. In the present study, we have designed an aqueous solution-based light harvesting system using conjugated polymer nanoparticles (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], MEH-PPV) and Au nanoparticles. The change in photo-induced processes in the presence of metal nanoparticles are studied by steady-state absorption, time-resolved emission, time-resolved fluorescence up-conversion, ultrafast anisotropy and femtosecond transient absorption spectroscopy. Global and target analysis of transient absorption data validate the creation of a collective delocalized state in polymer nanoparticles, and the time scale for excitation energy funnelling from S state to low lying collective delocalized state (CL ) is 18 ps. Then, the electron transfer from the CL state to Au NP occurs with a time constant of 150 ps. The 815 ps long lived charge transfer (CT) state signifies the charge transfer from the CL state of polymer nanoparticles to Au NP. Such basic understanding of relaxation processes in hybrid systems is very important for designing inorganic-organic hybrid light-harvesting systems.
考虑到共轭聚合物纳米粒子的重要性，人们主要致力于设计和理解用于光收集应用的有机-无机杂化材料中的能量转移和电荷转移过程。在本研究中，我们使用共轭聚合物纳米粒子（聚[2-甲氧基-5-（2-乙基己氧基）-1,4-亚苯基乙烯]，MEH-PPV）和金纳米粒子设计了一种基于水溶液的光收集系统。通过稳态吸收、时间分辨发射、时间分辨荧光上转换、超快各向异性和飞秒瞬态吸收光谱研究了金属纳米粒子存在下光诱导过程的变化。瞬态吸收数据的全局和目标分析验证了聚合物纳米粒子中集体离域态的产生，并且激发能从 S 态到低能集体离域态（CL）的能量传递时间尺度为 18 ps。然后，从 CL 态到 Au NP 的电子转移以 150 ps 的时间常数发生。815 ps 长寿命的电荷转移（CT）态表示从聚合物纳米粒子的 CL 态到 Au NP 的电荷转移。这种对混合系统中弛豫过程的基本理解对于设计无机-有机杂化光收集系统非常重要。
