Department of Math and Physics, North Carolina Central University , Durham, North Carolina 27707, United States.
Department of Physics and Engineering Physics, Tulane University , New Orleans, Louisiana 70118, United States.
Nano Lett. 2017 Oct 11;17(10):6056-6061. doi: 10.1021/acs.nanolett.7b02471. Epub 2017 Sep 11.
We perform the transient absorption spectroscopy experiments to investigate the dynamics of the low-energy collective electron-hole excitations in α-copper phthalocyanine thin films. The results are interpreted in terms of the third-order nonlinear polarization response function. It is found that, initially excited in the molecular plane, the intramolecular Frenkel exciton polarization reorients with time to align along the molecular chain direction to form coupled Frenkel-charge-transfer exciton states, the eigenstates of the one-dimensional periodic molecular lattice. The process pinpoints the direction of the charge separation in α-copper phthalocyanine and similar organic molecular structures. Being able to observe and monitor such processes is important both for understanding the physical principles of organic thin film solar energy conversion device operation and for the development of organic optoelectronics in general.
我们进行了瞬态吸收光谱实验，以研究α-铜酞菁薄膜中低能集体电子-空穴激发的动力学。结果根据三阶非线性极化响应函数进行了解释。结果发现，最初在分子平面中激发的分子内 Frenkel 激子极化随时间重新取向，沿分子链方向排列，形成耦合的 Frenkel-电荷转移激子态，这是一维周期性分子晶格的本征态。这一过程确定了α-铜酞菁和类似有机分子结构中电荷分离的方向。能够观察和监测这样的过程，对于理解有机薄膜太阳能转换器件的工作物理原理以及有机光电学的发展都非常重要。
