Heutz S, Nogueira A F, Durrant J R, Jones T S
Centre for Electronic Materials and Devices, Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom.
J Phys Chem B. 2005 Jun 16;109(23):11693-6. doi: 10.1021/jp050298l.
The recombination kinetics of photogenerated charge carriers in perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) and copper phthalocyanine (CuPc) thin films grown by organic molecular beam deposition have been studied using transient absorption spectroscopy. Optical excitation is observed to generate long-lived polaron states, which exhibit power law recombination dynamics on time scales from microseconds to milliseconds. Studies as a function of excitation density and temperature, and comparison between heterostructures and PTCDA single layers, all indicate that this power law behavior results from trapping of PTCDA- polarons in localized states, with an estimated trap state density of approximately 6 x 10(17) polarons cm(-3). This recombination behavior is found to be remarkably similar to that previously observed for polymer/fullerene blends, suggesting that it may be generic to a range of semiconducting materials.
利用瞬态吸收光谱研究了通过有机分子束沉积生长的苝-3,4,9,10-四羧酸二酐（PTCDA）和铜酞菁（CuPc）薄膜中光生电荷载流子的复合动力学。观察到光激发产生长寿命的极化子态，其在从微秒到毫秒的时间尺度上呈现幂律复合动力学。作为激发密度和温度的函数进行的研究，以及异质结构与PTCDA单层之间的比较，均表明这种幂律行为源于PTCDA-极化子在局域态中的捕获，估计陷阱态密度约为6×10¹⁷极化子·cm⁻³。发现这种复合行为与先前在聚合物/富勒烯共混物中观察到的行为非常相似，这表明它可能是一系列半导体材料所共有的。
