Weng Zhichao, Gillin William P, Kreouzis Theo
Materials Research Institute and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, E1 4NS, London, United Kingdom.
Sci Rep. 2019 Mar 5;9(1):3439. doi: 10.1038/s41598-019-40132-5.
The Polaron Pair (PP) model has been successfully applied to magnetoconductance (MC) in organic semiconductor devices under ultra-small magnetic fields (USMFE). We report µT resolution MC measurements carried out with high sensitivity (better than 10) on the common organic semiconductor tris-(8-hydroxyquinoline)aluminium in the range ±500 µT displaying clear minima at ~±240 µT. Unlike traditional approaches, where device MC is simply evaluated using the PP model using nominal parameters for microscopic quantities such as the local hyperfine magnetic field, we have carried out actual fitting of the PP MC model to the experimentally obtained data. The fitting procedure yields physically realistic values for the polaron pair decay rate, local hyperfine magnetic field and triplet contribution to dissociation namely: [Formula: see text] = 28.6 ± 9.7 MHz, [Formula: see text] = 0.34 ± 0.04 mT and [Formula: see text] = 0.99 ± 0.01 respectively. The local hyperfine field obtained by fitting is in excellent agreement with independently calculated values for this system and is reproducible across different devices and independent of drive conditions. This demonstrates the applicability of the fitting approach to any organic USMFE MC data for obtaining microscopic parameter values.
极化子对（PP）模型已成功应用于超小磁场（USMFE）下有机半导体器件的磁电导（MC）。我们报告了在±500 μT范围内对常见有机半导体三（8 - 羟基喹啉）铝进行的具有高灵敏度（优于10）的μT分辨率MC测量，在约±240 μT处显示出明显的最小值。与传统方法不同，传统方法是使用PP模型简单地使用诸如局部超精细磁场等微观量的标称参数来评估器件MC，而我们已将PP MC模型实际拟合到实验获得的数据。拟合过程得出了极化子对衰减率、局部超精细磁场和三重态对解离贡献的符合物理实际的值，即：[公式：见文本] = 28.6 ± 9.7 MHz，[公式：见文本] = 0.34 ± 0.04 mT和[公式：见文本] = 0.99 ± 0.01。通过拟合得到的局部超精细场与该系统独立计算的值非常吻合，并且在不同器件上可重现且与驱动条件无关。这证明了拟合方法对于获取微观参数值的任何有机USMFE MC数据的适用性。
