Development of optically detected NMR instrument and its application to π-conjugated polymer devices

本课题的研究目标是开发用于电子激发态材料的光学检测核磁共振光谱仪，并将其应用于π共轭聚合物器件。我们研制了一种能够进行微波场辐照、静态磁场应用和变温实验的光探测磁共振测试夹具。在0 ~ 3.7 mt的静磁场下，对聚（9,9 -二辛基芴）[PFO]和聚（3-烷基噻吩）[P3ATs]等π共轭聚合物的纺涂膜进行了光致发光（PL）测量。典型的光探测磁共振（ODMR）信号是通过与微波场辐照相关的PL强度的微小变化来探测到的。因此，我们使用液晶调制器作为激光功率稳定器，以获得振幅稳定的PL信号。此外，由于大气中的氧气可能会影响π共轭聚合物器件的电子性能，我们尝试使用涡轮分子泵在真空中进行ODMR测量。然而，我们的初步ODMR仪器的灵敏度不足以检测来自聚合物薄膜器件的信号。因此，我们开发了一个用于在约0.3T下测量ODMR的谐振腔，并试图在聚合物器件的ODMR测量中进行电子自旋共振（ESR）测量。在聚合物电子器件方面，我们制作了垂直Au/polymer/Au型随机阈值器件单元，并对Au/polymer/Au元件进行了变温电导率和交流阻抗测量。这种类型的随机阈值装置被认为是神经启发信息处理装置的重要组成部分。

The objective of this research project is to develop optically detected nuclear magnetic resonance spectrometer for materials under electronic excited states, and to apply to π-conjugated polymer devices. We developed a test fixture for optically detected magnetic resonance that was capable of microwave field irradiation, application of static magnetic field, and variable temperature experiments. We succeeded in photoluminescence(PL) measurements for spuncoat membranes of π-conjugated polymers such as poly(9, 9-dioctylfluorene)[PFO] and poly(3-alkylthiophene)s[P3ATs] under static magnetic field of 0-3.7mT.Typical optically detected magnetic resonance (ODMR) signals are detected as small variation of PL intensity in association of microwave field irradiation. Thus, we used laser power stabilizer using a liquid crystal modulator in order to obtain PL signals with stable amplitude. Furthermore, since atmospheric oxygen likely affects on the electronic property of π-conjugated polymer devices, we tried to perform ODMR measurements in vacuo using a turbo molecular pump. However, the sensitivity of our preliminary ODMR instrument was no enough to detect signals from polymer thin film devices. Thus, we developed a resonant cavity for ODMR measurement under ca. 0.3T and attempted to perform electro spin resonance (ESR) measurements in association with ODMR measurements for polymeric devices.As for polymer electronics devices, we fabricated stochastic threshold device unit with the vertical Au/polymer/Au type and carried out variable temperature conductivity and alternating current impedance measurements for Au/polymer/Au elements. This type of the stochastic threshold device is thought of an important element for neuro-inspired information processing device.