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

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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.