RESUMEN
The photoluminescence (PL) of conducting polymer polythiophene (PT) films incorporated with metallophthalocyanines (PcMs) such as CuPc, MgPc, FePc, Li2Pc, and CoPc was studied by PL and time-correlated single photon counting (TCSPC) measurements. Polymer films were prepared by electrochemical polymerization and PcMs migrated into the polymer films by a diffusion method using acetonitrile or toluene as a solvent to dissolve the PcMs. The wavelength of PL emission peaks changed significantly depending on the solvent used in the doping process. Using acetonitrile, the observed PL emission peaks originated from the Q band, whereas they were assigned to the Soret band in the case of toluene. TCSPC measurements showed that PL emission took place through a ligand-ligand transition process when using acetonitrile because the average lifetimes were comparable and independent of the central metal ions for CoPc-, Li2Pc-, and MgPc-doped polymer films. Conversely, using toluene, it was found that ligand-ligand emission occurred for Li2Pc-, MgPc-, and FePc-doped films. To identify the cause of the drastic change in PL emission pattern, x-ray photoelectron spectroscopy measurements were obtained. A lower binding energy component appeared in the C 1s core-level spectra of acetonitrile-processed PcM-doped PT films, whereas this component shifted to higher energy and overlapped with the main peak for toluene-processed PcM-doped PT films. The lower binding energy component corresponded to photoelectrons due to the C atoms in the benzene rings of the ligand. Lower binding energy components also appeared in the N 1s core-level spectra of acetonitrile-processed PcM-doped PT films, and this component shifted to higher energy for toluene-processed PcM-doped PT films. These lower energy components were assigned to the core-level peaks due to the N atoms at the meso position bridging between pyrrole rings. This suggests that the electron charge at the N sites of the meso positions in toluene-processed films was smaller than in acetonitrile-processed ones. The changes in energy at benzene C sites and meso N sites suggest that the electronic states of the phthalocyanine in the toluene-processed films were porphyrin-like, so the Soret band became dominant in the PL emission spectrum.
RESUMEN
The authors conducted polyaniline (HA) polymerization on a micro-scale patterned Si water and nano-scale patterned Al surface. Polymerization was performed using a microliter solution droplet made of aniline, HCI and oxidation agent ammonium peroxodisulfate (APS). The droplet was dropped on a flat Si wafer, a micro-patterned Si wafer and a nanostructured Al surface. The SEM image showed that PA was densely polymerized on the circle edge of the dropped 1 mm sized droplet on the flat Si wafer because of large surface tension due to the flat surface. On the other hand, a droplet was broken on a circular trench pattern of 100 µm in diameter fabricated on a Si wafer. The width and depth of the trench were 1 µm and 1 µm, respectively. Tree-like polymer was intensively polymerized along the circular trench. Droplet was also dropped on a lattice trench pattern whose pitch was 10 µm. The width and the depth of the trench were 1 µm and 1 µm, respectively. The SEM image showed that dots of PA were fabricated along the trenches. Far smaller dots of PA were also observed on the flat area of the lattice. Thus, micro-scale structure affects the shape and size of PA in polymerization. Nanoscopic polymerization of PA was conducted locally in a nanoscale highly-oriented line pattern with nanoscale trenches formed on an Al surface. One of the characteristic fabricated patterns was a highly conductive PA line pattern whose pitch was 100 nm. In this case, point-contact IV characteristic measurement, step-like curve was observed. PL spectra of the PA line-pattern exhibited significantly enhanced emission peaks at 380, 450 anc 550 nm due to PA which were overlapped by the rippled PL pattern due to the Al nanostructure.