Excitons and Polarons in Luminiscent Conjugated Polymers. A Flash-Photolysis and211 Pulse-Radiolysis Study

摘要

The interest of scientists in molecules containing carbon-carbon pi bonds can be211u001etraced back to the early twentieth century. At that time there was a very large 211u001edemand for new dyes. In analogy with beta-carotene, the orange pigment found in 211u001ecarrots, the chemists of the day synthesized small conjugated molecules, i.e. 211u001emolecules with a bonding structure of alternating double and single carbon-carbon 211u001ebonds. As the A-electrons in the conjugated system are less tightly bonded to the 211u001ecarbon nuclei compared to delta-electrons, the A-electron require less energy to 211u001ebe perturbed into excited states. As a result molecules containing a number of 211u001econjugated repeat units absorb light in the visible part of the electromagnetic 211u001espectrum, with the energy of the absorption maximum decreasing with the number of 211u001erepeat units.