ABSTRACT
There has been much interest in light-based technologies over the last few decades, leading to a need for high-performance nonlinear optical (NLO) materials. The attractiveness of optical data storage and processing has led to further research in an attempt to fulfill the need for ever faster optical and optoelectrical components. However, implementation of such components has not been perfected and fundamental research into the materials is necessary for this optimization. Potential device applications include electronic devices such as organic light-emitting diodes (OLEDs),
CONTENTS 4.1 Introduction ........................................................................................... 169 4.2 Nonlinear Optical Properties .............................................................. 171 4.3 Size Scaling in Oligomers .....................................................................174 4.4 Nature of Excitations in Conjugated Polymers ................................ 177 4.5 Conformational Disorder and Optical Properties ........................... 178
4.5.1 Conformational Subunits in Conjugated Polymers ............. 179 4.5.2 Coupling to Nuclear Motions ................................................. 181 4.5.3 Exciton-Phonon Coupling and the Role of Torsional
Modes ......................................................................................... 182 4.5.4 Dynamics Following Photoexcitation .................................... 183
4.6 The Three-Pulse Photon Echo Peak Shift Experiment (3PEPS) ..... 186 4.6.1 How the Experiment Works .................................................... 186 4.6.2 Conjugated Polymer Dynamics Studied by 3PEPS .............. 189
4.7 Conclusions ............................................................................................ 194 References ........................................................................................................ 195
photovoltaics, transistors, displays, lasers, sensors, and optical limiters.1-7 The efficiency of such systems depends on the intrinsic optical properties of the materials used as well as photophysical processes such as the formation and decay of excitons upon photoexcitation or after charge combination following electrical carrier injection.
