Complex Dynamics of Photo-Switchable Guest Molecules in All-Optical Poling Close to the Glass Transition: Kinetic Monte Carlo Modeling

• DOI: 10.1021/acs.jpcb.7b11949
• Publication Date: 2018-01-16T02:32:08Z
• Authors: W. Radosz; G. Pawlik; A. C. Mitus
• Keywords: Kinetic Monte Carlo; Matrix (chemical analysis); Density matrix; Poling; Stochastic matrix

We study theoretically the kinetics of noninteracting photoswitchable guest molecules (model azo-dye) dispersed at low concentration in host polymer matrix) all-optical poling process close to glass transition temperature Tg. modify kinetic Monte Carlo model used our previous studies nonlinear optical processes host-guest systems. The matrix is simulated using bond-fluctuation model. multiple trans-cis-trans cycles formulated terms probabilities which depend on local free volume and its dynamics. Close Tg, buildup polar order, monitored angular probability density functions, follows a power-law time while evolution susceptibilities related second harmonic generation effect stretched-exponential law. This complex dynamics implies presence dynamic heterogeneities space spread complexity from otherwise simple molecules. A qualitative physical picture mosaic-like states-intertwined areas free- hindered motion molecules-is proposed role short longer scales for promotion discussed. brief comparison theory available experimental data given.