Thermodynamic Mechanism Governing the Coalescence of Conductive Particles in PEDOT:PSS under Laser Irradiation

The strategy of obtaining selective electrical properties by laser irradiation of poly(3,4-ethylenedioxythiophene) stabilized with poly(4-styrenesulfonate) (PEDOT:PSS) is breaking new ground in the fabrication process of conductive films. In this study, the theoretical mechanism by which the laser irradiation induces coalescence of PEDOT-rich particles and improves electrical properties of PEDOT:PSS was explored from a thermodynamic perspective. The microstructural evolution by laser irradiation was experimentally verified, and the equivalent environment was implemented from coarse-grained molecular dynamics simulations. The results suggest that selective disruption between pi-pi interactions and electrostatic attraction, the forces governing the PEDOT-rich domain, is a key driving factor for enhanced phase separation in PEDOT:PSS. The energy supplied from the laser provides sufficient molecular mobility to allow the PEDOT-rich core to integrate with other adjacent cores without compromising the strong internal cohesion of its own core. The enhanced mobility leads to bridging-generating events with triggering of active molecular rearrangements between the cores, driving the coalescence of conductive particles.