Long-range exciton transport in organic semiconductors is essential for the performance of optoelectronic devices. However, solution-processed π-conjugated polymers films typically exhibit short exciton diffusion lengths (2 s-1. Notably, the maximum value of exciton diffusion lengths and diffusion coefficient can reach up to approximately 396 nm and 0.63 cm2 s-1, respectively. Well-ordered hierarchical structure with an outstanding chain alignment in spherulite provides a uniform excitonic energy landscape, enabling ultralong exciton diffusion. The reduced defect density in the spherulite film may result in shallower trap states, facilitating exciton diffusion and radiative recombination. Polymer light-emitting diodes based on submillimeter-scale spherulite films exhibit deep-blue electroluminescence with high brightness (4897 cd m-2) at low current density and good color purity. These findings demonstrate that the long-range ordered spherulite structure can significantly enhance the excitons transport and improve the overall optoelectronic property.
Sun et al. (Wed,) studied this question.