Ultralong-range exciton transport in submillimeter-scale spherulite film of π-conjugated polymers

Lili Sun^a, Chen Sun^b

^aSchool of Flexible Electronics (SoFE) & State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, 66 Gongchang Road, Shenzhen 518107, China

^bDongguan Key Laboratory of Micro-Nano Optical Field Manipulation and Sensing, School of Physical Sciences, Great Bay University, Dongguan 523000, China

Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)

B4 Photophysics of organic semiconductors

Barcelona, Spain, 2026 March 23rd - 27th

Organizers: Safakath Karuthedath and Jafar Khan

Poster, Lili Sun, 977
Publication date: 15th December 2025

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 (< 20 nm) due to local imperfections or variations in interchain packing. Here, large-area submillimeter-scale spherulites are achieved by treating the spin-coated polydiarylfluorene film under solvent vapor annealing. The exciton diffusion length, visualized using transient photoluminescence microscopy, is determined to be an average of 186 nm, with a

corresponding diffusion coefficient of 0.14 cm²s^-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.

References:

[1] Sun, L., Yuan, Y., Xu, Y. et al. Ultralong-range exciton transport in submillimeter-scale spherulite film of π-conjugated polymers. Nat Commun (2026).

Acknowledgements:

L. Sun acknowledge support from the China Postdoctoral Science Foundation under Grant Number 2024M753737 and Shenzhen Science and Technology Program (Grant No. RCBS20231211090610014)

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