Third Crystalline Form of P(NDI2OD-T2) with Pronounced End-on Texture

We report the observation of a third crystalline polymorph, form III, of the well-studied electron-transporting conjugated polymer P(NDI2OD-T2) that exhibits end-on texture. This third polymorph of P(NDI2OD-T2) is distinguished from other polymorphs by having two monomer units incorporated along the backbone-stacking direction, resulting in a doubling of the c axis of the unit cell. Form III crystallites are realized by melt annealing a thin film followed by slow cooling. The distinct packing of this third polymorph is established through the application of grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements combined with peak simulation of candidate unit cells. The discovery of a third polymorph of P(NDI2OD-T2) provides a fresh opportunity for studying structure/function relationships of this important semiconducting polymer.

Automated summary

We report the discovery of a third crystalline polymorph of the electron-transporting conjugated polymer P(NDI2OD-T2), called form III, which exhibits an end-on texture. This new polymorph is characterized by the incorporation of two monomer units along the backbone-stacking direction, resulting in a doubling of the unit cell c axis. The formation of form III crystallites is achieved by melt annealing a thin film followed by slow cooling. Analysis using grazing-incidence wide-angle X-ray scattering (GIWAXS) and peak simulation confirms the unique packing of this polymorph. This discovery presents an exciting opportunity to study the structure/function relationships of this important semiconducting polymer.