Improving the order of crystalline regions of poly(3-hexylthiophene) by crystallization from the self-nucleation domains

•Crystallization from the self-nucleation domain leads to an improved crystalline structure.•Well-set self-nucleation and crystallization temperatures are required for ordering process.•Isothermal annealing increases the crystallinity significantly.•Isothermal annealing moderately improves the crystalline quality.