Abstract
We observed the temperature-dependent real-time lattice parameters and strain exhibited by poly(3-hexylthiophene) crystals in poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) films during thermal annealing in the absence and presence of an Al layer. The strain and relaxed lattice parameters were quantitatively determined. The as-prepared P3HT:PCBM films displayed tensile strain, regardless of the presence of an Al layer. In the absence of an Al layer, the internal strain relaxed at an annealing temperature of 180 °C. In the presence of an Al layer, the strain relaxed, then transitioned to a compressive strain above an annealing temperature of 120 °C.