Organic thin-film polymers have the potential for photovoltaic and flexible electronic applications. However, charge transport is highly sensitive to the mechanical behavior of semi-crystalline semiconducting conjugated polymers, such as blend films of poly(3-hexylthiophene) (P3HT) and a fullerene, phenyl-C61-butyric acid methylester (PCBM). An integrated computational and experimental approach is used to identify the dominant microstructural characateristics at different physical scales that would affect both the mechanical behavior and strength and electrical properties of P3HT/PCBM thin films. The computational finite-element approach is based on a recently developed microstructural approach that represents the polymer microstructure as a four-phase model that is physically representative of crystalline domains, an amorphous interphase, tie-chain bridging regions, and PCBM particles. The crystalline phase is modeled with dislocation-density based crystalline plasticity, the amorphous interphase is modeled as a viscoplastic region, the inter-aggregate tie chains are modeled with finite elasticity, and the fullerene are modeled with a finite-elasticity approach that accounts for the high strength carbon (C-C) bonds. The experimental approach combines polymer thin film mechanics and optoelectronic device measurements along with detailed morphological characterization of how cracks can form in the thin films. Based on this approach, the fundamental effects of intralamella crystalline disorders, amorphous chain entanglements, and P3HT edge-on and face-on interfacial orientations can be used to provide new insights between mechanical and electrical behavior.