An optically clear, high strength, high modulus, and high thermal conductivity polyethylene thin film may be formed from a crystallizable polymer and an additive configured to interact with the crystallizable polymer to facilitate crystallite alignment and, in some examples, create a higher crystalline content within the polyethylene thin film. The polyethylene thin film may be characterized by a bimodal molecular weight distribution where the molecular weight of the additive may be less than approximately 5% of the molecular weight of the crystallizable polymer. Example crystallizable polymers may include high molecular weight polyethylene, high density polyethylene, and ultra-high molecular weight polyethylene. Example additives may include low molecular weight polyethylene and polyethylene oligomers. The polyethylene thin film may be characterized by a Young's modulus of at least approximately 10 GPa, a tensile strength of at least approximately 0.7 GPa, and a thermal conductivity of at least approximately 5 W/mK.