Molecular trap engineering enables superior high-temperature charge–discharge efficiency in a polymer blend with densely packed molecular chains†

Abstract

Polymer dielectrics are ideal for capacitors in power electronics, power conditioning, and pulsed power systems due to their high breakdown strength, ease of processing, and reliability. However, they currently fall short of the high-temperature requirements for emerging applications such as hybrid and electric vehicles and photovoltaic power generation. Here, we present a general approach to impeding charge transport in all-organic polymer composites by introducing organic molecular semiconductors with high electron affinity into a polymer blend with densely packed molecular chains. This strategy significantly reduces conduction loss and enhances breakdown strength under elevated temperatures and high electric fields. At 150 °C, the resulting polymer blend-based all-organic composites achieve high discharged energy densities of 3.45 J cm⁻³ and 3.68 J cm⁻³ for TPI/PEI/PC61BM and TPI/PEI/NTCDA composites, respectively, with a 90% charge–discharge efficiency. This performance is approximately three times higher than that of the pristine TPI/PEI blend (1.19 J cm⁻³). NTCDA, in particular, demonstrates similar effectiveness in enhancing high-temperature capacitor performance while being significantly more cost-effective compared to PC61BM and other previously reported organic molecular semiconductors. Consequently, this polymer blend-based all-organic composite offers a promising solution for the scalable fabrication of high-performance, high-quality polymer films required for high-temperature capacitive energy storage.