Heat Transfer Enhancement of n-Type Organic Semiconductors by an Insulator Blend Approach

The transfer of heat energy in organic semiconductors (OSCs) plays an important role in advancing the applications of organic electronics, especially for lifetime issues. However, compared with crystalline inorganic semiconductors, the thermal transport of OSCs is less efficient and a relevant understanding is very limited. In this contribution, we show that the heat conduction of OSCs can be enhanced by blending with a "commodity" insulator (both thermal and electrical). PC₇₁BM, a well-known electron transporter but poor thermal conductor, was selected as the host OSC material. The blending of a small amount of polystyrene (PS), a commonly used insulating polymer, can facilitate the heat transfer of PC₇₁BM films, as substantiated by the scanning photothermal deflection technique and an infrared thermal camera. The phase thermodynamics of PC₇₁BM/PS blends indicates that the efficient heat transfer preferably occurs in the OSC/insulator blends with better intimate mixing, where isolated PC₇₁BM domains can be effectively bridged by PS that thread through the regions. The applicability of this approach can be observed in blends with another host material-ITIC. This work provides a facile strategy for designing thermally durable organic electronic devices.