Perspective on near-field radiative heat transfer

Although near-field radiative heat transfer was introduced in the 1950s, interest in the field has only recently revived, as the effect promises improved performance in various applications where contactless temperature regulation in the small-scale is a requirement. With progress in computational electromagnetics as well as in nanoinstrumentation, it has become possible to simulate the effect in complex configurations and to measure it with high precision. In this Perspective, we highlight key theoretical and experimental advances in the field, and we discuss important developments in tailoring and enhancing near-field thermal emission and heat transfer. We discuss opportunities in heat-to-electricity energy conversion with thermophotovoltaic systems, as well as non-reciprocal heat transfer, as two of many recent focus topics in the field. Finally, we highlight key experimental challenges and opportunities with emerging materials, for probing near-field heat transfer for relevant technologies in the large-scale.