Studies of emerging photovoltaics, such as organic and perovskite solar cells, have recently shown that the separation of photo-generated charge carriers is correlated with non-thermal, coherent oscillations within the illuminated device. We consider this experimental evidence in light of results from the theory of open quantum systems that point to the need for a self-oscillating internal capacitor, acting as a microscopic piston, in order to explain how an illuminated solar cell operates as an autonomous heat engine, capable of extracting electrical work from the thermal disequilibrium between the solar radiation and the material at room temperature. Based both on general thermodynamic considerations and on the accumulated experimental evidence, we propose a dynamic picture of work extraction by photovoltaic devices that supersedes the quasi-static descriptions prevalent in the literature. Finally, we argue that such a dialogue between condensed matter physics and quantum thermodynamics may offer a guide for the design of new energy transducers.
This is work done in collaboration with theorists Robert Alicki (Gdansk) and David Gelbwaser-Klimovsky (MIT), as well as experimentalist Elizabeth von Hauff (VU Amsterdam).