From the Diode Array U.S. Patent #3,890,161:
Diode arrays absorb energy out of the air as heat, cooling their surroundings, while they make available a matching amount of electrical power. The intermediary, bridging both forms of energy, is Johnson noise? where heat causes the motion of electrical carriers in electronic components. When Johnson noise occurs in diodes, asymmetrical conductivity supports more electron flow internally from the cathode to the anode making the anode the negative side of an intermittent direct current electrical circuit. The electrical power produced and heat absorbed is increased by aggregating many diodes together in consistent alignment parallel or, because the voltage is low, parallel series.
Modern nanotechnology? can fabricate billions of diodes per square centimeter resulting in such a high power density that carrying the heat in and conducting the electricity out are engineering challenges.
A microcircuit prototype demonstrated scientific feasibility by producing somewhat more than ½ kTB watts of power in 1993. That was so long ago that corroborating experiments would be useful. The modern 1T7 chip from Virginia Diodes Inc is suitable. They are easily annoyed by unconventional uses of their products so relations should be highly businesslike.