Reply to 'On the thermodynamics of light trapping in solar cells'

We are grateful to Rau and Kirchartz for their thoughtful remarks on our Commentary, and hope this dialog will generate clarity in the physics of high-efficiency photovoltaics. Our Commentary identified several new design approaches and architectures using photonic structures to increase photovoltaic efficiency. It was driven by thinking about the design of solar cells with (i) high radiative efficiency, (ii) 1 sun unconcentrated (C = 1) operation and (iii) employing a light-collimating angle restrictor element (as opposed to a geometrical concentrator).