Detailed balance analysis of photovoltaic materials and devices

The recent years have seen amazing progress in various photovoltaic technologies, like new world records for Cu(In, Ga)Se
²
, Si, and GaAs solar cells or the unprecedented rise of organo-metal halide materials. Furthermore, new nano-electronic and nano-photonic concepts claim to challenge traditional limits like the Shockley-Queisser-limit for the maximum power conversion efficiency or the Yablonovitch-limit for the maximum light path enhancement. In the light of the recent developments, it appears necessary to revisit fundamental theories in order to extend the description of limiting cases towards a consistent top-down approach based on detailed balance. Such an approach allows one to quantify departures from the ideal situation as well us to judge whether or not proposed concepts can really deliver what they promise. The present contribution proposes a method that allows us to measure the prospects of materials and devices with direct relation to the thermodynamic limits. The method applies to the direct experimental analysis of materials as well as to the quantification of theoretical material prospects from first principle calculations. In this way, we gain by simple experiments figures of merit for both the electrical and the optical quality of materials and devices.