Back Mirror‐Free Selective Light Absorbers for Thermoelectric Applications

Abstract Improving light absorption is essential for the development of solar thermoelectric generators. Most efficient light absorbers require a back mirror (a thick metal film) to reduce the reflectivity by promoting the interference between the incident and the reflected light. However, the presence of thick a continuous metal film supposes a limitation for thermoelectric applications, as it behaves like a shortcut of the Seebeck voltage. In this work, a back mirror‐free selective light absorber is presented, designed for the fabrication of thermoelectric devices. The combination of a high and a low refractive index material covered by a semi‐transparent electrode is optimized. As a difference to the back mirror, the semi‐transparent electrode can be patterned to prevent the quenching of the Seebeck voltage. Thanks to this, the low refractive index material can be replaced by a transparent thermoelectric, enabling efficient heat‐to‐energy conversion with negligible loss of absorption performance.