Transparent conducting oxides as selective filters in thermophotovoltaic devices

Transparent conducting oxides (TCOs) are evaluated as selective filters in thermophotovoltaic (TPV) devices using theoretical considerations. The TCOs plasma frequency and the optical properties in the near infrared are calculated using the Drude theory for free carriers. To improve the radiation transmission for energies higher than the band gap of the cells and the reflection back to the emitter for sub-band gap radiation the TCO's optical properties are studied as a function of electron concentration. Taking into account the photocell and emitter spectral response radiation, the optimal free carrier concentration and the thus thickness of the TCO to be used as selective filter are calculated.