1. 2 New Materials and Concepts for Cells and Modules
Summary / Abstract:
Hot carrier solar cell principle promises energy conversion efficiency limited by more than 70 % even for very simple structures . Temperature of hot electron gas is the key parameter defining the efficiency of hot carrier solar cells. The problem of strong parasitic flow of thermal energy of electron gas to the phonon gas is not solved so far. The interaction between electron and phonon gases is material specific, so that search for materials or structures with slow cooling rate of the electron gas (e-gas) continues. In order to measure the cooling rate, the solar light is typically replaced by an artificial light source, being a laser. Monochromatic laser radiation is a poor replacement for the spectrally extended sunlight. In most of the experiments, the temperature of the e-gas is measured by assessing either the transient time, or the spectrum of the thermal radiation of the e-gas. In order to decouple the strong optical excitation from rather weak thermal radiation emission, the excitation is done in the pulsed mode. Altogether, the measurement conditions are very different from the conditions in a solar cell. We propose a measurement of carrier temperature by using natural sunlight.