Characterization of the internal parameters of nanostructured light induced thermionic emission devices for energy conversion

We propose a method to calculate the output current-voltage characteristics of a light induced thermionic emission device. This approach improves on the existing methods by having both a higher precision and higher range in evaluating the associated integrals, resulting in simulated device characteristics with a wider range of parameters. This method represents a significant step towards the characterization of emergent devices due to the unknowns involved in their internal parameters. More importantly, its high numerical precision and flexibility allow one to solve the reverse problem and evaluate the internal parameters of the device such as workfunction, from experimental current-voltage curves. As an experimental case, a carbon nanotube forest was used as the emitter of a thermionic device and locally heated to about 2,000 K using a 50-mW focused laser light. The current-voltage characteristics were measured and fitted to simulation data to obtain the internal parameters of the device. The obtained parameters were consistent with the values obtained with other methods. The estimation of these parameters was previously not feasible with one single type of experiment.