Toward an efficient extremely thin absorber solar cell based on ZnO nanowire arrays

In this contribution, the absorption and electrical transport mechanisms are investigated as key elements for predicting the photoconversion efficiency of core shell ZnO CdTe nanowire based solar cells. It is shown that the absorption of the optimized morphological dimensions originates from the combination of individual nanowire effects and arrangement effects. Individual nanowire effects, related to the nanowire diameter are revealed by the large absorption of an optical key mode in the long wavelength regime. The nanowire arrangement effects, related to the period of the array, occur at short wavelengths, through diffraction processes. The ZnO CdTe nanowire arrays were grown on top of FTO/glass substrate in order to study the electrical transport mechanisms. The current-voltage characteristics were measured and simulated for various temperatures. Both the measured and the simulated saturation current show similar variation with temperature, revealing that the transport mechanism in core shell ZnO CdTe nanowire arrays are dominated by trap-assisted tunneling. These findings will be used in optoelectronic simulations, in order to predict the potentialities of the core shell ZnO CdTe nanowire arrays for solar cells.