Numerical study of InGaN tandem solar cells with intermediate bands.

Theoretical investigations of InGaN tandem solar cells with intermediate bands (IBs) have been conducted through calculating the diode equation taking into account the radiative and nonradiative recombination currents. The calculated maximum efficiencies of the double-junction cell with one IB in each subcell are 57.85% and 68.37% under AM1.5G one-sun and 46000-sun illuminations, respectively. It has also been observed that the combined device with the top-cell bandgaps of 2.9-3.4 eV (2.6-3.4 eV for full concentration) may have an opportunity to realize the application of over 50% efficiency. We suggest that the optimized width of the IB layer be designed in the range of 1-6 μm if its absorption coefficient is 104-105 cm-1 in the IB region. [ABSTRACT FROM AUTHOR]