Experimental Demonstration of Quasi-resonant Absorption in Silicon Thin Films for Enhanced Solar Light Trapping

We experimentally demonstrate that the addition of partial lattice disorder to a thin-film microcrystalline silicon photonic crystal results in the controlled spectral broadening of its absorption peaks to form quasi resonances: increasing light trapping over a wide bandwidth while also reducing sensitivity to the angle of incident radiation. Accurate finitedifference time-domain simulations are used to design the active-layer photonic crystal so as to maximize the number of its absorption resonances over the broadband interval where microcrystalline silicon is weakly absorbing before lattice disorder augmented with fabrication-induced imperfections is applied to further boost performance. Such a design strategy may find practical use for increasing the efficiency of thin-film silicon photovoltaics.