Holographic gratings were recorded in ${\mathrm{C}}_{60}$ -doped nematic liquid crystals (NLCs) by two-beam coupling. The asymmetric energy transfer dependence on the polarity of the applied voltage and multiple diffractions in two-beam coupling indicated that the gratings were photorefractive and worked in the Raman–Nath regime. The diffraction efficiencies (DEs) of the main diffraction orders were investigated at different applied voltages. The diffractive intensity distribution was asymmetric, and a first-order DE as high as 66% (as high as 84% excluding the influence of the scattering) was obtained from the $20\mathrm{\mu m}$ thick ${\mathrm{C}}_{60}$ -doped NLC film.