A new concept of ultra-thin film photovoltaic solar cell including a planar photonic crystal is proposed. The goal is to couple the incident light into broad resonances guided in the absorbing layer. To achieve this, a periodic lattice is patterned within the active layer, for example made of holes in amorphous silicon. By adjusting the pattern dimensions, the spectral position and quality factor of these resonances can be controlled so as to optimise the global absorption. Design details will be discussed in this communication.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.