ure , suggests that non-radiative recombination processes, particularly defect-assisted non-radiative recombination and recombination with dark carriers, dominate the decay response. This is reinforced by the fact that the excitation densities (ca. 10 12 to 10 14 photons cm -2 ) are substantially higher than the calculated carrier density (10 16 cm -3 or 10 12 cm -2 for a 1 µm absorption length), indicating that defect-mediated recombination plays a key role in limiting carrier lifetimes. So, while formation of a "defect-ordered" structure likely suppresses spontaneous hole generation, it may also lead to rapid non-radiative recombination pathways of photogenerated carriers.