  For highly interested organolead perovskite based solar cells, the
photoproducts are regarded as the co-existed exciton and free carriers. In this
study, we carefully re-examined this conclusion with our recently developed
density-resolved spectroscopic method. Heat-annealing related two photoproduct
systems are observed. We found that the widely accepted model is only true for
single crystal and freshly made films without heat-annealing. For those
sufficiently heat-annealed films, another system presenting significant
emissive exciton-carrier collision (ECC) is discovered. In addition, the
appearing of ECC indicates the emerging of an internal morphology after heat
annealing, which is assigned to a recently discussed twinning subgrain
structure. We proved that such subgrain structures broadly exist in perovskite
films. This finding could prove the morphological basis for high performance of
perovskite working layers.
