Creation and annealing of metastable defect states in CH3NH3PbI3 at low temperatures

Methylammonium lead iodide CH3NH3PbI3 , an organic inorganic perovskite widely used for optoelectronic applications, is known to dissociate under illumination with light at photon energies around 2.7 eV and higher. Here, we show that photo induced dissociation is not limited to ambient temperatures but can be observed even at 5K. The photo induced dissociation of N H bonds results in the formation of metastable states. Photoluminescence PL measurements reveal the formation of defect states that are located 100 meV within the bandgap. This is accompanied by a quenching of the band to band PL by one order of magnitude. Defect generation is reversible and annealing at 30K recovers the band to band PL, while the light induced defect states disappear concurrentl