Intrinsic point defects in lead-free organic inorganic hybrid double perovskite (OIHDP) (MA)2KBiCl6

Organic Inorganic Hybrid Double Perovskite (OIHDP) (MA)2KBiCl6 is an alternative material greatly potential for CH3NH3PbCl3. We have made a report of the narrow and long pentahedral region of (MA)2KBiCl6, which is stably according to chemically potential calculation by the first principles method. It is also found that a deep acceptor defect VMA could be easily formed in such kind of (MA)2KBiCl6, leading to the tendency of intrinsic p-type conductivity. A deep donor defect BiMA is obviously suppressed under a Cl-rich growth environment, and a deep acceptor defect ClMA is more likely to be produced with Cl-poor conditions. These results indicate that an increased abundance of Cl elements is going firmly with a reduced generation of BiMA, while the subsequent situation is that defects in ClMA are easier to be made than those in VMA. A great richness of Cl is necessary for an achieved effect of the inhibited deep defect BiMA, only through which the degraded photoelectric performance caused by deep defects could be avoided. Moreover, combination with the former experimental results, we found that the richness of Cl (halide ion) is necessary for an achieved good performance of solar cell devices.