Highly Conductive P-Type MAPbI(3) Films and Crystals via Sodium Doping

To regulate the optical and electrical properties of the crystals and films of the intrinsic methylammonium lead iodide (CH(3)NH(3)PbI(3)), we dope them with sodium (Na) by selecting sodium iodide (NaI) as a dopant source. The highly conductive p-type sodium-doped CH(3)NH(3)PbI(3) (MAPbI(3): Na) perovskite single crystals and thin films are successfully grown using the inverse temperature crystallization (ITC) method and antisolvent spin-coating (ASC) method, respectively. With the increase of Na(+) doping concentration, the grain size of the film increases, the surface becomes smoother, and the crystallinity improves. Hall effect results demonstrate that both the MAPbI(3): Na thin films and single crystals change their quasi-insulating intrinsic conductivity to a highly conductive p-type conductivity. The room-temperature photoluminescence (PL) peaks of doped MAPbI(3) films slightly blue shift, while the photocarriers' lifetime becomes longer. The optical fingerprints of the doped levels in MAPbI(3): Na perovskites can be identified by temperature-dependent PL. Obvious fingerprints of Na-related acceptor (A(0)X) levels in the doped MAPbI(3): Na were observed at 10 K. These results suggest that sodium doping is an effective way to grow highly conductive p-type MAPbI(3) perovskites.