AUTHOR=Li Yujiao , Li Chen , Yu Huanqin , Yuan Beilei , Xu Fan , Wei Haoming , Cao Bingqiang 

TITLE=Highly Conductive P-Type MAPbI3 Films and Crystals via Sodium Doping

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00754

DOI=10.3389/fchem.2020.00754

ISSN=2296-2646

ABSTRACT=<p>To regulate the optical and electrical properties of the crystals and films of the intrinsic methylammonium lead iodide (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>), we dope them with sodium (Na) by selecting sodium iodide (NaI) as a dopant source. The highly conductive p-type sodium-doped CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (MAPbI<sub>3</sub>: 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<sup>+</sup> 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<sub>3</sub>: 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<sub>3</sub> films slightly blue shift, while the photocarriers' lifetime becomes longer. The optical fingerprints of the doped levels in MAPbI<sub>3</sub>: Na perovskites can be identified by temperature-dependent PL. Obvious fingerprints of Na-related acceptor (A<sup>0</sup>X) levels in the doped MAPbI<sub>3</sub>: Na were observed at 10 K. These results suggest that sodium doping is an effective way to grow highly conductive p-type MAPbI<sub>3</sub> perovskites.</p>