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

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Intrinsic methylammonium lead iodide (CH3NH3PbI3) exhibits quasi-insulating properties.
• Controlling the optical and electrical characteristics of perovskite materials is crucial for advanced applications.

Purpose of the Study:

• To investigate the effect of sodium (Na) doping on the properties of methylammonium lead iodide (CH3NH3PbI3).
• To develop a method for producing highly conductive p-type CH3NH3PbI3 perovskite single crystals and thin films.

Main Methods:

• Sodium doping using sodium iodide (NaI) as the dopant source.
• Growth of CH3NH3PbI3: Na single crystals via inverse temperature crystallization (ITC).
• Fabrication of CH3NH3PbI3: Na thin films using antisolvent spin-coating (ASC).

Main Results:

• Successfully synthesized highly conductive p-type sodium-doped CH3NH3PbI3 (MAPbI3: Na) crystals and films.
• Increased Na+ doping concentration led to larger grain size, smoother surfaces, and improved crystallinity.
• Hall effect measurements confirmed the transition to p-type conductivity.
• Room-temperature photoluminescence showed a slight blue shift, and photocarrier lifetime increased.
• Temperature-dependent photoluminescence identified Na-related acceptor levels (A0X) at 10 K.

Conclusions:

• Sodium doping is an effective strategy for achieving highly conductive p-type CH3NH3PbI3 perovskites.
• The doping process enhances crystal quality and modifies optoelectrical properties.
• The observed optical fingerprints confirm the incorporation of sodium and the formation of specific energy levels.