Perovskite-Perovskite Homojunctions via Compositional Doping

Area of Science:

• Materials Science
• Solid-State Physics
• Semiconductor Research

Background:

• Semiconductor electronic properties are controllable via doping.
• Hybrid metal halide perovskites show great potential, but doping remains underdeveloped.
• Perovskite-perovskite homojunctions have not been previously reported.

Purpose of the Study:

• To create and characterize the first perovskite-perovskite homojunction.
• To demonstrate controllable doping in methylammonium lead iodide (MAPI) thin films.
• To explore the feasibility of using these homojunctions in electronic devices.

Main Methods:

• Vacuum deposition of stoichiometrically tuned methylammonium lead iodide (MAPI) films.
• Adjusting the relative deposition rates of methylammonium iodide (MAI) and lead iodide (PbI2) to achieve p-type (MAI excess) and n-type (MAI defect) doping.
• Infrared spectroscopy to confirm stoichiometry and methylammonium content.
• Cross-sectional scanning Kelvin probe microscopy (SKPM) to analyze the junction.

Main Results:

• Successfully fabricated a perovskite-perovskite homojunction using MAPI.
• Achieved p-type and n-type doping by precise control of film stoichiometry.
• Confirmed stoichiometry changes using infrared spectroscopy.
• Measured a 250 mV contact potential difference (CPD) across the junction using SKPM.

Conclusions:

• Demonstrated a novel method for creating perovskite-perovskite homojunctions.
• Showcased the potential for tunable doping in MAPI thin films.
• The developed homojunctions are feasible for implementation in electronic devices, such as planar diodes.