Solid State Research: Perovskites

Abstract to Poster presented at Molecular Foundry

We investigate temperature-dependent transport behavior of photogenerated free carriers and excitons in single-crystal methylammonium lead bromide (MAPbBr3) nanostructures via scanning photocurrent microscopy (SPCM), photocurrent spectroscopy, and spectrally and temporally resolved photoluminescence (TRPL) measurements. While SPCM profiles show a rapid decay of the photocurrent in about 3μm at room temperature as the photoexcitation moves away from the contact. A much longer decay profile becomes significant at temperatures below 220K with rapid recombination near the electrodes. Remarkably, the long decay photocurrent shows a carrier diffusion length of over 110μm, along the nanosecond-scale lifetimes observed in TRPL indicates incredibly large carrier mobility at lower temperatures.  We hypothesize that this kind of long-distance transport is mainly excitonic due to their dipolar, therefore charge-neutral nature. The poster for this project can be found here.

Skills Acquired:

• Work with a Wire Bonder from West Bond

• Photocurrent Microscopy Measurements

  • Scanning Photocurrent Microscopy (SPCM)

  • Circular Photogalvanic Effect measurement  (CPGE)

• Analysis  with MESUX programming 

• Analysis with IGOR programming 

• Atomic Force Microscopy (AFM)

Research Emphasis — Perovskite Optoelectronic Materials:

Core Skills:
Perovskite Synthesis, Scanning Photocurrent Microscopy (SPCM), Circular Photogalvanic Effect (CPGE), Crystal Growth, Semiconductor Doping, Optoelectronic Characterization, Materials Analysis

Conducted research on methylammonium halide perovskite single crystals (MAPbI3 and MAPbBr3), focusing on the relationship between crystal composition, doping behavior, and charge-carrier transport properties. Performed Scanning Photocurrent Microscopy (SPCM) and Circular Photogalvanic Effect (CPGE) measurements to analyze photocurrent response and carrier diffusion behavior in engineered perovskite systems.

Developed and optimized synthesis routes to tailor semiconductor properties, including efforts to transition materials from p-type toward n-type behavior to improve charge-carrier diffusion lengths and photocurrent performance. Additionally, led synthesis development of inorganic and hybrid perovskite crystals including CsPbBr3 and FAPbBr3 for advanced optoelectronic characterization.

Advisor:

Dr. Dong Yu: yu@physics.ucdavis.edu