Imaging the diffusion of photoexcited free charge carriers in organic-inorganic trihalide perovskites




Wannlund, David Grant

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Organic-inorganic perovskites have recently attracted significant attention because of their large - and increasing - power conversion efficiencies (PCEs) reaching upwards of 20%. With the promise of application in photovoltaics and optoelectronics, Methylammonium Lead Triiodide (MAPbI₃), one such organic-inorganic trihalide perovskite, warrants further investigation of the carrier dynamics at the nanoscale level. After introducing organic-inorganic trihalide perovskites in Chapter 1, I discuss the construction and design challenges of the new Cryochamber Light Assisted Microwave Impedance Microscope (L-MIM) in Chapter 2. In Chapter 3, using the recently constructed Cryochamber L-MIM, I spatially map the intrinsic photoconductivity of MAPbI₃ with nanoscale resolution to reveal diffusion lengths below 10μm independent of the incident laser power density. I demonstrate the utility of L-MIM in revealing nanoscale electronic properties of emerging materials and discuss future applications of this powerful tool in Chapter 4.



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