Bio

Following undergraduate studies and postgraduate research in the United Kingdom, using synchrotron radiation to study the crystalline structures of semiconductors for solar energy applications, Kieran's work at Stanford now focusses on using related diffraction techniques on an ultra-fast timescale to study ion hopping in solid electrolytes for all solid-state batteries.

Professional Education

  • PhD, University of Cambridge, Physics (2024)
  • MChem, University of Oxford, Chemistry (2019)

Stanford Advisors

Contact

  • Academic
    kwporr@stanford.edu
    University - Scholar Department: Materials Science and Engineering Position: Postdoctoral Scholar

Additional Info

Links

Current Research and Scholarly Interests

Kieran’s current research focuses on improving solid-state electrolytes for batteries and fuel cells. Key challenges for these technologies include replacing the harmful and flammable liquid electrolytes currently used as industry standards and achieving fast charging to improve commercial competitiveness, especially in the transportation sector. Substituting current ion transport media with a highly conductive solid-state electrolyte has the potential to address these challenges, drastically improving energy storage and energy conversion devices. However, the precise mechanism of ion hopping in solids is poorly understood, having been studied primarily from theoretical and computational standpoints. Kieran uses a suite of atomic-scale sensitive real-time structural probes making heavy use SLAC’s X-ray diffraction capabilities to gain a detailed, mechanistic understanding of how ions are transported through solid electrolytes.

Lab Affiliations

All Publications

  • Dynamic nanodomains dictate macroscopic properties in lead halide perovskites. Nature nanotechnology Dubajic, M., Neilson, J. R., Klarbring, J., Liang, X., Bird, S. A., Rule, K. C., Auckett, J. E., Selby, T. A., Tumen-Ulzii, G., Lu, Y., Jung, Y. K., Chosy, C., Wei, Z., Boeije, Y., Zimmermann, M. V., Pusch, A., Gu, L., Jia, X., Wu, Q., Trowbridge, J. C., Mozur, E. M., Minelli, A., Roth, N., Orr, K. W., Mahboubi Soufiani, A., Kahmann, S., Kabakova, I., Ding, J., Wu, T., Conibeer, G. J., Bremner, S. P., Nielsen, M. P., Walsh, A., Stranks, S. D. 2025

    Abstract

    Lead halide perovskites have emerged as promising materials for solar energy conversion and X-ray detection owing to their remarkable optoelectronic properties. However, the microscopic origins of their superior performance remain unclear. Here we show that low-symmetry dynamic nanodomains present in the high-symmetry average cubic phases, whose characteristics are dictated by the A-site cation, govern the macroscopic behaviour. We combine X-ray diffuse scattering, inelastic neutron spectroscopy, hyperspectral photoluminescence microscopy and machine-learning-assisted molecular dynamics simulations to directly correlate local nanoscale dynamics with macroscopic optoelectronic response. Our approach reveals that methylammonium-based perovskites form densely packed, anisotropic dynamic nanodomains with out-of-phase octahedral tilting, whereas formamidinium-based systems develop sparse, isotropic, spherical nanodomains with in-phase tilting, even when crystallography reveals cubic symmetry on average. We demonstrate that these sparsely distributed isotropic nanodomains present in formamidinium-based systems reduce electronic dynamic disorder, resulting in a beneficial optoelectronic response, thereby enhancing the performance of formamidinium-based lead halide perovskite devices. By elucidating the influence of the A-site cation on local dynamic nanodomains, and consequently, on the macroscopic properties, we propose leveraging this relationship to engineer the optoelectronic response of these materials, propelling further advancements in perovskite-based photovoltaics, optoelectronics and X-ray imaging.

    View details for DOI 10.1038/s41565-025-01917-0

    View details for PubMedID 40456909

    View details for PubMedCentralID 10733143

  • Strain Heterogeneity and Extended Defects in Halide Perovskite Devices ACS ENERGY LETTERS Orr, K. P., Diao, J., Dey, K., Hameed, M., Dubajic, M., Gilbert, H. L., Selby, T. A., Zelewski, S. J., Han, Y., Fitzsimmons, M. R., Roose, B., Li, P., Fan, J., Jiang, H., Briscoe, J., Robinson, I. K., Stranks, S. D. 2024; 9 (6): 3001-3011

    Abstract

    Strain is an important property in halide perovskite semiconductors used for optoelectronic applications because of its ability to influence device efficiency and stability. However, descriptions of strain in these materials are generally limited to bulk averages of bare films, which miss important property-determining heterogeneities that occur on the nanoscale and at interfaces in multilayer device stacks. Here, we present three-dimensional nanoscale strain mapping using Bragg coherent diffraction imaging of individual grains in Cs0.1FA0.9Pb(I0.95Br0.05)3 and Cs0.15FA0.85SnI3 (FA = formamidinium) halide perovskite absorbers buried in full solar cell devices. We discover large local strains and striking intragrain and grain-to-grain strain heterogeneity, identifying distinct islands of tensile and compressive strain inside grains. Additionally, we directly image dislocations with surprising regularity in Cs0.15FA0.85SnI3 grains and find evidence for dislocation-induced antiphase boundary formation. Our results shine a rare light on the nanoscale strains in these materials in their technologically relevant device setting.

    View details for DOI 10.1021/acsenergylett.4c00921

    View details for Web of Science ID 001235278400001

    View details for PubMedID 38911532

    View details for PubMedCentralID PMC11190982

  • Composition Dictates Octahedral Tilt and Photostability in Halide Perovskites ADVANCED MATERIALS Iqbal, A. N., Orr, K. P., Nagane, S., Orri, J., Doherty, T. S., Jung, Y., Chiang, Y., Selby, T. A., Lu, Y., Mirabelli, A. J., Baldwin, A., Ooi, Z., Gu, Q., Anaya, M., Stranks, S. D. 2024; 36 (28): e2307508

    Abstract

    Halide perovskites are excellent candidate materials for use in solar cell, LED, and detector devices, in part because their composition can be tuned to achieve ideal optoelectronic properties. Empirical efficiency optimization has led the field toward compositions rich in FA (formamidinium) on the A-site and I on the X-site, with additional small amounts of MA (methylammonium) or Cs A-site cations and Br X-site anions. However, it is not clear how and why the specific compositions of alloyed, that is, mixed component, halide perovskites relate to photo-stability of the materials. Here, this work combines synchrotron grazing incidence wide-angle X-ray scattering, photoluminescence, high-resolution scanning electron diffraction measurements and theoretical modelling to reveal the links between material structure and photostability. Namely, this work finds that increased octahedral titling leads to improved photo-stability that is correlated with lower densities of performance-harming hexagonal polytype impurities. These results uncover the structural signatures underpinning photo-stability and can therefore be used to make targeted changes to halide perovskites, bettering the commercial prospects of technologies based on these materials.

    View details for DOI 10.1002/adma.202307508

    View details for Web of Science ID 001228975000001

    View details for PubMedID 38728063

https://orcid.org/0000-0001-9996-1458