All Publications


  • Charge Reservoirs in an Expanded Halide Perovskite Analog: Enhancing High-Pressure Conductivity through Redox-Active Molecules. Angewandte Chemie (International ed. in English) Matheu, R., Ke, F., Breidenbach, A., Wolf, N., Lee, Y., Liu, Z., Leppert, L., Lin, Y., Karunadasa, H. 2022

    Abstract

    As halide perovskites and their derivatives are being developed for numerous optoelectronic applications, controlling their electronic doping remains a fundamental challenge. Herein, we describe a novel strategy of using redox-active organic molecules as stoichiometric electron acceptors. The cavities in the new expanded perovskite analogs (dmpz)[Sn2X6], (X = Br- ( 1Br ) or I- ( 1I )) are occupied by dmpz2+ (N, N'-dimethylpyrazinium), with the LUMOs lying ca. 1 eV above the valence band maximum (VBM). Compressing the metal-halide framework drives up the VBM in 1I relative to the dmpz LUMO. The electronic conductivity increases by a factor of 105 with pressure, reaching 50(17) S cm-1 at 60 GPa, exceeding the high-pressure conductivities of most halide perovskites. This conductivity enhancement is attributed to an increased hole density created by dmpz2+ reduction. This work elevates the role of organic cations in 3D metal-halides, from templating the structure to serving as charge reservoirs for tuning the carrier concentration.

    View details for DOI 10.1002/anie.202202911

    View details for PubMedID 35421260

  • Anomalous Nernst and Seebeck coefficients in epitaxial thin film Co2MnAlxSi1-x and Co2FeAl PHYSICAL REVIEW B Breidenbach, A. T., Yu, H., Peterson, T. A., McFadden, A. P., Peria, W. K., Palmstrom, C. J., Crowell, P. A. 2022; 105 (14)