Polaronic transport on conductive metal-organic frameworks from first principles

Hybrid organic-inorganic materials are an emerging class of functional materials with important technological applications in solar energy conversion, catalysis and carbon capture. Among these, metal–organic frameworks (MOFs) correspond to three-dimensional porous materials with potential applications in batteries and fuel cells. Recent studies have shown that polarons, localized quasi-particles formed by excess electronic charge and its self-induced local lattice distortion, play an important role in the transport and optoelectronic properties of electrically conductive MOFs; and therefore, in their overall performance in real devices. In this work, we revisit recent experimental results [1,2] and use theoretical and computational first principles methods to investigate the structural stability and electronic properties of electron polarons, as well as their transport properties. We describe our theoretical results for two specific hybrid organic-inorganic materials: the metallic doped system K_xFe₂(BDP)₃ (0 < x < 2; BDP^2- = 1,4-benzenedipyrazolate) [1], and the two-dimensional ferrimagnetic and conductive system CrCl₂(pyz)₂ (pyz = pyrazine) [2]. References: [1] Aubrey et al., Nature Materials 17, 625 (2018); [2] Pedersen et al., Nature Chemistry 10, 1056 (2018).