Valence fluctuations of Fe2+ and Fe3+ were studied in a solid solution of LixFePO4 by nuclear resonant forward scattering of synchrotron x rays while the sample was heated in a diamond-anvil pressure cell. The spectra acquired at different temperatures and pressures were analyzed for the frequencies of valence changes using the Blume-Tjon model of a system with a fluctuating Hamiltonian. These ...

Abstract Organic–inorganic hybrid perovskites manifest unique photophysical properties in terms of their long carrier lifetime, low recombination rate, and high defect tolerance, enabling them to be promising candidates optoelectronic devices. However, such advanced are unexpected perovskite materials with moderate charge mobility. Recent investigations have revealed that these appealing were e...

Time- and wavelength-resolved pump-probe measurements are performed on the conductive, primary and secondary doped, forms of polyaniline in solution to investigate the relaxation dynamics of photoexcited polarons. Contrasting dynamics observed in the two forms allow investigation of electronic (and structural) relaxation of this material. Pump pulse at 800 nm photoexcites an electron from the v...

The optical absorption of a many (continuum) polaron gas is derived in the framework of a variational approach at zero temperature and weak or intermediate electron-phonon coupling strength. We derive a compact formula for the optical conductivity of the many-polaron system taking into account many-body effects in the electron or hole system. Within the method presented here, these effects are ...

The retarded Green’s function G(k, ω) of a single small spin polaron in the three-band model for the CuO2 plane is calculated in the self-consistent Born approximation. It is shown that such a spin polaron is a good quasiparticle excitation for realistic values of spin exchange J and effective hopping τ . The polaron spectral density Ap(k, ω) demonstrates small damping in contrast to the result...

On examining the stability of a Wigner crystal in an ionic dielectric, two competitive effects due to the polaron formation are found to be important: (i) the screening of the Coulomb force 1/εsr, which destabilizes the crystal, compensated by (ii) the increase of the carrier mass (polaron mass). The competition between the two effects is carefully studied, and the quantum melting of the polaro...

Low-dimensional perovskites offer a rare opportunity to investigate lattice dynamics and charge carrier behavior in bulk quantum-confined solids, in addition to them being the leading materials in optoelectronic applications. In particular, zero-dimensional (0D) inorganic perovskites of the Cs4PbX6 (X = Cl, Br, or I) kind have crystal structures with isolated lead halide octahedra [PbX6]4- surr...

Measurements of conductivity and thermopower as a function of oxygen fugacity (fO2) are used to derive a model for conduction in olivine. Thermopower at 1000– 1200◦C is between 50 and 400 μV/K and has a positive fO2 dependence, and electrical conductivity exhibits approximately a /11 power dependence on fO2 . However, small polarons, considered to be the conducting defect in olivine at these te...

The motion of an electron in a polar crystal has often been treated in a number of previous works motivated by its increasing interest in transport phenomena in semiconductors, which play an important role in the miniaturization of electronic devices. In addition to its possible connection with the real behavior of an electron and a crystal, this model represents one of the simplest examples of...

Recently, much effort has been devoted to improve the efficiency of organic photovoltaic solar cells based on blends of donors and acceptors molecules in bulk heterojunction architecture. One of the major losses in organic photovoltaic devices has been recombination of polaron pairs at the donor-acceptor domain interfaces. Here, we present a novel method to suppress polaron pair recombination a...