arXiv subjects

Vladimir Bruevich

Publications and source records attributed to Vladimir Bruevich.

4 recordsLinked to original sources

arXiv2026

Nonequilibrium transport in epitaxial CsPbBr3 single crystals

Transport of optically excited carriers in semiconductors is typically described within a quasi-equilibrium picture, where energy is carried by a single thermalized quasiparticle population characterized by well-defined transport coefficients. Here, we demonstrate that in epitaxial CsPbBr3 perovskite single crystals, this picture holds near room temperature - but breaks down dramatically at low temperature. Using transient microscopy, we show that optically measured carrier mobilities match device-scale Hall-effect and field-effect transistor measurements across a broad temperature range, resolving reported discrepancies and validating the equilibrium framework in the free-carrier regime. Below ~60 K, however, when excitonic effects become significant, equilibrium models begin to fail. We observe two coupled populations: a transient (<100 ps) hot-exciton gas with a diffusivity ~25-30 cm 2 /s - greatly exceeding the diffusivity expected for thermalized excitons - and a quasi-localized state that is fed by the cooling of the hot-exciton gas. These results reveal that in CsPbBr3, transport and thermalization are not separable processes: carriers move while still redistributing among internal degrees of freedom, breaking the timescale separation that underpins equilibrium transport theory in conventional semiconductors. By resolving transport at the population level, we can directly access the competing kinetics of exciton formation, interconversion, and cooling, offering a new space for controlling energy flow in perovskite materials and their photonic applications.

cond-mat.mes-hall↗

arXiv2026

Electrostatic Photoluminescence Tuning in All-Solid-State Perovskite Transistors

We demonstrate an all solid state semiconductor device, based on epitaxial single crystalline metal halide perovskites, enabling reversible control of a perovskite photoluminescence with a gate voltage. Fundamentally distinct from electroluminescent diodes, such a photoluminescence field effect transistor uses the gate electric field to electrostatically modulate the interfacial density of mobile charges, thereby affecting the radiative and nonradiative recombination channels of photocarriers. Varying the gate voltage in such transistors efficiently changes the rate of nonradiative interfacial recombination and modulates the photoluminescence intensity by 65 to 98 percent (depending on temperature). At favorable gating, nearly complete elimination of non-radiative losses can be achieved. This functionality, coupled with the strong visible-range absorption and emission, possible due to the high absorption coefficient, as well as controllable thickness and macroscopically homogeneous morphology of epitaxial perovskite films, leads to high external photoluminescence quantum efficiencies realized in large-area, thin-film devices. Such high-efficiency, scalable, electrostatically tunable optoelectronic switches broaden the potential applications of metal-halide perovskites in photonics and optoelectronics.

cond-mat.mtrl-sci↗

arXiv2026

Atomic-Scale Surface Imaging of bulk Epitaxial CsPbBr3 Perovskite Single Crystals on Mica using Light Assisted Scanning Tunneling Microscopy at Low-Temperature (80 K)

Epitaxial single-crystalline CsPbBr3 perovskite films on mica, prepared ex-situ, are explored using a low-temperature scanning tunneling microscope (STM) by probing the unoccupied electronic states of their surface in ultra-high vacuum (UHV) at 80 K. Light-assisted STM measurements under a broadband illumination with visible light were employed to enhance and stabilize surface conductivity. STM imaging across the surface of macroscopic bulk CsPbBr3 films reveals large flat terraces characterized by a specific type of surface reconstruction, consisting of parallel rows of U-shaped atomic nanostructures. These structures are spaced by 12 angstroms and exhibit an internal periodicity of 5.1 angstroms. Density functional theory (DFT) calculations reproduce the experimental observations and reveal a competition between different orthorhombic CsPbBr3(110) surface reconstructions: a Cs-rich structure, identified as the most energetically stable, and three alternative PbBr rich reconstructions, which are slightly higher in energy yet remain consistent with the STM data. Additional analyses that explicitly account for the mica substrate exclude the cubic CsPbBr3 phase and other orthorhombic surface orientations, while showing that variations in the mica surface termination do not alter the preferred CsPbBr3(110) reconstruction. This combined approach thereby confirms our assignment and resolves previous STM interpretations of CsPbBr3.

cond-mat.mtrl-sci↗

arXiv2019

Spectroscopic assessment of charge mobility in organic semiconductors

Rapid progress in organic electronics demands new highly efficient organic semiconducting materials. Nevertheless, only few materials have been created so far that show reliable band-like transport with high charge mobilities, which reflects the two main obstacles in the field: the poor understanding of charge transport in organic semiconductors (OSs) and the difficulty of its quantification in devices. Here, we present a spectroscopic method for assessment of the charge transport in organic semiconductors. We show that the intensities of the low-frequency Raman spectrum allow calculation of the dynamic disorder that limits the charge carrier mobility. The spectroscopically evaluated mobility clearly correlates with the device charge mobility reported for various OSs. The proposed spectroscopic method can serve as a powerful tool for a focused search of new materials and highlights the disorder bottleneck in the intrinsic charge transport in high-mobility organic semiconductors.

physics.app-ph↗