arXiv subjects

Ruitian Chen

Publications and source records attributed to Ruitian Chen.

4 recordsLinked to original sources

arXiv2026

Wavelength-dependent photo-creep in halide perovskite single crystals

Halide perovskites are promising optoelectronic materials, but their time-dependent permanent deformation under illumination (i.e., photo-creep) is poorly understood, limiting their mechanical stability. Here we report wavelength-dependent photo-creep phenomena in CsPbBr3 and FAPbBr3 single crystals, studied by constant-load nanoindentation under controlled light with various wavelengths. Compared with creep in dark, continuous green light (near-bandgap) suppresses creep by 19% in CsPbBr3 and 10% in FAPbBr3, whereas violet (far above-bandgap) light enhances creep by 16% in CsPbBr3 and 8% in FAPbBr3. In contrast, when light is onset during creep, blue light enhances creep most prominently, whereas green light exhibits minimal influence. Such photo-creep behavior in halide perovskites are distinct with photo-plasticity phenomenon in conventional semiconductors. By combining the photoluminescence and photocurrent measurements, we unveil that ion migration promotes dislocation climb and creep, while carrier trapping suppresses dislocation glide and related creep in halide perovskites. Such competition between carrier trapping and ion migration tuned by wavelength governs the photo-creep response. Our findings uncover a photomechanical effect in halide perovskites and highlight how coupled carrier and ion dynamics under illumination affect their device reliability.

cond-mat.mtrl-sci↗

arXiv2025

Unveiling competitions between carrier recombination pathways in semiconductors via mechanical damping

The total rate of carrier recombination in semiconductors has conventionally been expressed using an additive model, r_total = \Sigma r_i , which rules out the interactions between carrier recombination pathways. Here we challenge this paradigm by demonstrating pathway competitions using our newly developed light-induced mechanical absorption spectroscopy (LIMAS), which allows us to probe genuine recombination dynamics in semiconductors via mechanical damping. We show that the total recombination rate in zinc sulfide (ZnS), a model semiconductor material, follows a multiplicative weighting model, r_total \propto \Pi r_i ^(w_i) with \Sigma w_i=1. Under both steady-state and switch-on illuminations, the weighting factors w_i for each recombination pathway-direct, trap-assisted, and sublinear-are dictated by the carrier generation mechanism: (i) interband transition favors direct recombination; (ii) single-defect level-mediated generation promotes trap-assisted recombination; (iii) generation involving multiple saturated defect levels gives rise to sublinear recombination. Upon light switch-off, localized state changes drive a dynamic evolution of w_i, altering pathway competitions. These findings reshape our fundamental understanding of carrier dynamics and provide a new strategy to optimize next-generation optoelectronic devices.

cond-mat.mtrl-sci↗

arXiv2025

Radiation-induced Instability of Organic-Inorganic Halide Perovskite Single Crystals

Organic-inorganic halide perovskites (OIHPs) are promising optoelectronic materials, but their instability under radiation environments restricts their durability and practical applications. Here we employ electron and synchrotron X-ray beams, individually, to investigate the radiation-induced instability of two types of OIHP single crystals (FAPbBr3 and MAPbBr3). Under the electron beam, we observe that 3-point star-style cracks grow on the surface of FAPbBr3, and bricklayer-style cracks are formed on the surface of MAPbBr3. Under the X-ray beam, a new composition without organic components appears in both FAPbBr3 and MAPbBr3. Such cracking and composition changes are attributed to the volatilization of organic components. We propose a volume-strain-based mechanism, in which the energy conversion results from the organic cation loss. Using nanoindentation, we reveal that beam radiations reduce the Youngs modulus and increase the hardness of both OIHPs. This study provides valuable insights into the structural and mechanical stabilities of OIHP single crystals in radiation environments.

cond-mat.mtrl-sci↗

arXiv2024

A survey of energies from pure metals to multi-principal element alloys

In materials science, a wide range of properties of materials are governed by various types of energies, including thermal, physicochemical, structural, and mechanical energies. In 2005, Dr. Frans Spaepen used crystalline face-centered-cubic (fcc) copper as an example to discuss a variety of phenomena that are associated with energies. Inspired by his pioneering work, we broaden our analysis to include a selection of representative pure metals with fcc, hexagonal close-packed (hcp), and body-centered cubic (bcc) structures. Additionally, we extend our comparison to energies between pure metals and equiatomic binary, ternary, and multi-principal element alloys (sometimes also known as high-entropy alloys). Through an extensive collection of data and calculations, we compile energy tables that provide a comprehensive view of how structure and alloying influence the energy profiles of these metals and alloys. We highlight the significant impact of constituent elements on the energies of alloys compared to pure metals and reveal a notable disparity in mechanical energies among materials in fcc-, hcp- and bcc-structured metals and alloys. Furthermore, we discuss the energy relationships, the implications for structural transformations and potential applications, providing insights into the broader context of these energy variations.

cond-mat.mtrl-sci↗