Jijun Qiu

Limitations in heteroepitaxial growth and material property modulation present a formidable challenge for the development of near-infrared-midwave infrared (NIR-MIR) dual-band uncooled detectors capable of operating in both quantum communication and thermal analysis applications. Leveraging our proposed substrate surface selenization technique, we demonstrate a PbSe/Ge/Si heterostructure enabling response at NIR and MIR. The device achieves a room-temperature responsivity of 0.43 A·W^-1 at 2700 nm and 0.7 A·W^-1 at 1550 nm under laser illumination. Blackbody testing reveals peak detectivities (D*) of 4.2 × 10⁹ cm·Hz^1/2·W^-1 at 3.7 μm and 3.5 × 10⁹ cm·Hz^1/2·W^-1 at 1.2 μm. Additionally, the theoretically optimized structure shows that a back-to-back n-i-p-i-n architecture could elevate D* to 2.0 × 10¹⁰ cm·Hz^1/2·W^-1 and 9.8 × 10¹⁰ cm·Hz^1/2·W^-1 at MIR and NIR, respectively. This architecture represents a promising step toward compact multispectral systems with room-temperature dual-band sensitivity, which are of interest for field-deployable quantum communication terminals and portable thermal analytics.

IV–VI/Ge heteroepitaxy provides a solution for the epitaxial incompatibility between IV–VI semiconductors and silicon-based read-out integrated circuits (Si-ROICs).

The long-term operational stability of perovskite solar cells (PSCs) is governed by a complex interplay of multiple coupled degradation mechanisms rather than isolated factors. Key processes including organic cation decomposition, halide anion oxidation, and ion migration do not occur independently but synergistically interact, ultimately leading to progressive lattice degradation and irreversible device failure. In this study, we propose a “fluorinated hydrogen-bond armor” strategy to comprehensively safeguard formamidinium cations (FA⁺) against deprotonation, shield iodide (I⁻) from oxidation, and suppress ion migration. 6-Fluoro-lH-benzimidazole-2-thiol (F-MBI) forms a stabilized complex with FA⁺ through hydrogen bonding. The strongly electronegative fluorine substituent induces local electronic redistribution via a hydrogen-bond-mediated electronic bridge, passivating proton-active sites and mitigating FA⁺ deprotonation. Simultaneously, the thiol (–SH) group in F-MBI acts as a reducing agent, protecting I from oxidative degradation. Moreover, F-MBI homogenizes the vertical concentration distribution of Cs⁺ and FA⁺ within the perovskite, eliminating the concentration gradient that drives ion migration. The F-MBI modified PSCs achieved an outstanding power conversion efficiency (PCE) of 26.51% (stabilized PCE of 25.85%) and retained over 90% of their initial efficiency after continuous maximum power point tracking (MPP) for 1950 hours under the ISOS-L-2 protocol. Furthermore, the incorporation of F-MBI into the fabrication of large-area modules (active area = 64.68 cm²) yielded an impressive PCE of 20.99%, highlighting the broad applicability and scalability. Our work lays a solid scientific foundation for the comprehensive enhancement of perovskite device photostability and the accelerated advancement toward commercialization.

One-dimensional semiconductor nanowires (NWs) are natural polarization photodetectors, thanks to their optical absorption anisotropy and efficient electrical transport channels. However, ultrathin NWs beyond practical fabrication capabilities are often required to achieve the desired polarization sensitivity. Here, we demonstrate a configuration of planar arrayed core-shell NW architectures with substantially enhanced absorption dichroism for linearly polarized light. The high polarization ratio originates from synergistic effect of three rational designs: a NW core consisting of indirect-bandgap semiconductor as light-trapping cavity, a thin shell of photosensitive material as light absorber, and arrayed photonic structure for optical interference. By employing all-inorganic halide perovskites, these NW arrays exhibit a dichroic ratio up to 110.5 without the need for ultrathin NWs. The core-shell NW architecture is experimentally feasible and offers insights into design of high-sensitivity polarization photodetectors using optical resonance.

A new p⁺pBn⁺ barrier infrared detector was designed via MBE technology, significantly reducing the room temperature dark current and enhancing the detectivity, which provides a promising solution for next-generation uncooled MWIR detectors.

Anion exchange in halide perovskites offers prospective approaches to band gap engineering for miniaturized and integrated optoelectronic devices. However, the band engineering at the nanoscale is uncontrollable due to the rapid and random exchange nature in the liquid or gas phase. Here, we report a source-limiting mechanism in solid-state anion exchange between low-dimensional perovskites, which readily gives access to ultralong compositional gradient nanowires (NWs) with lengths of up to 100 μm. The exchanged NWs remain single-crystalline with intact morphology, while the halogen content exhibits an apparent gradient distribution, leading to a tapered energy band profile along a NW. In the dynamic study of anion behavior, it is shown that the spatial stoichiometric composition can be precisely tuned following Fick's law of diffusion. In addition, self-powered, spectrally resolved photodetectors incorporating multiple detection units within a single gradient NW are demonstrated. This work provides a feasible strategy for the realization of perovskite-based ultracompact optoelectronics, imaging sensors, and other miniaturized semiconductor devices.