Chaofeng Lü

Cryogenic imaging is essential for applications in space exploration, quantum science, and biomedicine. However, extending cryogenic photodetectors into imaging arrays remains challenging due to the lack of reliable readout mechanisms and effective crosstalk suppression at temperatures below 4 K. Conventional imaging technologies, including charge-coupled devices (CCDs), complementary metal–oxide–semiconductor (CMOS) image sensors, and CMOS-based readout integrated circuits (ROICs), rely on carrier transport and transistor operation that degrade under cryogenic conditions, while superconducting approaches face challenges in scaling and high-speed operation due to wiring complexity and readout constraints. Here, we report a transistor-free, row-column addressable imaging architecture based on graphene-silicon heterojunction arrays, in which the imaging plane consists solely of heterojunction pixels without auxiliary electronic components. Owing to the intrinsic self-blocking effect, the device achieves effective crosstalk suppression and stable imaging at both room temperature (293 K) and cryogenic conditions (3 K). Furthermore, the pronounced suppression of dark current at cryogenic temperatures substantially enhances weak-light sensitivity, enabling imaging at illumination levels nearly 2 orders of magnitude lower than those required at room temperature. This work presents a transistor-free imaging architecture with intrinsic crosstalk suppression, enabling scalable array readout at cryogenic temperatures and providing a promising route toward large-scale, high-density low-temperature imaging.

Flexible photodetectors that combine high photodetection performance with excellent mechanical compliance are highly desirable for emerging applications such as wearable electronics and conformal optoelectronics; however, their realization remains challenging due to the difficulty in integrating high‐quality semiconductor materials with mechanically flexible device architectures. Here, we report an ultrathin flexible graphene‐silicon (GS) heterojunction photodetector enabled by the transfer of a single crystalline silicon membrane from a silicon‐on‐insulator (SOI) wafer onto a polyimide (PI) substrate. A GS Schottky heterojunction formed between graphene and a 2 µm thick silicon membrane serves as the photosensitive unit, while a redesigned top‐contact electrode configuration ensures compatibility with flexible integration. Encapsulated by flexible substrate and encapsulation layers, the device exhibits an overall thickness below 10 µm. The fabricated flexible photodetector exhibits ultra‐low dark current, stable reverse bias operation, a wide linear dynamic range (LDR) of ∼120 dB under 660 nm, broadband spectral responsivity spanning from the visible to the near infrared region, sub‐microsecond temporal response, and low noise characteristics. This work provides an effective strategy for integrating high‐quality single‐crystalline silicon with graphene to realize ultrathin, high‐performance flexible photodetectors, offering a promising platform for future flexible optoelectronic applications.

Electrochemical batteries currently serve as the primary power source for a wide range of daily applications, yet they present substantial risks to human health and environmental sustainability. Drawing inspiration from clockwork springs and carbon nanoscrolls, this work proposes a planar spiral structure (PSS) using 2D materials (graphene, MoS₂, diamane) for mechanical energy storage, offering an eco-friendly alternative to conventional electrochemical systems. Molecular dynamics simulations reveal that elastic torsional deformation of the PSS occurs in two stages, including a delamination-wrapping process driven by bending strain and van der Waals interactions, followed by tensile deformation. Energy storage predominantly arises from the first stage, where strain energy increases almost linearly with rotation angle. A theoretical model is developed, correlating strain energy with torsional angle and quantifying contributions from bending and surface energy. Simulations show that materials with higher bending stiffness exhibit superior energy storage capacity due to dominant bending strain energy. The model validates that diamane PSS can achieve a high energy storage capacity, with bending energy governing its entire delamination-wrapping process. This work provides a low-carbon design for nanoscale energy storage, applicable to biomedical micro/nanodevices, and establishes a framework for optimizing 2D nanomaterial-based spiral architectures.

Flexible imagers play fundamental roles in electronic eyes, biomedical monitoring, robotics, and satellite technologies, while crosstalk‐free multiplexing of large pixel arrays remains a bottleneck. Two popular ways to mitigate crosstalk require external components — passive matrices with blocking diodes and active matrices with phototransistors/active backplanes, which increase fabrication complexity, reduce fill factor, and limit mechanical adaptability. These limitations are overcome by a flexible imager based on a self‐blocking graphene–silicon heterojunction array. This intrinsic self‐blocking mechanism enables crosstalk‐free row–column readout with a minimalist imaging‐plane architecture comprising only photosensitive area and orthogonally patterned electrodes. This simple two‐terminal pixel structure achieves a high fill factor of 36% and a pixel density of 42 PPI and is readily scalable to large‐deformation stretchable configurations. Individual pixels exhibit high stability, broadband sensitivity from ultraviolet to near‐infrared, an ultrafast 80‐ns rise time, and a wide linear dynamic range (100 dB under 660 nm). Real‐time imaging with multiple wavelengths (532 nm, 1064 nm) and dynamically varying curvatures is demonstrated using FPGA‐based readout. By coupling structural simplicity with high performance, this work establishes a generalizable platform for self‐blocking metal–semiconductor optoelectronics, offering new routes toward scalable, mechanically adaptive, and crosstalk‐free imaging systems relevant to emerging angstrom‐thick 2D metals.