Synergistic Effect of Hybrid CdSe Nanobelt/PbI2 Flake Heterojunction Toward Drastic Performance Flexible Photodetectors

In-Situ High-Performance Photodetectors Based on CdSe Nanobelts Decorated with CuI Nanocrystals

Photodetectors with high responsivity are crucial elements in various modern industrial applications. CdSe nanobelts, due to their direct bandgap, have emerged as a high-performance material with wide-ranging applications in photodetector technology. For CdSe nanobelt-based photodetectors, which already exhibit broad applicability, enhancing their performance is a key area of ongoing research and development. In this study, we report the successful synthesis of CdSe nanobelt photodetectors decorated with CuI nanocrystals through a combination of physical vapor deposition and a poly(vinyl alcohol) film transfer process. This approach significantly improves the performance of the photodetectors. In the 405-765 nm range with fixed light intensity, the responsivity and external quantum efficiency of the CuI@CdSe photodetectors peaked at 242.88 A/W and 579.18%, 11.6 times higher than those of the in-situ CdSe photodetectors. At 520 nm with 0.94 mW/cm2 intensity, these metrics reached 289.53 A/W and 860.727%, about 38.645 times higher than those of the in-situ CdSe photodetectors. To further demonstrate the enhanced performance, we prepared an image signal transmission system to validate the optical imaging capabilities of the photodetectors. The CuI@CdSe photodetectors successfully converted a preset image into the final output image with a resolution of 110 × 93 pixels, showcasing their potential for practical imaging applications. This work significantly boosts the responsivity and external quantum efficiency of CdSe photodetectors through the incorporation of CuI nanocrystals. It also paves the way toward creating advanced high-performance photodetectors of the future.

Van der Waals Schottky Junction Photodetector with Ultrahigh Rectifying Ratio and Switchable Photocurrent Generation

Metal-semiconductor junctions play an important role in the development of electronic and optoelectronic devices. A Schottky junction photodetector based on two-dimensional (2D) materials is promising for self-powered photodetection with fast response speed and large signal-to-noise ratio. However, it usually suffers from an uncontrolled Schottky barrier due to the Fermi level pinning effect arising from the interface states. In this work, all-2D Schottky junctions with near-ideal Fermi level depinning are realized, attributed to the high-quality interface between 2D semimetals and semiconductors. We further demonstrate asymmetric diodes based on multilayer graphene/MoS2/PtSe2 with a current rectification ratio exceeding 105 and an ideality factor of 1.2. Scanning photocurrent mapping shows that the photocurrent generation mechanism in the heterostructure switches from photovoltaic effect to photogating effect at varying drain biases, indicating both energy conversion and optical sensing are realized in a single device. In the photovoltaic mode, the photodetector is self-powered with a response time smaller than 100 μs under the illumination of a 405 nm laser. In the photogating mode, the photodetector exhibits a high responsivity up to 460 A/W originating from a high photogain. Finally, the photodetector is employed for single-pixel imaging, demonstrating its high-contrast photodetection ability. This work provides insight into the development of high-performance self-powered photodetectors based on 2D Schottky junctions.

Artificial Intelligence Meets Flexible Sensors: Emerging Smart Flexible Sensing Systems Driven by Machine Learning and Artificial Synapses

The recent wave of the artificial intelligence (AI) revolution has aroused unprecedented interest in the intelligentialize of human society. As an essential component that bridges the physical world and digital signals, flexible sensors are evolving from a single sensing element to a smarter system, which is capable of highly efficient acquisition, analysis, and even perception of vast, multifaceted data. While challenging from a manual perspective, the development of intelligent flexible sensing has been remarkably facilitated owing to the rapid advances of brain-inspired AI innovations from both the algorithm (machine learning) and the framework (artificial synapses) level. This review presents the recent progress of the emerging AI-driven, intelligent flexible sensing systems. The basic concept of machine learning and artificial synapses are introduced. The new enabling features induced by the fusion of AI and flexible sensing are comprehensively reviewed, which significantly advances the applications such as flexible sensory systems, soft/humanoid robotics, and human activity monitoring. As two of the most profound innovations in the twenty-first century, the deep incorporation of flexible sensing and AI technology holds tremendous potential for creating a smarter world for human beings.