Photosensitive Dielectric 2D Perovskite Based Photodetector for Dual Wavelength Demultiplexing

Broadband-Responsive Rubbery Stretchable Vertical-Structured Photodetectors Based on Rubbery Stretchable Transparent Conductors

A rubbery stretchable conductor with high conductivity and transparency is crucial for the development of rubbery stretchable vertical-structured photodetectors. However, the development of such a rubbery conductor is still nascent. Here, we report the scalable manufacturing of rubbery stretchable transparent conductors (RSTCs) and the development of a rubbery stretchable vertical-structured photodetector (RSVPD). The RSTC is fabricated into a specialized micromesh structure by utilizing a close-packed monolayer of polystyrene microspheres as a mask. The micromesh structure not only enhances the conductor's stretchability and transparency but also maintains its conductivity, making it ideal for various applications in stretchable electronics. The RSTCs are used to construct RSVPDs that have high response over a broad spectrum, and their electrical performances can be retained even when subjected to mechanical strains of up to 50%. Furthermore, a stretchable imager based on RSVPD was developed to detect the multipoint light distribution. Lastly, a photoplethysmography (PPG) sensor was also developed for real-time health monitoring.

Wavelength-Controlled Triple-Mode Photoconductance-Polarity-Switching Field Effect Transistor for Secure Time-Variable Encrypted Optical Communication

The controllable polarity switch between positive photoconductance (PPC) and negative photoconductance (NPC) in a photodetector is essential for the realization of versatile, innovative applications. Incorporating polarity-switching photoconductance with other response states, yet still posing challenges, allows for encoding multidimensional distinguishable optical information within a single device, which holds great potential for broadening application scope. Herein, three wavelength-controlled photoresponse modes are present in MoS2-based field effect transistor with lightly doped Si substrate by combining positive/negative photocurrent polarities with slow/fast response speeds. Specifically, a slow PPC response at 520 nm, along with fast bipolar infrared responses (NPC at 980 nm, PPC at 1310 nm), is integrated within a single MoS2 device. The opposite sub-bandgap infrared photoresponses are ascribed to the synergism of the bolometric effect and interfacial photogating, influenced by electrons photogenerated in Si. Based on the triple polarity-switching characteristic of the MoS2 device, the triple-channel real-time secure optical communication system with time-variable encryption algorithms is demonstrated, exponentially increasing the difficulty of brute-force cracking by synchronizing the time-variable key channel with two information channels. This work not only enhances the understanding of sub-bandgap photoresponse mechanisms in 2D material photodetectors but also offers promising avenues for the development of optoelectronics-assisted wireless communication technologies.

Coupling Strategies of Multi-Physical Fields in 2D Materials-Based Photodetectors

2D materials possess exceptional carrier transport properties and mechanical stability despite their ultrathin nature. In this context, the coupling between polarization fields and photoelectric fields has been proposed to modulate the physical properties of 2D materials, including energy band structure, carrier mobility, as well as the dynamic processes of photoinduced carriers. These strategies have led to significant improvements in the performance, functionality, and integration density of 2D materials -based photodetectors. The present review introduces the coupling of photoelectric field with four fundamental polarization fields, delivered from dielectric, piezoelectric, pyroelectric, and ferroelectric effects, focusing on their synergistic coupling mechanisms, distinctive properties, and technological merits in advanced photodetection applications. More importantly, it sheds light on the new path of material synthesis and novel structure design to improve the efficiency of the coupling strategies in photodetectors. Then, research advances on the synergy of multi-polarization effects and photoelectric effect in the domain of bionic photodetectors are highlighted. Finally, the review outlines the future research perspectives of coupling strategies in 2D materials-based photodetectors and proposes potential solutions to address the challenges issues of this area. This comprehensive overview will guide futural fundamental and applied research that capitalizes on coupling strategies for sensitive and intelligent photodetection.

Junction Field-Effect Transistors Based on MoSe2/WSe2 Heterostructures for High-Performance Photodetection

Two-dimensional (2D) materials show great potential in creating high-performance ultracompact photodetectors. Existing 2D photodetectors are usually designed based on a photogating effect or photovoltaic effect. However, achieving a balance between photodetectivity and photoresponsivity presents a significant challenge due to increased dark currents at trap level recombination or the lack of a gain mechanism. Herein, we rationally design a gate-tunable junction field-effect transistor photodetector based on MoSe2 and WSe2. With proper modulating the depletion layer and Schottky barrier using source-drain and gate bias, the device can effectively reduce dark current, resulting in an ultrahigh photodetectivity of 1.55 × 1013 Jones and an ultrahigh optical switching ratio of 104. Furthermore, our photodetector exhibits a high photoresponsivity of 476 A/W and an ultrafast response time of 50 μs under 635 nm laser irradiation with an extended detection capability to the 1550 nm band. These outstanding performances highlight the potential of 2D heterojunctions in addressing the growing demands of next-generation photonic sensors.

Bioinspired single-shot polarization photodetector based on four-directional grating arrays capped perovskite single-crystal thin film

Polarization photodetectors (pol-PDs) have widespread applications in geological remote sensing, machine vision, biological medicine, and so on. However, commercial pol-PDs use bulky and complicated optical systems with lenses, polarizers, and mechanical spools, which are complex and cumbersome, and respond slowly. Inspired by the desert ants' compound eyes, we developed a single-shot pol-PD based on four-directional grating arrays capped perovskite single-crystal thin film without other standard polarization optics. Our pol-PD has a high detectivity, two orders of magnitude greater than that of commercial photodetectors, and exhibits high polarization sensitivity. The high performance of our pol-PD is due to the highly crystalline perovskite single-crystal thin film and regular nanograting structure, made by a nanoimprinting crystallization method. Our single-shot pol-PD is a compact on-chip optoelectronic device that demonstrates excellent performance in a wide range of applications including accurate bionic navigation, sharp image restoration in hazy scenes, stress visualization of polymers, and detection of cancerous areas in tissues without histological staining.

Recent Progress in Photodetectors: From Materials to Structures and Applications

Photodetectors are critical components in a wide range of applications, from imaging and sensing to communications and environmental monitoring. Recent advancements in material science have led to the development of emerging photodetecting materials, such as perovskites, polymers, novel two-dimensional materials, and quantum dots, which offer unique optoelectronic properties and high tunability. This review presents a comprehensive overview of the synthesis methodologies for these cutting-edge materials, highlighting their potential to enhance photodetection performance. Additionally, we explore the design and fabrication of photodetectors with novel structures and physics, emphasizing devices that achieve high figure-of-merit parameters, such as enhanced sensitivity, fast response times, and broad spectral detection. Finally, we discuss the demonstration of new applications enabled by these advanced photodetectors, including flexible and wearable devices, next-generation imaging systems, and environmental sensing technologies. Through this review, we aim to provide insights into the current trends and future directions in the field of photodetection, guiding further research and development in this rapidly evolving area.

Ultrafast Photoexcitation Induced Passivation for Quasi-2D Perovskite Photodetectors

Quasi-2D perovskites exhibit great potential in photodetectors due to their exceptional optoelectronic responsivity and stability, compared to their 3D counterparts. However, the defects are detrimental to the responsivity, response speed, and stability of perovskite photodetectors. Herein, an ultrafast photoexcitation-induced passivation technique is proposed to synergistically reduce the dimensionality at the surface and induce oxygen doping in the bulk, via tuning the photoexcitation intensity. At the optimal photoexcitation level, the excited electrons and holes generate stretching force on the Pb─I bonds at the interlayered [PbI6]-, resulting in low dimensional perovskite formation, and the absorptive oxygen is combined with I vacancies at the same time. These two induced processes synergistically boost the carrier transport and interface contact performance. The most outstanding device exhibits a fast response speed with rise/decay time of 201/627 ns, with a peak responsivity/detectivity of 163 mA W-1/4.52 × 1010 Jones at 325 nm and the enhanced cycling stability. This work suggests the possibility of a new passivation technique for high performance 2D perovskite optoelectronics.

Wide Bandgap Semiconductors for Ultraviolet Photodetectors: Approaches, Applications, and Prospects

Ultraviolet (UV) light, invisible to the human eye, possesses both benefits and risks. To harness its potential, UV photodetectors (PDs) have been engineered. These devices can convert UV photons into detectable signals, such as electrical impulses or visible light, enabling their application in diverse fields like environmental monitoring, healthcare, and aerospace. Wide bandgap semiconductors, with their high-efficiency UV light absorption and stable opto-electronic properties, stand out as ideal materials for UV PDs. This review comprehensively summarizes recent advancements in both traditional and emerging wide bandgap-based UV PDs, highlighting their roles in UV imaging, communication, and alarming. Moreover, it examines methods employed to enhance UV PD performance, delving into the advantages, challenges, and future research prospects in this area. By doing so, this review aims to spark innovation and guide the future development and application of UV PDs.

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

Optoelectronic devices with unconventional form factors, such as flexible and stretchable light-emitting or photoresponsive devices, are core elements for the next-generation human-centric optoelectronics. For instance, these deformable devices can be utilized as closely fitted wearable sensors to acquire precise biosignals that are subsequently uploaded to the cloud for immediate examination and diagnosis, and also can be used for vision systems for human-interactive robotics. Their inception was propelled by breakthroughs in novel optoelectronic material technologies and device blueprinting methodologies, endowing flexibility and mechanical resilience to conventional rigid optoelectronic devices. This paper reviews the advancements in such soft optoelectronic device technologies, honing in on various materials, manufacturing techniques, and device design strategies. We will first highlight the general approaches for flexible and stretchable device fabrication, including the appropriate material selection for the substrate, electrodes, and insulation layers. We will then focus on the materials for flexible and stretchable light-emitting diodes, their device integration strategies, and representative application examples. Next, we will move on to the materials for flexible and stretchable photodetectors, highlighting the state-of-the-art materials and device fabrication methods, followed by their representative application examples. At the end, a brief summary will be given, and the potential challenges for further development of functional devices will be discussed as a conclusion.

High performance photodetector based on CdS/CdS0.42Se0.58nanobelts heterojunction

The ternary alloy CdSxSe1-xcombines the physical properties of CdS and CdSe, and its band gap can be adjusted by changing the element composition. The alloy has charming photoelectric properties as well as potential application value in photoelectric devices. In this work, the CdS/CdS0.42Se0.58nanobelt (NB) heterojunction device was prepared by chemical vapor deposition combined with a typical dry transfer technique. The heterojunction photodetector shows high light switching ratio of 6.79 × 104, large spectral responsivity of 1260 A W-1, high external quantum efficiency of 2.66 × 105% and large detectivity of 7.19 × 1015cm Hz1/2W-1under 590 nm illumination and 3 V bias. Its rise and decay time is about 45/90μs. The performance of the heterojunction photodetector was comparable or even better than that of other CdS(Se) based photodetector device. The results indicate that the CdS/CdS0.42Se0.58NB heterojunction possesses a promising potential application in high performance photodetectors.

Perovskite single-pixel detector for dual-color metasurface imaging recognition in complex environment

Highly efficient multi-dimensional data storage and extraction are two primary ends for the design and fabrication of emerging optical materials. Although metasurfaces show great potential in information storage due to their modulation for different degrees of freedom of light, a compact and efficient detector for relevant multi-dimensional data retrieval is still a challenge, especially in complex environments. Here, we demonstrate a multi-dimensional image storage and retrieval process by using a dual-color metasurface and a double-layer integrated perovskite single-pixel detector (DIP-SPD). Benefitting from the photoelectric response characteristics of the FAPbBr2.4I0.6 and FAPbI3 films and their stacked structure, our filter-free DIP-SPD can accurately reconstruct different colorful images stored in a metasurface within a single-round measurement, even in complex environments with scattering media or strong background noise. Our work not only provides a compact, filter-free, and noise-robust detector for colorful image extraction in a metasurface, but also paves the way for color imaging application of perovskite-like bandgap tunable materials.