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In the last twenty years, nanofabrication progress has allowed for the emergence of a new photodetector family, generally called low-dimensional solids (LDSs), among which the most important are two-dimensional (2D) materials, perovskites, and nanowires/quantum dots. They operate in a wide wavelength range from ultraviolet to far-infrared. Current research indicates remarkable advances in increasing the performance of this new generation of photodetectors. The published performance at room temperature is even better than reported for typical photodetectors. Several articles demonstrate detectivity outperforming physical boundaries driven by background radiation and signal fluctuations. This study attempts to explain these peculiarities. In order to achieve this goal, we first clarify the fundamental differences in the photoelectric effects of the new generation of photodetectors compared to the standard designs dominating the commercial market. Photodetectors made of 2D transition metal dichalcogenides (TMDs), quantum dots, topological insulators, and perovskites are mainly considered. Their performance is compared with the fundamental limits estimated by the signal fluctuation limit (in the ultraviolet region) and the background radiation limit (in the infrared region). In the latter case, Law 19 dedicated to HgCdTe photodiodes is used as a standard reference benchmark. The causes for the performance overestimate of the different types of LDS detectors are also explained. Finally, an attempt is made to determine their place in the global market in the long term.

The paper presents the long-term evolution and recent development of ultraviolet photodetectors. First, the general theory of ultraviolet (UV) photodetectors is briefly described. Then the different types of detectors are presented, starting with the older photoemission detectors through photomultipliers and image intensifiers. More attention is paid to silicon and different types of wide band gap semiconductor photodetectors such as AlGaN, SiC-based, and diamond detectors. Additionally, Ga2O3 is considered a promising material for solar-blind photodetectors due to its excellent electrical properties and a large bandgap energy. The last part of the paper deals with new UV photodetector concepts inspired by new device architectures based on low-dimensional solid materials. It is shown that the evolution of the architecture has shifted device performance toward higher sensitivity, higher frequency response, lower noise, and higher gain-bandwidth products.

At the current stage of long-wavelength infrared (LWIR) detector technology development, the only commercially available detectors that operate at room temperature are thermal detectors. However, the efficiency of thermal detectors is modest: they exhibit a slow response time and are not very useful for multispectral detection. On the other hand, in order to reach better performance (higher detectivity, better response speed, and multispectral response), infrared (IR) photon detectors are used, requiring cryogenic cooling. This is a major obstacle to the wider use of IR technology. For this reason, significant efforts have been taken to increase the operating temperature, such as size, weight and power consumption (SWaP) reductions, resulting in lower IR system costs. Currently, efforts are aimed at developing photon-based infrared detectors, with performance being limited by background radiation noise. These requirements are formalized in the Law 19 standard for P-i-N HgCdTe photodiodes. In addition to typical semiconductor materials such as HgCdTe and type-II AIIIBV superlattices, new generations of materials (two-dimensional (2D) materials and colloidal quantum dots (CQDs)) distinguished by the physical properties required for infrared detection are being considered for future high-operating-temperature (HOT) IR devices. Based on the dark current density, responsivity and detectivity considerations, an attempt is made to determine the development of a next-gen IR photodetector in the near future.

The review includes results of analyses and research aimed at standardizing the concepts and measurement procedures associated with photodetector parameters. Photodetectors are key components that ensure the conversion of incoming optical radiation into an electrical signal in a wide variety of sophisticated optoelectronic systems and everyday devices, such as smartwatches and systems that measure the composition of the Martian atmosphere. Semiconductor detectors are presented, and they play a major role due to their excellent optical and electrical parameters as well as physical parameters, stability, and long mean time to failure. As their performance depends on the manufacturing technology and internal architecture, different types of photodetectors are described first. The following parts of the article concern metrological aspects related to their characterization. All the basic parameters have been defined, which are useful both for their users and their developers. This allows for the verification of photodetectors’ workmanship quality, the capabilities of a given technology, and, above all, suitability for a specific application and the performance of the final optoelectronic system. Experimentally validated meteorological models and equivalent diagrams, which are necessary for the correct analysis of parameter measurements, are also presented. The current state of knowledge presented in recognized scientific papers and the results of the authors’ works are described as well.

Graphene exhibits the longest carrier mean free path of any known electronic material, yet only a few device concepts have successfully leveraged this exceptional property. Here, we present a ballistic graphene rectifier capable of operating at frequencies up to 3 THz, significantly extending the limits of direct current (DC) generation through rectification in two‐dimensional materials. By engineering asymmetric nanojunction geometries in high‐mobility monolayer graphene encapsulated in hBN, we harness ballistic transport over >100 nm length scales to achieve efficient rectification without relying on p–n junctions or Schottky barriers. The devices exhibit robust rectified signals, with voltage responsivities of 100 V/W, 20 pW/Hz 1/2 noise‐equivalent powers at room temperature, and minimum detectable powers of 30 nW, outperforming conventional semiconductor‐based rectifiers in the same frequency range. Our results establish a new pathway for passive THz detection and signal processing, highlighting the potential of graphene nanodevices for next‐generation high‐frequency technologies.

The capability of detecting visible and near infrared light within a narrow wavelength range is in high demand for numerous emerging application areas, including wearable electronics, the Internet of Things, computer vision, artificial vision and biosensing. Organic and perovskite semiconductors possess a set of properties that make them particularly suitable for narrowband photodetection. This has led to rising interest in their use towards such functionality, and has driven remarkable progress in recent years. Through a comparative analysis across an extensive body of literature, this review provides an up-to-date assessment of this rapidly growing research area. The transversal approach adopted here focuses on the identification of: (a) the unifying aspects underlying organic and perovskite narrowband photodetection in the visible and in the near infrared range; and (b) the trends relevant to photoconversion efficiency and spectral width in relation to material, device and processing strategies. A cross-sectional view of organic and perovskite narrowband photodetection is thus delineated, giving fresh insight into the status and prospects of this research area.

Solar-blind ultraviolet photodetectors are gaining attention for their high signal-to-noise ratio and strong anti-interference capabilities. With the rising demand for applications in high-strain environments, such as fire rescue robots and smart firefighting suits, a flexible photodetector that maintains stable performance under bending strain is needed. Current devices struggle to balance strain cycle stability and responsivity. This paper presents a β-Ga[sub.2] O[sub.3] nanowire photodetector on a flexible ultra-thin silicon substrate, fabricated using microchannel engraving and chemical vapor deposition. The device achieves a responsivity of 266 mA W[sup.−1] without strain, with less than 5.5% variation in photogenerated current under bending strain (0–60°), and a response time of 360 ms. After 500 cycles of 60° bending, the photogenerated current changes by only 1.5%, demonstrating excellent stability and responsivity, with broad application potential in flame detection and biological sensing.

In the fast‐evolving landscape of decentralized and personalized healthcare, the need for multimodal biosensing systems that integrate seamlessly with the human body is growing rapidly. This presents a significant challenge in devising ultraflexible configurations that can accommodate multiple sensors and designing high‐performance sensing components that remain stable over long periods. To overcome these challenges, ultraflexible organic photodetectors (OPDs) that exhibit exceptional performance under near‐infrared illumination while maintaining long‐term stability are developed. These ultraflexible OPDs demonstrate a photoresponsivity of 0.53 A W−1 under 940 nm, shot‐noise‐limited specific detectivity of 3.4 × 1013 Jones, and cut‐off response frequency beyond 1 MHz at −3 dB. As a result, the flexible photoplethysmography sensor boasts a high signal‐to‐noise ratio and stable peak‐to‐peak amplitude under hypoxic and hypoperfusion conditions, outperforming commercial finger pulse oximeters. This ensures precise extraction of blood oxygen saturation in dynamic working conditions. Ultraflexible OPDs are further integrated with conductive polymer electrodes on an ultrathin hydrogel substrate, allowing for direct interface with soft and dynamic skin. This skin‐integrated sensing platform provides accurate measurement of photoelectric and biopotential signals in a time‐synchronized manner, reproducing the functionality of conventional technologies without their inherent limitations. Ultraflexible organic photodetectors (OPDs) exhibiting high performance at near‐infrared wavelengths are developed, based on which a skin‐integrated multimodal system enabling time‐synchronized monitoring of photoelectric and biopotential signals is constructed. The sub‐20 µm‐thick system comprises OPDs, conductive bioelectrodes, and a hydrogel substrate. The seamless integration between the sensing components and the skin enables precise tracking of multiple vital signs with long‐term stability.

Underwater imaging technology plays a pivotal role in marine exploration and reconnaissance, necessitating photodetectors (PDs) with high responsivity, fast response speed, and low preparation costs. This study presents the synergistic optimization of responsivity and response speed in self‐powered photoelectrochemical (PEC)‐type photodetector arrays based on oxygen‐vacancy‐tuned amorphous gallium oxide (a‐Ga2O3) thin films, specifically designed for solar‐blind underwater detection. Utilizing a low‐cost one‐step sputtering process with controlled oxygen flow, a‐Ga2O3 thin films with varying oxygen vacancy (VO) concentrations are fabricated. By balancing the trade‐offs among electrocatalytic reactions, charge transfer, carrier recombination, and trapping, both the responsivity and response speed of a‐Ga2O3‐based self‐powered PEC‐PDs are simultaneously improved. Consequently, the optimized PEC‐PDs demonstrated exceptional performance, achieving a responsivity of 33.75 mA W−1 and response times of 12.8 ms (rise) and 31.3 ms (decay), outperforming the vast majority of similar devices. Furthermore, a pronounced positive correlation between anomalous transient photocurrent spikes and the concentration of VO defects is observed, offering compelling evidence for VO‐mediated indirect recombination. Finally, the proof‐of‐concept solar‐blind underwater imaging system, utilizing an array of self‐powered PEC‐PDs, demonstrated clear imaging capabilities in seawater. This work provides valuable insight into the potential for developing cost‐effective, high‐performance a‐Ga2O3 thin‐film‐based PEC‐PDs for advanced underwater imaging technology. Simultaneously enhancing responsivity and response speed in oxygen‐vacancy‐tuned amorphous Ga2O3 thin‐film photoelectrochemical‐type self‐powered photodetectors involves balancing trade‐offs among electrocatalytic reactions, charge transfer, carrier recombination, and trapping. Transient photocurrent is closely associated with VO defects. The proof‐of‐concept underwater imaging system utilizes self‐powered photodetectors to demonstrate clear solar‐blind imaging in seawater, with potential future applications in marine exploration and reconnaissance.

With the rapid development of micro-nano technology and wearable devices, flexible photodetectors (PDs) have drawn widespread interest in areas such as healthcare, consumer electronics, and intelligence interfaces. Two-dimensional (2D) materials with layered structures have excellent optoelectronic properties and mechanical flexibility, which attract a great deal of attention in flexible applications. Although photodetectors based on mechanically exfoliated 2D materials have demonstrated superior performance compared to traditional Si-based PDs, large-scale manufacturing and flexible integration remain significant challenges for achieving industrial production. The emerging various printing technology provides a low-cost and highly effective method for integrated manufacturing. In this review, we comprehensively introduce the most recent progress on printed flexible 2D material PDs. We first reviewed the most recent research on flexible photodetectors, in which the discussion is focused on substrate materials, functional materials, and performance figures of merits. Furthermore, the solution processing for 2D materials coupled with printing functional film strategies to produce PDs are summarized. Subsequently, the various applications of flexible PDs, such as image sensors, healthcare, and wearable electronics, are also summarized. Finally, we point out the potential challenges of the printed flexible 2D material PDs and expect this work to inspire the development of flexible PDs and promote the mass manufacturing process.