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Due to the inherent high dark current of photoelectrochemical (PEC)‐type photodetectors (PDs), there is a tricky challenge to detect weak light. In this work, high‐quality Cd0.9Pb0.1Se quantum dots (CPS QDs) are prepared by thermal injection method, with horizontal size of 6.3 nm and thickness of 3.5 nm. The CPS QDs are directly utilized to construct the working electrode of PEC‐type PDs. The effects of experimental parameters on the photo‐response behavior are systematically studied, and optimized photocurrent density of 7.1 µA cm−2 and photo‐responsivity (Rph) of 2.75 mA·W−1 are achieved. Most importantly, the obvious photocurrent signals are observed under a light power density as low as 5.6 µW cm−2. For this interesting weak light detection, apparent Rph of 6.96 mA·W−1, detectivity of 1.2 × 109 Jones, and external quantum efficiency of 2.37% are achieved. Therefore, this work not only develops CPS QDs‐based PDs but also provides an example for PEC‐type PDs in weak light detection. [ABSTRACT FROM AUTHOR]

In this letter, an enhanced coprime array with compressed inter‐element spacing is designed for direction of arrival estimation. First, we analyse and conclude that the 0th sensor of coprime array with compressed inter‐element spacing is redundant for the consecutive lags, thus it is rearranged to the negative part to obtain enhanced coprime array with compressed inter‐element spacing. Then, on the basis of discussing the effect of the shift sensor on the difference co‐array, the number of unique lags and the range of consecutive lags are derived. Theoretical properties show that the closed‐form expressions of coprime array with compressed inter‐element spacing and enhanced coprime array with compressed inter‐element spacing are similar, while more difference lags can be generated from the latter. Moreover, larger inter‐element spacing can slightly alleviate the mutual coupling. Numerical examples verify the advantages of enhanced coprime array with compressed inter‐element spacing in direction of arrival estimation over coprime array with compressed inter‐element spacing configuration and other coprime arrays. [ABSTRACT FROM AUTHOR]

In recent decades, quantum dots (QDs) with tunable bandgap, large absorption coefficient, high quantum yield, multiexciton effect, and easy solution processing have unparalleled advantages in photoelectric conversion. Optoelectronic devices based on QDs of different composition have made great progress. However, there is still a lack of reviews on comparing the optoelectronic application level of semiconductor quantum dots (SQDs), perovskite quantum dots (PQDs), and carbon quantum dots (CDs), and also rarely providing a comprehensive summary of photocatalysis. First, this review almost completely summarizes advantages and disadvantages of common synthesis methods for QDs, especially pointing out the importance of optimization strategies for preparing high‐quality QDs such as ligand engineering, ion exchange, and purification separation. Then, compositions of SQD, PQD, CD, and corresponding optoelectronic properties are introduced, respectively. Next, the strengths and weaknesses of the four QDs structures are compared in detail. Finally, the flourishing development in various optoelectronic applications is separately demonstrated, and development degree of SQDs, PQDs, and CDs is compared to discover the most suitable application scenarios for each. On these bases, bottlenecks and opportunities are also put forwarded, hoping to stimulate more breakthroughs in this field. [ABSTRACT FROM AUTHOR]

High‐entropy (HE) MXenes represent a novel class of 2D materials within the MXene family, which are drawing widespread attention because of their diverse compositions and robust physicochemical properties. However, the exploration of HE‐MXenes in optoelectronic domains is relatively limited. This study unveils the rapid photoresponse and superior nonlinear optical (NLO) characteristics of HE‐MXene TiVCrMoC3Tx nanosheets (NSs) through comparison with ordinary MXene Ti3C2Tx NSs. Transient absorption spectroscopy reveals that the few‐layer TiVCrMoC3Tx NSs excel in photoelectrochemical‐type photodetectors with swift response properties. Additionally, the advantage of HE structures is further validated by NLO measurement system, which show that few‐layer TiVCrMoC3Tx NSs exhibit stronger saturable absorption than Ti3C2Tx NSs. First‐principles calculations based on the special quasi‐random structure method reveal that the transition behavior of HE‐MXene is similar to that of a semiconductor with direct bandgap, and this is ascribed to the main reason of strong photoelectric response. Taking advantage of the NLO properties of the TiVCrMoC3Tx NSs, all‐optical devices based on these NSs are applied to mode‐locked fiber lasers at 1, 1.5, and 2 µm wavebands, respectively. This investigation provides meaningful guidance for the future design and application of HE‐MXenes in high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

2D atomically thin graphdiyne oxide (GDYO) nanosheets (NSs) are synthesized, and their nonlinear modulation is investigated. Generally, improving the modulation depth (MD) of all‐optical modulation (AOM) requires a pump light with strong power, which limits the development of AOM technology in the design of low‐power loss devices. In this study, an AOM system based on spatial self‐phase modulation and spatial cross‐phase modulation methods is proposed using 2D GDYO NSs. The results reveal that 2D GDYO exhibits tunable nonlinearity and high stability, which is desirable for designing the AOM system. Because of the excellent optical properties of 2D GDYO, a large MD of >98% is achieved for the proposed AOM with a low power of pump light, which is higher than most AOMs currently reported. Thus, GDYO is an excellent modulation material in AOM, which improves the application prospects of carbon nanomaterials in all‐optical devices. [ABSTRACT FROM AUTHOR]

To address the problems of traditional two‐level nested arrays (TTNA) with low degrees of freedom and high mutual coupling, a generalised two‐level nested MIMO radar array with high degrees of freedom and low mutual coupling for the direction of arrival (DOA) estimation is proposed. First, two coprime expansion factors are introduced in the TTNA to mitigate mutual coupling among array elements and enhance its degrees of freedom. Secondly, the range of consecutive lags and the total number of virtual array elements are derived in closed form under the structures of 'sum–difference co‐array'. Finally, utilising the atomic norm minimisation theory, the authors address the issue of discrete holes caused by different coprime expansion factors through filling in virtual arrays at discontinuities. Furthermore, a convex optimisation model to recover equivalent received signals from these filled virtual arrays is established, which is combined with a multiple signal classification algorithm for DOA estimation. Simulation results validate the rationality of the array structure and demonstrate the effectiveness of the algorithm. [ABSTRACT FROM AUTHOR]

Immunotherapy, especially immune checkpoint blockade (ICB) antibody immunotherapy, has revolutionized the treatment ways of cancers and provided remarkable clinical benefits for multiple cancers. However, the efficacy of immunotherapy in tumors with an immune‐excluded or immune‐suppressed phenotype is dismal due to the lack or paucity of immune infiltration in the tumor microenvironment. Herein, an emerging photoimmunotherapy based on remodeling the inflammatory microenvironment is reported, ascribed to nanoagonist‐mediated gasdermin E (GSDME)‐dependent pyroptosis and providing positive feedback to activate anti‐PD‐1 immunotherapy. An iridium‐based photosensitizer (IrP) carrying methyltransferase inhibitor RG108 (R@IrP) lead to rapid cell pyroptosis via the caspase‐3/GSDME pathway under the light activation. Furthermore, light‐elicited pyroptosis synergized with anti‐PD‐1 to induce anti‐tumor photoimmunotherapy. The pro‐inflammatory factors released by pyroptotic cells remodel the inflammatory microenvironment and recruit immune cells to kill tumor cells, resulting in CD8+ cytotoxic T lymphocytes activation, PD‐1 expression enhancement, and dendritic cell slightly maturation. Collectively, these findings present a synergistic strategy of photoimmunotherapy, that is, turning immunological cold tumors into hot tumors that can respond to anti‐PD‐1‐based immunotherapy via precise pathway regulation. [ABSTRACT FROM AUTHOR]