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Photoresponsive drug delivery systems (PDDSs) have emerged as a promising toolbox for drug delivery, offering precise control over the site, duration, and dosage of light‐triggered medication. It allows controlled drug release, photo‐triggered targeting, diagnosis, and treatment, improving the precision and efficacy of therapies for various diseases. Despite progress in designing different PDDSs, clinical translation has been limited due to various obstacles. Herein, this review article focuses on three critical challenges of PDDSs: 1) accumulation at diseased lesions, 2) precision of light irradiation, and 3) penetration of light in tissues. Also, this article summarizes and discusses current advancements and strategies to address these challenges. Overall, it emphasizes the need to clarify the current challenges from bench to bedside and develop strategies to enhance therapeutic outcomes, increase compatibility and patient compliance, and unlock the possibilities in different clinical therapies. [ABSTRACT FROM AUTHOR]

Bi‐directional photodetection with positive and negative photoconductance (PPC/NPC) plays a critical role in building next‐generation artificial neuromorphic systems, visual information processing and optoelectronic logic gates of the future. However, the typical device configuration based on heterostructures with strict working principles restricts the diversity of material selection. In this work, a novel strategy is proposed to fabricate bi‐directional photoresponse devices based on PtSe2−x films with precisely controllable selenization engineering. It is found that the PtSe2−x films are composed of Pt and PtSe2 components. The direction of the photocurrent can be reversibly modulated in a broadband range by tuning the ratio of PtSe2 in the film, which is ascribed to the synergistic mechanism of bolometric effect of Pt and photoconductive effect of PtSe2. The polarity switching wavelength from NPC to PPC can be further modulated through tuning the components of the film for specific demand. The tunable bi‐directional photoresponse enables the device to mimic the fundamental functions of artificial synapses all optically, such as aversion learning capability and logical functions, with high paired pulse facilitation index. This work potentially opens an opportunity for the development of advanced artificial neuromorphic systems and optoelectronic logic gates. [ABSTRACT FROM AUTHOR]

2D materials and their van der Waals heterostructures are of great fundamental interest and have potential applications in emerging electronics devices. However, atomically thin photodetector applications have suffered from performance limitations because of low optical absorption. Here, a near‐infrared photodetector based on methylammonium lead halide perovskite quantum dots (MQDs), combined with Ta2NiSe5 van der Waals heterostructures, is fabricated to take advantage of their energy band alignment. An ultrasensitive photoresponse with a detectivity of 6.0 × 1012 Jones for 800 nm illumination is demonstrated. Furthermore, the field‐effect mobility and responsivity are enhanced by factors of 2 and 7.4, respectively, by interfacing Ta2NiSe5 and the MQDs. These results indicate that the optoelectrical properties of 2D ternary Ta2NiSe5 can be significantly optimized via hybridization with MQDs and can accelerate the evolution of MQD‐van der Waals heterostructure‐based devices. [ABSTRACT FROM AUTHOR]

Theoretical and experimental investigations of various exfoliated samples taken from layered In4Se3 crystals are performed. In spite of the ionic character of interlayer interactions in In4Se3 and hence much higher calculated cleavage energies compared to graphite, it is possible to produce few‐nanometer‐thick flakes of In4Se3 by mechanical exfoliation of its bulk crystals. The In4Se3 flakes exfoliated on Si/SiO2 have anisotropic electronic properties and exhibit field‐effect electron mobilities of about 50 cm2 V−1 s−1 at room temperature, which are comparable with other popular transition metal chalcogenide (TMC) electronic materials, such as MoS2 and TiS3. In4Se3 devices exhibit a visible range photoresponse on a timescale of less than 30 ms. The photoresponse depends on the polarization of the excitation light consistent with symmetry‐dependent band structure calculations for the most expected ac cleavage plane. These results demonstrate that mechanical exfoliation of layered ionic In4Se3 crystals is possible, while the fast anisotropic photoresponse makes In4Se3 a competitive electronic material, in the TMC family, for emerging optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Information processing with optoelectronic devices provides an alternative way to efficiently process hybrid optical and electronic signals. Ferroelectric field‐effect transistors (FeFETs) can effectively respond to external optical and electrical stimuli by modulating their polarization states. Here, a 2D FeFET is demonstrated by the epitaxial growth of high‐quality 2D bismuth layered oxyselenide (Bi2O2Se) films on PMN‐PT(001) ferroelectric single‐crystal substrates. Upon switching the polarization direction of PMN‐PT, the authors realize in situ, reversible, and nonvolatile manipulation of the resistance of Bi2O2Se thin film (≈877%). The device simultaneously exhibits a polarization‐dependent photoresponse through visible light (λ = 405 nm) and infrared light (IR, λ = 980 nm) illumination. Combining optical stimuli with ferroelectric gating, it is demonstrated that the devices not only show nonvolatile memory and optoelectronic responses, but also show coincidence detection of visible and IR light. This work holds great potential in constructing new multiresponse and multifunction 2D‐FeFETs. [ABSTRACT FROM AUTHOR]

β-In2S3 is a natural defective III--VI semiconductor attracting considerable interests but lack of efficient method for its 2D form fabrication. Here, for the first time, this paper reports controlled synthesis of ultrathin 2D β-In2S3 flakes via a facile space-confined chemical vapor deposition method. The natural defects in β-In2S3 crystals, clearly revealed by optical spectra and optoelectronic measurement, strongly modulate the (opto)-electronic of as-fabricated β-In2S3 and render it a broad detection range from visible to near-infrared. Particularly, the as-fabricated β-In2S3 photodetector shows a high photoresponsivity of 137 A W-1, a high external quantum efficiency of 3.78 x 104%, and a detectivity of 4.74 x 1010 Jones, accompanied with a fast rise and decay time of 6 and 8 ms, respectively. In addition, an interesting linear response to the testing power intensities range is observed, which can also be understood by the presence of natural defects. The unique defective structure and intrinsic optical properties of β-In2S3, together with its controllable growth, endow it with great potential for future applications in electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

Due to the novel optical and optoelectronic properties, 2D materials have received increasing interests for optoelectronics applications. Discovering new properties and functionalities of 2D materials is challenging yet promising. Here broadband polarization sensitive photodetectors based on few layer ReS2 are demonstrated. The transistor based on few layer ReS2 shows an n-type behavior with the mobility of about 40 cm2 V−1 s−1 and on/off ratio of 105. The polarization dependence of photoresponse is ascribed to the unique anisotropic in-plane crystal structure, consistent with the optical absorption anisotropy. The linear dichroic photodetection with a high photoresponsivity reported here demonstrates a route to exploit the intrinsic anisotropy of 2D materials and the possibility to open up new ways for the applications of 2D materials for light polarization detection. [ABSTRACT FROM AUTHOR]

Due to the novel optical and optoelectronic properties, 2D materials have received increasing interests for optoelectronics applications. Discovering new properties and functionalities of 2D materials is challenging yet promising. Here broadband polarization sensitive photodetectors based on few layer ReS2 are demonstrated. The transistor based on few layer ReS2 shows an n-type behavior with the mobility of about 40 cm2 V−1 s−1 and on/off ratio of 105. The polarization dependence of photoresponse is ascribed to the unique anisotropic in-plane crystal structure, consistent with the optical absorption anisotropy. The linear dichroic photodetection with a high photoresponsivity reported here demonstrates a route to exploit the intrinsic anisotropy of 2D materials and the possibility to open up new ways for the applications of 2D materials for light polarization detection. [ABSTRACT FROM AUTHOR]

Organic-inorganic heterostructures are an emerging topic that is very interesting for optoelectronics. Here, non-conventional p-n junctions are investigated using organic rubrene single crystal and 2D MoS2 as the p- and n-type semiconducting materials, respectively. The current-rectifying behavior is clearly observed in the junction device. The rectification ratio can be electrically tuned by the gate voltage due to the 2D nature of the heterostructure. The devices also show good photoresponse properties with a photoresponsivity of ≈500 mA W−1 and a fast response time. These findings suggest a new route to facilitate the design of nanoelectronic and optoelectronic devices based on layered inorganics and organics. [ABSTRACT FROM AUTHOR]

Atomically thin 2D layered transition metal dichalcogenides (TMDs) have been extensively studied in recent years because of their appealing electrical and optical properties. Here, the fabrication of ReS2 field-effect transistors is reported via the encapsulation of ReS2 nanosheets in a high- κ Al2O3 dielectric environment. Low-temperature transport measurements allow to observe a direct metal-to-insulator transition originating from strong electron-electron interactions. Remarkably, the photodetectors based on ReS2 exhibit gate-tunable photoresponsivity up to 16.14 A W−1 and external quantum efficiency reaching 3168%, showing a competitive device performance to those reported in graphene, MoSe2, GaS, and GaSe-based photodetectors. This study unambiguously distinguishes ReS2 as a new candidate for future applications in electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

The preparation of patterned photoswitchable surfaces by employing the nitrile imine-mediated tetrazole ene cycloaddition (NITEC) photoinduced reaction in the presence of dipolarophiles based on photoresponsive azobenzene moieties is reported. The dipolarophile used is a maleimide carrying either an azobenzene unit or a first generation dendron containing two azobenzene units. X-ray photoelectron spectroscopy (XPS) is employed to analyze the functionalized silicon wafers, while time-of-flight secondary ion mass spectrometry (ToF-SIMS) evidences the spatial control of the functionalization of the surface achieved by using a micropatterned shadow mask. Water contact angle measurements and optical inspection observing the behavior of a water droplet demonstrate the photoinduced change on wettability of the structured functionalized surfaces due to the reversible trans-to- cis isomerization of the azobenzene moities. [ABSTRACT FROM AUTHOR]

Enhanced carrier-carrier interactions in hybrid nanostructures exhibit exceptional electronic and optoelectronic properties. Carbon nanotubes demonstrate excellent switching behavior with high on/off ratio and high mobility but do not show photoresponse in the visible range, whereas quantum dots (QDs) shows excellent optical response in various optical ranges which can be tuned with diameter. Here, a simple and effective way to develop hybrid phototransistors with extraordinary optoelectronic properties is presented by decorating semiconducting QDs on the surface of a single-walled carbon nanotube (SWCNT). This hybrid structure demonstrates clear negative photoresponse and optical switching behavior, which could be further tuned by applying external gate bias in the future. A clear type conversion of SWCNT transistor from p-type to n-type caused by a charge transfer from attached QDs to CNT is demonstrated. Moreover, this hybrid structure also demonstrates an enhancement in 'optical Stark effect' without applying any external electric field. Charged SWCNT surface plays a key role behind the enhancement of optical Stark effect in QDs. The carrier dynamics of the QD and CNT heterostructures system highlights the potential application opportunity of the quantum dot systems, which can be adaptable to the current technologies. [ABSTRACT FROM AUTHOR]

Light polarization is an important concept in optics for generation, detection and manipulation of light. ReS2, a highly anisotropic two‐dimensional material, has excellent capabilities for high detection sensitivity of polarized light, as shown by X. He, Z. Liu, and co‐workers on page 1169. Atomically thin ReS2 may pave a promising way to applications in integrated photonic circuits, optical switches and interconnects for detecting the various orientations of linearly polarized light in a highly integrated photonic platform. [ABSTRACT FROM AUTHOR]

A simple and effective way to develop hybrid phototransistors with extraordinary optoelectronic properties is demonstrated by M. S. Jeong, Y. H. Lee and co‐workers. On page 3653, they decorate singlewalled carbon nanotube (SWCNT) surfaces with semiconducting quantum dots. This hybrid structure shows a clear negative photoresponse and optical switching behavior, which could be further tuned by applying an external gate bias. Moreover, this hybrid structure shows an enhancement in the ‘optical Stark effect’ without applying any external electric field. [ABSTRACT FROM AUTHOR]