High detectivity solar blind photodetector based on mechanical exfoliated hexagonal boron nitride films

As an ultra-wide bandgap semiconductor, hexagonal boron nitride (h-BN) has drawn great attention in solar-blind photodetection owing to its wide bandgap and high thermal conductivity. In this work, a metal-semiconductor-metal structural two-dimensional h-BN photodetector was fabricated by using mechanically exfoliated h-BN flakes. The device achieved an ultra-low dark current (16.4 fA), high rejection ratio (R_205nm/R_280nm= 235) and high detectivity up to 1.28 × 10¹¹Jones at room temperature. Moreover, due to the wide bandgap and high thermal conductivity, the h-BN photodetector showed good thermal stability up to 300 °C, which is hard to realize for common semiconductor materials. The high detectivity and thermal stability of h-BN photodetector in this work showed the potential applications of h-BN photodetectors working in solar-blind region at high temperature.

Fabrication of High-Performance Visible-Blind Ultraviolet Photodetectors Using Electro-ionic Conducting Supramolecular Nanofibers

The detection of ultraviolet (UV) light is vital for various applications, such as chemical-biological analysis, communications, astronomical studies, and also for its adverse effects on human health. Organic UV photodetectors are gaining much attention in this scenario because they possess properties such as high spectral selectivity and mechanical flexibility. However, the achieved performance parameters are much more inferior than the inorganic counterparts because of the lower mobility of charge carriers in organic systems. Here, we report the fabrication of a high-performance visible-blind UV photodetector, using 1D supramolecular nanofibers. The nanofibers are visibly inactive and exhibit highly responsive behavior mainly for UV wavelengths (275-375 nm), the highest response being at ∼275 nm. The fabricated photodetectors demonstrate desired features, such as high responsivity and detectivity, high selectivity, low power consumption, and good mechanical flexibility, because of their unique electro-ionic behavior and 1D structure. The device performance is shown to be improved by several orders through the tweaking of both electronic and ionic conduction pathways while optimizing the electrode material, external humidity, applied voltage bias, and by introducing additional ions. We have achieved optimum responsivity and detectivity values of around 6265 A W^-1 and 1.54 × 10¹⁴ Jones, respectively, which stand out compared with the previous organic UV photodetector reports. The present nanofiber system has great potential for integration in future generations of electronic gadgets.

Multiwavelength High-Detectivity MoS2 Photodetectors with Schottky Contacts

Photodetection is one of the vital functions for the multifunctional "More than Moore" (MtM) microchips urgently required by Internet of Things (IoT) and artificial intelligence (AI) applications. The further improvement of the performance of photodetectors faces various challenges, including materials, fabrication processes, and device structures. We demonstrate in this work MoS₂ photodetectors with a nanoscale channel length and a back-gate device structure. With the mechanically exfoliated six-monolayer-thick MoS₂, a Schottky contact between source/drain electrodes and MoS₂, a high responsivity of 4.1 × 10³ A W^-1, and a detectivity of 1.34 × 10¹³ cm Hz^1/2 W^-1 at 650 nm were achieved. The devices are also sensitive to multiwavelength lights, including 520 and 405 nm. The electrical and optoelectronic properties of the MoS₂ photodetectors were studied in depth, and the working mechanism of the devices was analyzed. The photoinduced Schottky barrier lowering (PIBL) was found to be important for the high performance of the phototransistor.

Doping Compensation Enables High-Detectivity Infrared Organic Photodiodes for Image Sensing

Infrared organic photodiodes have gained increasing attention due to their great application potentials in night vision, optical communication, and all-weather imaging. However, the commonly occurring high dark current and low detectivity impede infrared photodetectors from portable applications at room temperature. Herein, an efficient and generic doping compensation strategy is developed to improve the detectivity of infrared organic photodiodes. A series of n-type organic semiconductors is investigated, and it is found that doping compensation strategy not only reduces the trap density of states and dark currents, but also restrains the nonradiative recombination with improved charge transport and collection. As a result, an ultralow noise spectral density of 8 × 10^-15 A Hz^-1/2 as well as a high specific detectivity over 10¹³ Jones in 780-1070 nm is achieved at room temperature. More importantly, the high-performance infrared organic photodiodes can be successfully applied in high-pixel-density image arrays without patterning sensing layers. These findings provide important compensation design insights that will be crucial to further improve the performance of infrared organic photodiodes in the future.

Thermally Stable Organic Field-Effect Transistors Based on Asymmetric BTBT Derivatives for High Performance Solar-Blind Photodetectors

High-performance solar-blind photodetectors are widely studied due to their unique significance in military and industrial applications. Yet the rational molecular design for materials to possess strong absorption in solar-blind region is rarely addressed. Here, an organic solar-blind photodetector is reported by designing a novel asymmetric molecule integrated strong solar-blind absorption with high charge transport property. Such alkyl substituted [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) derivatives Cn-BTBTN (n = 6, 8, and 10) can be easily assembled into 2D molecular crystals and perform high mobility up to 3.28 cm² V^-1 s^-1 , which is two orders of magnitude higher than the non-substituted core BTBTN. Cn-BTBTNs also exhibit dramatically higher thermal stability than the symmetric alkyl substituted C8-BTBT. Moreover, C10-BTBTN films with the highest mobility and strongest solar-blind absorption among the Cn-BTBTNs are applied for solar-blind photodetectors, which reveal record-high photosensitivity and detectivity up to 1.60 × 10⁷ and 7.70 × 10¹⁴ Jones. Photodetector arrays and flexible devices are also successfully fabricated. The design strategy can provide guidelines for developing materials featuring high thermal stability and stimulating such materials in solar-blind photodetector application.

Photomultiplication-Type Organic Photodetectors for Near-Infrared Sensing with High and Bias-Independent Specific Detectivity

Highly responsive organic photodetectors allow a plethora of applications in fields like imaging, health, security monitoring, etc. Photomultiplication-type organic photodetectors (PM-OPDs) are a desirable option due to their internal amplification mechanism. However, for such devices, significant gain and low dark currents are often mutually excluded since large operation voltages often induce high shot noise. Here, a fully vacuum-processed PM-OPD is demonstrated using trap-assisted electron injection in BDP-OMe:C₆₀ material system. By applying only -1 V, compared with the self-powered working condition, the responsivity is increased by one order of magnitude, resulting in an outstanding specific detectivity of ≈10¹³  Jones. Remarkably, the superior detectivity in the near-infrared region is stable and almost voltage-independent up to -10 V. Compared with two photovoltaic-type photodetectors, these PM-OPDs exhibit the great potential to be easily integrated with state-of-the-art readout electronics in terms of their high responsivity, fast response speed, and bias-independent specific detectivity. The employed vacuum fabrication process and the easy-to-adapt PM-OPD concept enable seamless upscaling of production, paving the way to a commercially relevant photodetector technology.

Ultra-High Performance Amorphous Ga2 O3 Photodetector Arrays for Solar-Blind Imaging

The growing demand for scalable solar-blind image sensors with remarkable photosensitive properties has stimulated the research on more advanced solar-blind photodetector (SBPD) arrays. In this work, the authors demonstrate ultrahigh-performance metal-semiconductor-metal (MSM) SBPDs based on amorphous (a-) Ga2 O3 via a post-annealing process. The post-annealed MSM a-Ga2 O3 SBPDs exhibit superhigh sensitivity of 733 A/W and high response speed of 18 ms, giving a high gain-bandwidth product over 104 at 5 V. The SBPDs also show ultrahigh photo-to-dark current ratio of 3.9 × 107 . Additionally, the PDs demonstrate super-high specific detectivity of 3.9 × 1016 Jones owing to the extremely low noise down to 3.5 fW Hz-1/2 , suggesting high signal-to-noise ratio. Underlying mechanism for such superior photoelectric properties is revealed by Kelvin probe force microscopy and first principles calculation. Furthermore, for the first time, a large-scale, high-uniformity 32 × 32 image sensor array based on the post-annealed a-Ga2 O3 SBPDs is fabricated. Clear image of target object with high contrast can be obtained thanks to the high sensitivity and uniformity of the array. These results demonstrate the feasibility and practicality of the Ga2 O3 PDs for applications in solar-blind imaging, environmental monitoring, artificial intelligence and machine vision.

Enhanced Static and Dynamic Properties of Highly Miscible Fullerene-Free Green-Selective Organic Photodetectors

We developed p-n junction organic photodetectors (OPDs) composed of a polymer donor and a nonfullerene acceptor (NFA) to increase both the responsivity (R) and detectivity (D*) while maintaining a narrow wavelength selectivity. The selection of the polymer donor and NFA with similar green (G) absorption is important for achieving G-wavelength selectivity in these OPDs, which differentiates them from current fullerene-based OPDs and NFA-based panchromatic absorption OPDs. In addition, mixing the polymer donor and asymmetric NFA was efficient toward increasing the miscibility and decreasing the interfacial energy difference of the blended films, resulting in the formation of a uniform and well-mixed nanomorphology in the photoconductive layer. Two-dimensional (2D) grazing incidence X-ray diffraction and Fourier-transform infrared spectroscopy revealed that the lamellar ordering of the polymer donor was enhanced in the blend film prepared with an asymmetric NFA, whereas the aggregation of a symmetric NFA in the blend films did not increase the lamellar ordering of the polymer donor. Consequently, we achieved an R value of 0.31 A/W and D* value of 2.0 × 10¹³ Jones with a full width at half-maximum value of 230 nm at -2 V and fast response time of 27 μs without any external bias in the asymmetric NFA-based OPDs. The enhancement in the lamellar ordering and miscibility of the blended films are crucial toward increasing the static and dynamic properties of OPDs.

Steep-Slope Gate-Connected Atomic Threshold Switching Field-Effect Transistor with MoS2 Channel and Its Application to Infrared Detectable Phototransistors

For next-generation electronics and optoelectronics, 2D-layered nanomaterial-based field effect transistors (FETs) have garnered attention as promising candidates owing to their remarkable properties. However, their subthreshold swings (SS) cannot be lower than 60 mV/decade owing to the limitation of the thermionic carrier injection mechanism, and it remains a major challenge in 2D-layered nanomaterial-based transistors. Here, a gate-connected MoS2 atomic threshold switching FET using a nitrogen-doped HfO2-based threshold switching (TS) device is developed. The proposed device achieves an extremely low SS of 11 mV/decade and a high on-off ratio of ≈106 by maintaining a high on-state drive current due to the steep switching of the TS device at the gate region. In particular, the proposed device can function as an infrared detectable phototransistor with excellent optical properties. The proposed device is expected to pave the way for the development of future 2D channel-based electrical and optical transistors.

Tunable Linearity of High-Performance Vertical Dual-Gate vdW Phototransistors

Layered 2D semiconductors have been widely exploited in photodetectors due to their excellent electronic and optoelectronic properties. To improve their performance, photogating, photoconductive, photovoltaic, photothermoelectric, and other effects have been used in phototransistors and photodiodes made with 2D semiconductors or hybrid structures. However, it is difficult to achieve the desired high responsivity and linear photoresponse simultaneously in a monopolar conduction channel or a p-n junction. Here, dual-channel conduction with ambipolar multilayer WSe₂ is presented by employing the device concept of dual-gate phototransistor, where p-type and n-type channels are produced in the same semiconductor using opposite dual-gating. It is possible to tune the photoconductive gain using a vertical electric field, so that the gain is constant with respect to the light intensity-a linear photoresponse, with a high responsivity of ≈2.5 × 10⁴ A W^-1 . Additionally, the 1/f noise of the device is kept at a low level under the opposite dual-gating due to the reduction of current and carrier fluctuation, resulting in a high detectivity of ≈2 × 10¹³ Jones in the linear photoresponse regime. The linear photoresponse and high performance of the dual-gate WSe₂ phototransistor offer the possibility of achieving high-resolution and quantitative light detection with layered 2D semiconductors.

Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High Detectivity

Continuously enhanced photoresponsivity and suppressed dark/noise current combinatorially lead to the recent development of high-detectivity organic photodetectors with broadband sensing competence. Despite the achievements, reliable photosensing enabled by organic photodetectors (OPDs) still faces challenges. Herein, we call for heed over a universal phenomenon of detrimental sensitivity of dark current to illumination history in high-performance inverted OPDs. The phenomenon, unfavorable to the attainment of high sensitivity and consistent figures-of-merit, is shown to arise from exposure of the commonly used electron transport layer in OPDs to high-energy photons and its consequent loss of charge selectivity via systematic studies. To solve this universal problem, "double" layer tin oxide as an alternative electron transport layer is demonstrated, which not only eliminates the inconsistency between the initial and after-illumination dark current characteristics but also preserves the low magnitude of dark current, good external quantum efficiency, and rapid transient response.

Copper Thiocyanate as an Anode Interfacial Layer for Efficient Near-Infrared Organic Photodetector

Interfacial modification between the electrode and the overlying organic layer has significant effects on the charge injection and collection and thus the device performance of organic photodetectors. Here, we used copper(I) thiocyanate (CuSCN) as the anode interfacial layer for organic photodetector, which was inserted between the anode and an organic light-sensitive layer. The CuSCN layer processed with ethyl sulfide solution presented similar optical properties to the extensively used anode interlayer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), while the relatively shallow conduction band of CuSCN resulted in a much higher electron-injection barrier from the anode and shunt resistance than those of PEDOT:PSS. Moreover, the CuSCN-based device also exhibited an increased depletion width for the PEDOT:PSS-based device, as indicated by the Mott-Schottky analysis. These features lead to the dramatically reduced dark current density of 2.7 × 10^-10 A cm^-2 and an impressively high specific detectivity of 4.4 × 10¹³ cm Hz^1/2 W^-1 under -0.1 V bias and a working wavelength of 870 nm. These findings demonstrated the great potential of using CuSCN as an anode interfacial layer for developing high-performance near-infrared organic photodetectors.

Additive Modulated Perovskite Microstructures for High Performance Photodetectors

Organic-inorganic hybrid perovskites have been widely used as light sensitive components for high-efficient photodetectors due to their superior optoelectronic properties. However, the unwanted crystallographic defects of perovskites typically result in high dark current, and thus limit the performance of the device. Herein, we introduce a simple route of microstructures control in MAPbI₃ perovskites that associates with introducing an additive of 3,3,4,4-benzophenonetetracarboxylic dianhydridean (BPTCD) for crystallization adjustment of the perovskite film. The BPTCD additive can facilitate the formation of high-quality perovskite film with a compact and nearly pinhole-free morphology. Through characterizing the molecular interactions, it was found that the carbonyl groups in BPTCD is the key reason that promoted the nucleation and crystallization of MAPbI₃. As a result, we obtained high-efficient and stable perovskite photodetectors with low dark current of 9.98 × 10^-8 A at -0.5 V, an on/off ratio value of 10³, and a high detectivity exceeding 10¹² Jones over the visible region.

Significantly Enhanced Detectivity of CIGS Broadband High-Speed Photodetectors by Grain Size Control and ALD-Al2O3 Interfacial-Layer Modification

The Cu(In,Ga)Se₂ (CIGS) thin film has been commercialized as solar cells with great success, but its application for photodetectors still faces some practical challenges, including low detectivity and long response time. In this paper, the structure of the Mo/CIGS/CdS/ZnO/ITO heterojunction has been fabricated, and satisfactory performances of high detectivity and fast response time have been achieved by suppressing the dark current and enhancing the carrier mobility. The controllable growth of CIGS grains is accomplished through optimizing the selenization process, demonstrating that bigger grain sizes resulted in higher carrier mobility and better response characteristics. Particularly, the high rise/decay speed of 3.40/6.46 μs is achieved. Furthermore, the interface of the CIGS/CdS heterojunction has been modified by the Al₂O₃ layer via the atomic-layer deposition (ALD) process. The dark current of the device is effectively suppressed by the ALD-Al₂O₃ layer, which remarkably drops from ∼10^-7 to ∼10^-9 A. As a consequence, the detectivity rises from 3.08 × 10¹¹ to 1.84 × 10¹² Jones. In addition, the ALD-Al₂O₃ layer shows a protective effect as well, which is positive for photoelectrical conversion. Besides, the wide linear dynamic range of 102.1 dB and large -3 dB bandwidth of 78 kHz are acquired. This work suggests that the CIGS-based heterojunction has great potential for high-performance thin-film photodetectors.

High-Performance All-Polymer Photodetectors via a Thick Photoactive Layer Strategy

To achieve high detectivity in all-polymer photodetectors (all-PPDs), a thick-film photoactive layer is favored because it can effectively suppress the dark current density. However, if the photoactive layer of the film is too thick, it leads to reduced responsivity owing to increased recombination loss. We developed high-performance all-PPDs by using a narrowband-gap p-type polymer NT40 and an n-type polymer poly{[ N, N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt-5,5'-(2,2'bithiophene)} as the photoactive layer. The high charge carrier mobility of both copolymers enabled a photoactive layer thickness of 300 nm, leading to an ultralow dark current density of 4.85 × 10^-10 A cm^-2, a detectivity of 2.61 × 10¹³ Jones, a high responsivity of 0.33 A W^-1 at 720 nm, and a bias of -0.1 V. The detectivity achieved >10¹³ Jones in a wide range from 360 to 850 nm, which is among the highest values so far reported for all-PPDs without extra gains. More importantly, the resultant all-PPDs exhibited a high working frequency over 10 kHz associated with a large linear dynamic range. These findings demonstrate great potential for practical applications of the all-PPDs developed in this work.

Bifunctional Etalon-Electrode To Realize High-Performance Color Filter Free Image Sensor

Organic photodiodes (OPDs), based on organic semiconductors with high absorption coefficients for visible light, are emerging as potential candidates for replacing silicon photodiodes in image sensors, particularly due to the possibility of realizing a thin thickness and exclusion of color filters, both of which can contribute to a dramatically enhanced degree of integration for image sensors. Despite years of research, techniques have not yet been developed that allow the OPD itself to have color selectivity while maintaining a thin (<1 μm) OPD thickness, in combination with a sufficiently high detectivity (>10¹² cm·Hz^0.5/W). To solve this issue, we introduce a concept of "etalon-electrode", which can perform the function of electrode and simultaneously the function of selective wavelength transparency. A strategically designed OPD architecture consisting of an etalon-electrode, a panchromatic organic active layer, and a counter electrode displays well-defined narrowband R-/G-/B-selective detectivity spectra depending on precision-adjusted thickness composition of the etalon-electrode. While a thin thickness of OPD is preserved at less than 800 nm including electrodes, active layer, and other buffer layers for all R-/G-/B-selective OPDs, high average detectivity values over 10¹² cm·Hz^0.5/W are demonstrated. Furthermore, the characteristic of imparting color selectivity by the etalon-electrode enables a more facile full color patterning, such that a prototype of a 10 × 10 image sensor with a pixel pitch of 500 μm is realized, resulting in accurate picturing of a well-defined full color image.

Facile Synthesis of γ-In2 Se3 Nanoflowers toward High Performance Self-Powered Broadband γ-In2 Se3 /Si Heterojunction Photodiode

An effective colloidal process involving the hot-injection method is developed to synthesize uniform nanoflowers consisting of 2D γ-In₂ Se₃ nanosheets. By exploiting the narrow direct bandgap and high absorption coefficient in the visible light range of In₂ Se₃ , a high-quality γ-In₂ Se₃ /Si heterojunction photodiode is fabricated. This photodiode shows a high photoresponse under light illumination, short response/recovery times, and long-term durability. In addition, the γ-In₂ Se₃ /Si heterojunction photodiode is self-powered and displays a broadband spectral response ranging from UV to IR with a high responsivity and detectivity. These excellent performances make the γ-In₂ Se₃ /Si heterojunction very interesting as highly efficient photodetectors.

Topological Crystalline Insulator SnTe/Si Vertical Heterostructure Photodetectors for High-Performance Near-Infrared Detection

Due to the gapless surface state and narrow bulk band gap, the light absorption of topological crystalline insulators covers a broad spectrum ranging from terahertz to infrared, revealing promising applications in new generation optoelectronic devices. To date, the photodetectors based on topological insulators generally suffer from a large dark current and a weaker photocurrent especially under the near-infrared lights, which severely limits the practical application of devices. Owing to the lower excitation energy of infrared lights, the photodetection application of topological crystalline insulators in the near-infrared region relies critically on understanding the preparation and properties of their heterostructures. Herein, we fabricate the high-quality topological crystalline insulator SnTe film/Si vertical heterostructure by a simple physical vapor deposition process. The resultant heterostructure exhibits an excellent diode characteristic, enabling the construction of high-performance near-infrared photodetectors. The built-in electric field at SnTe/Si interface enhances the absorption efficiency of near-infrared lights and greatly facilitates the separation of photogenerated carriers, making the device capable of operating as a self-driven photodetector. The as-grown SnTe film acts as the hole transport layer in heterostructure photodetectors, promoting the transport of holes to electrode and reducing electron-hole recombination effectively. These merits enable the SnTe/Si heterostructure photodetector to have a high responsivity of 2.36 AW^-1, a high detectivity of 1.54 × 10¹⁴ Jones, and a large bandwidth of 10⁴ Hz in the near-infrared wavelength, which makes the detector have a promising market in novel device applications.

Tuning Carrier Tunneling in van der Waals Heterostructures for Ultrahigh Detectivity

Semiconducting transition metal dichalcogenides (TMDs) are promising materials for photodetection over a wide range of visible wavelengths. Photodetection is generally realized via a phototransistor, photoconductor, p-n junction photovoltaic device, and thermoelectric device. The photodetectivity, which is a primary parameter in photodetector design, is often limited by either low photoresponsivity or a high dark current in TMDs materials. Here, we demonstrated a highly sensitive photodetector with a MoS₂/h-BN/graphene heterostructure, by inserting a h-BN insulating layer between graphene electrode and MoS₂ photoabsorber, the dark-carriers were highly suppressed by the large electron barrier (2.7 eV) at the graphene/h-BN junction while the photocarriers were effectively tunneled through small hole barrier (1.2 eV) at the MoS₂/h-BN junction. With both high photocurrent/dark current ratio (>10⁵) and high photoresponsivity (180 AW^-1), ultrahigh photodetectivity of 2.6 × 10¹³ Jones was obtained at 7 nm thick h-BN, about 100-1000 times higher than that of previously reported MoS₂-based devices.

Passivated Single-Crystalline CH3NH3PbI3 Nanowire Photodetector with High Detectivity and Polarization Sensitivity

Photodetectors convert light signals into current or voltage outputs and are widely used for imaging, sensing, and spectroscopy. Perovskite-based photodetectors have shown high sensitivity and fast response due to the unprecedented low recombination loss in this solution processed semiconductor. Among various types of CH₃NH₃PbI₃ morphology (film, single crystal, nanowire), single-crystalline CH₃NH₃PbI₃ nanowires are particularly interesting for photodetection because of their reduced grain boundary, morphological anisotropy, and excellent mechanical flexibility. The concomitant disadvantage associated with the CH₃NH₃PbI₃ nanowire photodetectors is their large surface area, which catalyzes carrier recombination and material decomposition, thus significantly degrading device performance and stability. Here we solved this key problem by introducing oleic acid soaking to passivate surface defects of CH₃NH₃PbI₃ nanowires, which leads to a device with much improved stability and unprecedented sensitivity (measured detectivity of 2 × 10¹³ Jones). By taking advantage of their one-dimensional geometry, we also showcased, for the first time, the linear dichroic photodetection of our CH₃NH₃PbI₃ nanowire photodetector.

Room-Temperature Solution-Processed NiOx:PbI2 Nanocomposite Structures for Realizing High-Performance Perovskite Photodetectors

While methylammonium lead iodide (MAPbI3) with interesting properties, such as a direct band gap, high and well-balanced electron/hole mobilities, as well as long electron/hole diffusion length, is a potential candidate to become the light absorbers in photodetectors, the challenges for realizing efficient perovskite photodetectors are to suppress dark current, to increase linear dynamic range, and to achieve high specific detectivity and fast response speed. Here, we demonstrate NiOx:PbI2 nanocomposite structures, which can offer dual roles of functioning as an efficient hole extraction layer and favoring the formation of high-quality MAPbI3 to address these challenges. We introduce a room-temperature solution process to form the NiOx:PbI2 nanocomposite structures. The nanocomposite structures facilitate the growth of the compact and ordered MAPbI3 crystalline films, which is essential for efficient photodetectors. Furthermore, the nanocomposite structures work as an effective hole extraction layer, which provides a large electron injection barrier and favorable hole extraction as well as passivates the surface of the perovskite, leading to suppressed dark current and enhanced photocurrent. By optimizing the NiOx:PbI2 nanocomposite structures, a low dark current density of 2 × 10(-10) A/cm(2) at -200 mV and a large linear dynamic range of 112 dB are achieved. Meanwhile, a high responsivity in the visible spectral range of 450-750 nm, a large measured specific detectivity approaching 10(13) Jones, and a fast fall time of 168 ns are demonstrated. The high-performance perovskite photodetectors demonstrated here offer a promising candidate for low-cost and high-performance near-ultraviolet-visible photodetection.