High‐Performance Near‐IR Photodetector Using Low‐Bandgap MA0.5FA0.5Pb0.5Sn0.5I3 Perovskite

Photodetectors with ultrafast response are explored using inorganic/organic hybrid perovskites. High responsivity and fast optoelectronic response are achieved due to the exceptional semiconducting properties of perovskite materials. However, most of the perovskite‐based photodetectors exploited to date are centered on Pb‐based perovskites, which only afford spectral response across the visible spectrum. This study demonstrates a high‐performance near‐IR (NIR) photodetector using a stable low‐bandgap Sn‐containing perovskite, (CH₃NH₃)_0.5(NH₂CHNH₂)_0.5Pb_0.5Sn_0.5I₃ (MA_0.5FA_0.5Pb_0.5Sn_0.5I₃), which is processed with an antioxidant additive, ascorbic acid (AA). The addition of AA effectively strengthens the stability of Sn‐containing perovskite against oxygen, thereby significantly inhibiting the leakage current. Consequently, the derived photodetector shows high responsivity with a detectivity of over 10¹² Jones ranging from 800 to 970 nm. Such low‐cost, solution processable NIR photodetectors with high performance show promising potential for future optoelectronic applications.     

MoS2/Si Heterojunction with Vertically Standing Layered Structure for Ultrafast,High‐Detectivity,Self‐Driven Visible–Near Infrared Photodetectors

As an interesting layered material, molybdenum disulfide (MoS₂) has been extensively studied in recent years due to its exciting properties. However, the applications of MoS₂ in optoelectronic devices are impeded by the lack of high‐quality p–n junction, low light absorption for mono‐/multilayers, and the difficulty for large‐scale monolayer growth. Here, it is demonstrated that MoS₂ films with vertically standing layered structure can be deposited on silicon substrate with a scalable sputtering method, forming the heterojunction‐type photodetectors. Molecular layers of the MoS₂ films are perpendicular to the substrate, offering high‐speed paths for the separation and transportation of photo‐generated carriers. Owing to the strong light absorption of the relatively thick MoS₂ film and the unique vertically standing layered structure, MoS₂/Si heterojunction photodetectors with unprecedented performance are actualized. The self‐driven MoS₂/Si heterojunction photodetector is sensitive to a broadband wavelength from visible light to near‐infrared light, showing an extremely high detectivity up to ≈10¹³ Jones (Jones = cm Hz^1/2 W^?1), and an ultrafast response speed of ≈3 μs. The performance is significantly better than the photodetectors based on mono‐/multilayer MoS₂ nanosheets. Additionally, the MoS₂/Si photodetectors exhibit excellent stability in air for a month. This work unveils the great potential of MoS₂/Si heterojunction for optoelectronic applications.     

Enhanced On–Off Ratio Photodetectors Based on Lead‐Free Cs3Bi2I9 Single Crystal Thin Films

Hybrid organic–inorganic lead halide perovskite single crystal thin film (SCTF) recently has attracted enormous interest in the field of optoelectronic devices, since it efficiently resolves the trade‐off between thickness and carrier diffusion length. However, the toxicity of lead element and the instability induced by organic component still hinder its future developments. In this work, lead‐free all‐inorganic Cs₃Bi₂I₉ SCTF with a high orientation along (00h) has been in situ grown on indium tin oxide (ITO) glass via a space‐limited solvent evaporation crystallization method. The trap density of Cs₃Bi₂I₉ SCTF (5.7 × 10¹² cm^?3) is 263 folds lower than that of the polycrystalline thin film (PCTF) counterpart, together with a 5‐order‐of‐magnitude higher carrier mobility. These superior charge transfer properties enable a photoresponse on–off ratio as high as 11 000, which far surpasses that of the PCTF device by 460 folds, comparable to the lead halide perovskite. Furthermore, the Cs₃Bi₂I₉ SCTF photodetector exhibits outstanding stability even without any encapsulation, whose initial performance is well maintained after aging 1000 h in humid air of 50% RH or continuous on–off light illumination for 20 h. This work will pave the way to produce new families of high‐performance, stable, and nontoxic perovskite SCTF for future optoelectronic applications.     

Controlled Doping of Wafer‐Scale PtSe2 Films for Device Application

Semiconductive transition metal dichalcogenides (TMDs) have been considered as next generation semiconductors, but to date most device investigations are still based on microscale exfoliation with a low yield. Wafer scale growth of TMDs has been reported but effective doping approaches remain challenging due to their atomically thick nature. This work reports the synthesis of wafer‐scale continuous few‐layer PtSe₂ films with effective doping in a controllable manner. Chemical component analyses confirm that both n‐doping and p‐doping can be effectively modulated through a controlled selenization process. The electrical properties of PtSe₂ films have been systematically studied by fabricating top‐gated field effect transistors (FETs). The device current on/off ratio is optimized in two‐layer PtSe₂ FETs, and four‐terminal configuration displays a reasonably high effective field effect mobility (14 and 15 cm² V^?1 s^?1 for p‐type and n‐type FETs, respectively) with a nearly symmetric p‐type and n‐type performance. Temperature dependent measurement reveals that the variable range hopping is dominant at low temperatures. To further establish feasible application based on controllable doping of PtSe₂, a logic inverter and vertically stacked p–n junction arrays are demonstrated. These results validate that PtSe₂ is a promising candidate among the family of TMDs for future functional electronic applications.     

Few‐Layered PtS2 Phototransistor on h‐BN with High Gain

The very recently rediscovered group‐10 transition metal dichalcogenides (TMDs) such as PtS₂ and PtSe₂, have joined the 2D material family as potentially promising candidates for electronic and optoeletronic applications due to their theoretically high carrier mobility, widely tunable bandgap, and ultrastability. Here, the first exploration of optoelectronic application based on few‐layered PtS₂ using h‐BN as substrate is presented. The phototransistor exhibits high responsivity up to 1.56 × 10³ A W^?1 and detectivity of 2.9 × 10¹¹ Jones. Additionally, an ultrahigh photogain ≈2 × 10⁶ is obtained at a gate voltage V _g = 30 V, one of the highest gain among 2D photodetectors, which is attributed to the existence of trap states. More interestingly, the few‐layered PtS₂ phototransistor shows a back gate modulated photocurrent generation mechanism, that is, from the photoconductive effect dominant to photogating effect dominant via tuning the gate voltage from the OFF state to the ON state. Such good properties combined with gate‐controlled photoresponse of PtS₂ make it a competitive candidate for future 2D optoelectronic applications.     

Single‐Crystalline p‐Type Zn3As2 Nanowires for Field‐Effect Transistors and Visible‐Light Photodetectors on Rigid and Flexible Substrates

Zn₃As₂ is an important p‐type semiconductor with the merit of high effective mobility. The synthesis of single‐crystalline Zn₃As₂ nanowires (NWs) via a simple chemical vapor deposition method is reported. High‐performance single Zn₃As₂ NW field‐effect transistors (FETs) on rigid SiO₂/Si substrates and visible‐light photodetectors on rigid and flexible substrates are fabricated and studied. As‐fabricated single‐NW FETs exhibit typical p‐type transistor characteristics with the features of high mobility (305.5 cm² V^?1 s^?1) and a high I_on/I_off ratio (10⁵). Single‐NW photodetectors on SiO₂/Si substrate show good sensitivity to visible light. Using the contact printing process, large‐scale ordered Zn₃As₂ NW arrays are successfully assembled on SiO₂/Si substrate to prepare NW thin‐film transistors and photodetectors. The NW‐array photodetectors on rigid SiO₂/Si substrate and flexible PET substrate exhibit enhanced optoelectronic performance compared with the single‐NW devices. The results reveal that the p‐type Zn₃As₂ NWs have important applications in future electronic and optoelectronic devices.     

Inch‐Size Single Crystal of a Lead‐Free Organic–Inorganic Hybrid Perovskite for High‐Performance Photodetector

Large‐size crystals of organic–inorganic hybrid perovskites (e.g., CH₃NH₃PbX₃, X = Cl, Br, I) have gained wide attention since their spectacular progress on optoelectronic technologies. Although presenting brilliant semiconducting properties, a serious concern of the toxicity in these lead‐based hybrids has become a stumbling block that limits their wide‐scale applications. Exploring lead‐free hybrid perovskite is thus highly urgent for high‐performance optoelectronic devices. Here, a new lead‐free perovskite hybrid (TMHD)BiBr₅ (TMHD = N,N,N,N‐tetramethyl‐1,6‐hexanediammonium) is prepared from facile solution process. Emphatically, inch‐size high‐quality single crystals are successfully grown, the dimensions of which reach up to 32 × 24 × 12 mm³. Furthermore, the planar arrays of photodetectors based on bulk lead‐free (TMHD)BiBr₅ single crystals are first fabricated, which shows sizeable on/off current ratios (≈10³) and rapid response speed (τ_rise = 8.9 ms and τ_decay = 10.2 ms). The prominent device performance of (TMHD)BiBr₅ strongly underscores the lead‐free hybrid perovskite single crystals as promising material candidates for optoelectronic applications.     

Large‐Area Bilayer ReS2 Film/Multilayer ReS2 Flakes Synthesized by Chemical Vapor Deposition for High Performance Photodetectors

Rhenium disulfide (ReS₂) is attracting more and more attention for its thickness‐depended direct band gap. As a new appearing 2D transition metal dichalcogenide, the studies on synthesis method via chemical vapor deposition (CVD) is still rare. Here a systematically study on the CVD growth of continuous bilayer ReS₂ film and single crystalline hexagonal ReS₂ flake, as well as their corresponding optoelectronic properties is reported. Moreover, the growth mechanism has been proposed, accompanied with simulation study. High‐performance photodetector based on ReS₂ flake shows a high responsivity of 604 A·W^?1, high external quantum efficiency of 1.50 × 10⁵ %, and fast response time of 2 ms. ReS₂ film‐based photodetector exhibits weaker performance than the flake one; however, it still demonstrates a much faster response time (≈10³ ms) than other reported CVD‐grown ReS₂‐based photodetector (≈10⁴–10⁵ ms). Such good properties of ReS₂ render it a promising future in 2D optoelectronics.     

Synthesis of Large‐Area Atomically Thin BiOI Crystals with Highly Sensitive and Controllable Photodetection

Compared to the most studied 2D elements and binary compounds, ternary layered compounds with more adjustable physical and chemical properties have exhibited potential applications in electronic and optoelectronic devices. Here, 2D ternary layered BiOI crystals are synthesized first with a domain size up to 100 µm via space‐confined chemical vapor deposition. The photodetectors based on the as‐grown BiOI nanosheets demonstrate high sensitivity to 473 nm light. The I_on/I_off ratio and detectivity of BiOI photodetectors can reach up to 1 × 10⁵ and 8.2 × 10¹¹ Jones at 473 nm, respectively. Particularly, the contact and dark current of the photodetectors can be controlled by 254 nm ultraviolet light irradiation due to the introduction of oxygen vacancies. The facile synthesis of large‐area atomically thin BiOI and its controllable performance by ultraviolet light irradiation suggest that 2D BiOI crystal is a promising material for fundamental investigations and optoelectronic applications.     

Water‐Induced Scandium Oxide Dielectric for Low‐Operating Voltage n‐ and p‐Type Metal‐Oxide Thin‐Film Transistors

Solution‐processed metal‐oxide thin films based on high dielectric constant (k) materials have been extensively studied for use in low‐cost and high‐performance thin‐film transistors (TFTs). Here, scandium oxide (ScO_x) is fabricated as a TFT dielectric with excellent electrical properties using a novel water‐inducement method. The thin films are annealed at various temperatures and characterized by using X‐ray diffraction, atomic‐force microscopy, X‐ray photoelectron spectroscopy, optical spectroscopy, and a series of electrical measurements. The optimized ScO_x thin film exhibits a low‐leakage current density of 0.2 nA cm^?2 at 2 MV cm^?1, a large areal capacitance of 460 nF cm^?2 at 20 Hz and a permittivity of 12.1. To verify the possible applications of ScO_x thin films as the gate dielectric in complementary metal oxide semiconductor (CMOS) electronics, they were integrated in both n‐type InZnO (IZO) and p‐type CuO TFTs for testing. The water‐induced full oxide IZO/ScO_x TFTs exhibit an excellent performance, including a high electron mobility of 27.7 cm² V^?1 s^?1, a large current ratio (I_on/I_off) of 2.7 × 10⁷ and high stability. Moreover, as far as we know it is the first time that solution‐processed p‐type oxide TFTs based on a high‐k dielectric are achieved. The as‐fabricated p‐type CuO/ScO_x TFTs exhibit a large I_on/I_off of around 10⁵ and a hole mobility of 0.8 cm² V^?1 at an operating voltage of 3 V. To the best of our knowledge, these electrical parameters are among the highest performances for solution‐processed p‐type TFTs, which represents a great step towards the achievement of low‐cost, all‐oxide, and low‐power consumption CMOS logics.     

Submillimeter 2D Bi2Se3 Flakes toward High‐Performance Infrared Photodetection at Optical Communication Wavelength

Infrared detection at optical communication wavelength is of great significance because of their diverse commercial and military communication applications. The layered Bi₂Se₃ with a narrow band gap of 0.3 eV is regarded as a promising candidate toward high‐performance terahertz to infrared applications. However, the controllable synthesis of large‐size ultrathin Bi₂Se₃ flakes remains a challenge owing to complex nucleation process and infrared telecommunication photodetectors based on Bi₂Se₃ flakes are rarely reported. Here, large size (submillimeter: 0.2–0.4 mm in lateral dimensions) and ultrathin (thickness: 3 nm to few nanometers) 2D Bi₂Se₃ flakes with high crystal quality are obtained by suppressing the nucleation density. More importantly, back‐gate field‐effect transistor based on Bi₂Se₃ flake exhibits an ultrahigh on/off current ratio of 10⁶ and competitive mobility of 39.4 cm² V^?1 s^?1. Moreover, excellent on/off ratio of 972.5, responsivity of 23.8 A W^?1, and external quantum efficiency of 2035% are obtained from Bi₂Se₃‐based photodetector at 1456 nm in the E‐band of the telecommunication range. With controlled morphology and excellent photoresponse performance, the Bi₂Se₃ photodetector shows great potential in the optoelectronic field including communications, military, and remote sensing.     

Novel Ω‐Shaped Core–Shell Photodetector with High Ultraviolet Selectivity and Enhanced Responsivity

The design of nanostructure plays an important role in performance enhancement of low‐dimensional optoelectronic devices. Herein, a novel photodetector (PD) based on electrospun SnO₂ nanofibers with Ω‐shaped ZnO shell (SnO₂@ZnO) is fabricated. With 87.4% transmittance at 550 nm, SnO₂@ZnO PD exhibits a high photo‐to‐dark current ratio up to 10⁴ at around 280 nm. Owing to the additional Ω‐shaped ZnO shell, SnO₂@ZnO PD possesses a responsivity of nearly 100 A W^?1 under 5 V bias and the illumination of 250 nm light, which is 30‐time enhancement of pristine SnO₂ PD. The enhancement is mainly attributed to type‐II energy band structure. Furthermore, by changing the direction of incident light, SnO₂@ZnO PD has a high UV selectivity with an UV–vis rejection ratio (R _{250 nm}/R _{400 nm}) as much as 2.0 × 10³ at 5 V bias under back illumination, which is fourfold higher than that under face illumination. The UV selectivity improvement may be attributed to light confinement in the Ω‐shaped structure. With both theoretical simulations and experimental comparisons, it is demonstrated that the unique compact Ω‐shaped nanostructure does contribute to photon trapping and gaining process, especially in back‐illumination configuration. The approach can be easily extended to other materials, preparing novel building blocks for optoelectronic devices.     

High‐Performance Ferroelectric Polymer Side‐Gated CdS Nanowire Ultraviolet Photodetectors

An efficient ferroelectric‐enhanced side‐gated single CdS nanowire (NW) ultraviolet (UV) photodetector at room temperature is demonstrated. With the ultrahigh electrostatic field from polarization of ferroelectric polymer, the depletion of the intrinsic carriers in the CdS NW channel is achieved, which significantly reduces the dark current and increases the sensitivity of the UV photodetector even after the gate voltage is removed. Meanwhile, the low frequency noise current power of the device reaches as low as 4.6 × 10^?28 A² at a source‐drain voltage V_ds = 1 V. The single CdS NW UV photodetector exhibits high photoconductive gain of 8.6 × 10⁵, responsivity of 2.6 × 10⁵ A W^?1, and specific detectivity (D*) of 2.3 × 10¹⁶ Jones at a low power density of 0.01 mW cm^?2 for λ = 375 nm. In addition, the spatially resolved scanning photocurrent mapping across the device shows strong photocurrent signals near the metal contacts. This is promising for the design of a controllable, high‐performance, and low power consumption ultraviolet photodetector.     

Facet‐Dependent,Fast Response,and Broadband Photodetector Based on Highly Stable All‐Inorganic CsCu2I3 Single Crystal with 1D Electronic Structure

Low‐dimensional metal halides at molecular level, which feature strong quantum confinement effects from intrinsic structure, are emerging as ideal candidates in optoelectronic fields. However, developing stable and nontoxic metal halides still remains a great challenge. Herein, for the first time, high‐crystalline and highly stable CsCu₂I₃ single crystal, which is acquired by a low‐cost antisolvent vapor assisted method, is successfully developed to construct high‐speed (t_rise/t_decay = 0.19 ms/14.7 ms) and UV‐to‐visible broadband (300–700 nm) photodetector, outperforming most reported photodetectors based on individual all‐inorganic lead‐free metal halides. Intriguingly, facet‐dependent photoresponse is observed for CsCu₂I₃ single crystal, whose morphology consists of {010}, {110}, and {021} crystal planes. The on–off ratio of {010} crystal plane is higher than that of {110} crystal plane, mainly owing to lower dark current. Furthermore, photogenerated electrons are localized in twofold chains created by [CuI₄] tetrahedra, leading to relatively small effective mass and fast transport mobility along the 1D transport pathway. Anisotropic carrier transport characteristic is related to stronger confinement and higher electron density for {110} crystal planes. This work not only demonstrates the great potential of CsCu₂I₃ single crystal in high‐performance optoelectronics, but also gives insights into 1D electronic structure associated with fast photoresponse and high anisotropy.     

Novel and Enhanced Optoelectronic Performances of Multilayer MoS2–WS2 Heterostructure Transistors

Van der Waals heterostructures designed by assembling isolated two‐dimensional (2D) crystals have emerged as a new class of artificial materials with interesting and unusual physical properties. Here, the multilayer MoS₂–WS₂ heterostructures with different configurations are reported and their optoelectronic properties are studied. It is shown that the new heterostructured material possesses new functionalities and superior electrical and optoelectronic properties that far exceed the one for their constituents, MoS₂ or WS₂. The vertical transistor exhibits a novel rectifying and bipolar behavior, and can also act as photovoltaic cell and self‐driven photodetector with photo‐switching ratio exceeding 10³. The planar device also exhibits high field‐effect ON/OFF ratio (>10⁵), high electron mobility of 65 cm²/Vs, and high photo­responsivity of 1.42 A/W compared to that in isolated multilayer MoS₂ or WS₂ nanoflake transistors. The results suggest that formation of MoS₂–WS₂ heterostructures could significantly enhance the performance of optoelectronic devices, thus open up possibilities for future nanoelectronic, photovoltaic, and optoelectronic applications.     

High‐Performance UV–Vis–NIR Phototransistors Based on Single‐Crystalline Organic Semiconductor–Gold Hybrid Nanomaterials

Hybrid materials in optoelectronic devices can generate new functionality or provide synergistic effects that enhance the properties of each component. Here, high‐performance phototransistors with broad spectral responsivity in UV–vis–near‐infrared (NIR) regions, using gold nanorods (Au NRs)‐decorated n‐type organic semiconductor and N ,N ′‐bis(2‐phenylethyl)‐perylene‐3,4:9,10‐tetracarboxylic diimide (BPE‐PTCDI) nanowires (NWs) are reported. By way of the synergistic effect of the excellent photo‐conducting characteristics of single‐crystalline BPE‐PTCDI NW and the light scattering and localized surface plasmon resonances (LSPR) of Au NRs, the hybrid system provides new photo‐detectivity in the NIR spectral region. In the UV–vis region, hybrid nanomaterial‐based phototransistors exhibit significantly enhanced photo‐responsive properties with a photo‐responsivity (R ) of 7.70 × 10⁵ A W^?1 and external quantum efficiency (EQE) of 1.42 × 10⁸% at the minimum light intensity of 2.5 µW cm^?2, which are at least tenfold greater than those of pristine BPE‐PTCDI NW‐based ones and comparable to those of high‐performance inorganic material‐based devices. While a pristine BPE‐PTCDI NW‐based photodetector is insensitive to the NIR spectral region, the hybrid NW‐based phototransistor shows an R of 10.7 A W^?1 and EQE of 1.35 × 10³% under 980 nm wavelength‐NIR illumination. This work demonstrates a viable approach to high‐performance photo‐detecting systems with broad spectral responsivity.     

High‐Performance,Air‐Stable,Top‐Gate,p‐Channel WSe2 Field‐Effect Transistor with Fluoropolymer Buffer Layer

High‐performance, air‐stable, p‐channel WSe₂ top‐gate field‐effect transistors (FETs) using a bilayer gate dielectric composed of high‐ and low‐k dielectrics are reported. Using only a high‐k Al₂O₃ as the top‐gate dielectric generally degrades the electrical properties of p‐channel WSe₂, therefore, a thin fluoropolymer (Cytop) as a buffer layer to protect the 2D channel from high‐k oxide forming is deposited. As a result, a top‐gate‐patterned 2D WSe₂ FET is realized. The top‐gate p‐channel WSe₂ FET demonstrates a high hole mobility of 100 cm²_­ V^?1 s^?1 and a I_ON/I_OFF ratio > 10⁷ at low gate voltages (V_GS ca. ?4 V) and a drain voltage (V_DS) of ?1 V on a glass substrate. Furthermore, the top‐gate FET shows a very good stability in ambient air with a relative humidity of 45% for 7 days after device fabrication. Our approach of creating a high‐k oxide/low‐k organic bilayer dielectric is advantageous over single‐layer high‐k dielectrics for top‐gate p‐channel WSe₂ FETs, which will lead the way toward future electronic nanodevices and their integration.     

Large‐Size Growth of Ultrathin SnS2 Nanosheets and High Performance for Phototransistors

2D SnS₂ nanosheets have been attracting intensive attention as one potential candidate for the modern electronic and/or optoelectronic fields. However, the controllable large‐size growth of ultrathin SnS₂ nanosheets still remains a great challenge and the photodetectors based on SnS₂ nanosheets suffer from low responsivity, thus hindering their further applications so far. Herein, an improved chemical vapor deposition route is provided to synthesize large‐size SnS₂ nanosheets, the side length of which can surpass 150 μm. Then, ultrathin SnS₂ nanosheet‐based phototransistors are fabricated, which achieve high photoresponsivities up to 261 A W^?1 (with a fast rising time of 20 ms and a falling time of 16 ms) in air and 722 A W^?1 in vacuum, respectively. Furthermore, the effects of back‐gate voltage and air adsorbates on the optoelectronic properties of the SnS₂ nanosheet have been systematically investigated. In addition, a high‐performance flexible photodetector based on SnS₂ nanosheet is also fabricated with a high responsivity of 34.6 A W^?1.     

Autogenous Growth of Hierarchical NiFe(OH)x/FeS Nanosheet‐On‐Microsheet Arrays for Synergistically Enhanced High‐Output Water Oxidation

Practical electrochemical water splitting requires cost‐effective electrodes capable of steadily working at high output, leading to the challenges for efficient and stable electrodes for the oxygen evolution reaction (OER). Herein, by simply using conductive FeS microsheet arrays vertically pre‐grown on iron foam (FeS/IF) as both substrate and source to in situ form vertically aligned NiFe(OH)_x nanosheets arrays, a hierarchical electrode with a nano/micro sheet‐on‐sheet structure (NiFe(OH)_x/FeS/IF) can be readily achieved to meet the requirements. Such hierarchical electrode architecture with a superhydrophilic surface also allows for prompt gas release even at high output. As a result, NiFe(OH)_x/FeS/IF exhibits superior OER activity with an overpotential of 245 mV at 50 mA cm^?2 and can steadily output 1000 mA cm^?2 at a low overpotential of 332 mV. The water‐alkali electrolyzer using NiFe(OH)_x/FeS/IF as the anode can deliver 10 mA cm^?2 at 1.50 V and steadily operate at 300 mA cm^?2 with a small cell voltage for 70 h. Furthermore, a solar‐driven electrolyzer using the developed electrode demonstrates an exceptionally high solar‐to‐hydrogen efficiency of 18.6%. Such performance together with low‐cost Fe‐based materials and facile mass production suggest the present strategy may open up opportunities for rationally designing hierarchical electrocatalysts for practical water splitting or diverse applications.     

All‐Polymer Bistable Resistive Memory Device Based on Nanoscale Phase‐Separated PCBM‐Ferroelectric Blends

All polymer nonvolatile bistable memory devices are fabricated from blends of ferroelectric poly(vinylidenefluoride–trifluoroethylene (P(VDF‐TrFE)) and n‐type semiconducting [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). The nanoscale phase separated films consist of PCBM domains that extend from bottom to top electrode, surrounded by a ferroelectric P(VDF‐TrFE) matrix. Highly conducting poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer electrodes are used to engineer band offsets at the interfaces. The devices display resistive switching behavior due to modulation of this injection barrier. With careful optimization of the solvent and processing conditions, it is possible to spin cast very smooth blend films (R_rms ≈ 7.94 nm) and with good reproducibility. The devices exhibit high I_on/I_off ratios (≈3 × 10³), low read voltages (≈5 V), excellent dielectric response at high frequencies (?_r ≈ 8.3 at 1 MHz), and excellent retention characteristics up to 10 000 s.