Multifunctional Optoelectronic Devices Research Articles

In Situ Synthesis of CsPbX3/Polyacrylonitrile Nanofibers with Water-Stability and Color-Tunability for Anti-Counterfeiting and LEDs.

Inorganic CsPbX3 (X = Cl, Br, I) perovskite quantum dots (PQDs) have attracted widespread attention due to their excellent optical properties and extensive application prospects. However, their inherent structural instability significantly hinders their practical application despite their outstanding optical performance. To enhance stability, an in situ electrospinning strategy was used to synthesize CsPbX3/polyacrylonitrile composite nanofibers. By optimizing process parameters (e.g., halide ratio, electrospinning voltage, and heat treatment temperature), all-inorganic CsPbX3 PQDs have been successfully grown in a polyacrylonitrile (PAN) matrix. During the electrospinning process, the rapid solidification of electrospun fibers not only effectively constrained the formation of large-sized PQDs but also provided effective physical protection for PQDs, resulting in the improvement in the water stability of PQDs by minimizing external environmental interference. Even after storage in water for over 100 days, the PQDs maintained approximately 93.5% of their photoluminescence intensity. Through the adjustment of halogen elements, the as-obtained composite nanofibers exhibited color-tunable luminescence in the visible light region, and based on this, a series of multicolor anti-counterfeiting patterns were fabricated. Additionally, benefiting from the excellent water stability and optical performance, the CsPbBr3/PAN composite film was combined with red-emitting K2SiF6:Mn4+ (KSF) on a blue LED (460 nm), producing a stable and efficient WLED device with a color temperature of around 6000 K and CIE coordinates of (0.318, 0.322). These results provide a general approach to synthesizing PQDs/polymer nanocomposites with excellent water stability and multicolor emission, thereby promoting their practical applications in multifunctional optoelectronic devices and advanced anti-counterfeiting.

Boosting Bidirectional Photoresponse with Wavelength Selectivity through Ambipolar Transport Modulation

AbstractNegative photoconductive phototransistors, referring to transistors that exhibit a decrease in photocurrent under illumination, have the potential to revolutionize optoelectronic applications involving light, such as optoelectronic logic circuits and visual neural simulation. Currently, achieving negative photoconductivity (NPC) requires complex material design or interface structure construction. However, achieving precise control over NPC behaviors poses a significant challenge. Herein, a simple yet effective strategy is demonstrated for realizing controllable NPC responses in organic phototransistors through ambipolar transport modulation. Due to the controversy between the preferred exciton dissociation/charge separation direction and the gate electric field driven charge drift direction, the main semiconductor channel (n‐ or p‐channel) exhibits NPC behavior under illumination. The validity of this mechanism has been confirmed through intensive studies by varying the component and combination of the p‐n heterostructure. Moreover, devices utilizing ambipolar transport exhibit a wavelength‐selectivity NPC response due to the absorption characteristics of the combined semiconductor materials. Most encouragingly, by incorporating both negative and positve photoconductivity along with wavelength‐selective responses, high‐contrast image sensing, information encryption and decryption, as well as optoelectronic logic circuit design is successfully achieved. This work promotes the design and development of bidirectional optoelectronic devices and offers a new route for developing attractive multifunctional optoelectronic devices.

β-Ga2O3 van der Waals p-n homojunction

The van der Waals (vdW) p-n junctions are crucial to develop multifunctional and high-performance electronic and optoelectronic devices. The asymmetric doping effect in wide-bandgap (WBG) semiconductors poses a fundamental obstacle for fabricating the vdW p-n homojunction and impedes the development of full WBG semiconductors-based bipolar devices. In this study, we demonstrate the β-Ga2O3 vdW p-n homojunctions with 2.0 nm-thick vdW gap, 2.6 eV built-in potential and 1.5 μm-wide depletion region, via combining quasi-two-dimensional n-type β-Ga2O3 nanosheets with p-type β-Ga2O3 films. Various tunneling transports including direct tunneling, Fowler-Nordheim tunneling, and exciton-assisted tunnelling are observed and explored in detail. The β-Ga2O3 vdW p-n homojunction diodes possess high forward current density (3.0 × 10−3 A/cm2), extremely-low reverse leakage current density (3.0 × 10−9 A/cm2), high rectification ratio (106 under dark and 107 under illumination), high photoresponsivity (13.4 A/W) and detectivity (9.38 × 1013 Jones) at 10 V bias under 250 nm illumination, and narrowband detection for the deep-ultraviolet solar-blind spectral region. This work lays the foundation for β-Ga2O3 homogeneous bipolar vdW devices and paves the way to advance the next-generation electronic and optoelectronic multifunctional devices based on the vdW integration.

Perovskite/organic tandem device to realize light detection and emission dual function

Developing highly integrated smart optoelectronic systems is vital to modern technology, yet critically challenging. This study introduces a tandem device that incorporates an organic photodiode (OPD) and a perovskite light emitting diode (PeLED), enabling simultaneous light detection and emission in one compact device, prepared by all-solution fabrication process. It shows that precise control of interfacial properties plays a critical role in establishing the all-solution processed OPD/PeLED multi-layered dual-function device which is critical for charge transport, recombination, and generation. The integrated structure allows for light detection and emission function selectively by controlling the polarity of the external bias. The optoelectronic performance of the dual-function tandem device is comparable to that of the discrete control OPD and PeLED, i.e., the tandem device achieves a responsivity of 94 mA/W at 850 nm under −1 V and a luminance result of 1319 cd/m2 at 516 nm under 7 V, which is comparable to 101 mA/W and 1983 cd/m2 for the control OPD and PeLED operated under the same conditions. This work demonstrates the promising properties of the monolithically integrated dual-functional device and its potential for application in health monitoring and wearable electronic devices.

Gate Voltage- and Bias Voltage-Tunable Staggered-Gap to Broken-Gap Transition Based on WSe2/Ta2NiSe5 Heterostructure for Multimode Optoelectronic Logic Gate.

Two-dimensional (2D) materials with superior properties exhibit tremendous potential in developing next-generation electronic and optoelectronic devices. Integrating various functions into one device is highly expected as that endows 2D materials great promise for more Moore and more-than-Moore device applications. Here, we construct a WSe2/Ta2NiSe5 heterostructure by stacking the p-type WSe2 and the n-type narrow gap Ta2NiSe5 with the aim to achieve a multifunction optoelectronic device. Owing to the large interface potential barrier, the heterostructure device reveals a prominent diode feature with a large rectify ratio (7.6 × 104) and a low dark current (10-12 A). Especially, gate voltage- and bias voltage-tunable staggered-gap to broken-gap transition is achieved on the heterostructure device, which enables gate voltage-tunable forward and reverse rectifying features. As results, the heterostructure device exhibits superior self-powered photodetection properties, including a high detectivity of 1.08 × 1010 Jones and a fast response time of 91 μs. Additionally, the intrinsic structural anisotropy of Ta2NiSe5 endows the heterostructure device with strong polarization-sensitive photodetection and high-resolution polarization imaging. Based on these characteristics, a multimode optoelectronic logic gate is realized on the heterostructure via synergistically modulating the light on/off, polarization angle, gate voltage, and bias voltage. This work shed light on the future development of constructing high-performance multifunctional optoelectronic devices.

Multifunctional Phototransistor Based on Double Van der Waals Heterojunction with Reversed Band Edge Bending

AbstractDouble van der Waals heterojunctions (vdWHs) based on 2D materials showcase multifunctional properties, including anti‐ambipolar behavior and polarization‐sensitive photodetection capabilities, providing a new degree of freedom for the development of next‐generation integrated electronics and optoelectronics. Herein, this work reports an anti‐ambipolar transistor with high polarized photosensitivity based on MoS2/Ta2NiS5/WSe2 double vdWH with back‐to‐back type‐I band alignment. It demonstrates a noticeable negative differential transconductance with an ultrahigh peak‐to‐valley ratio of 4.3 × 104 and a bidirectional transconductance variation from 41.6 to −17.5 nS when VD = 2 V. It is ascribed to the effective gate‐modulation of the reversed band edge bending at the double vdWH interfaces. Additionally, the structure benefits from a photogating effect and the anisotropic Ta2NiS5 interlayer, achieving a peak responsivity of 120.58 A W−1 and a decent specific detectivity of 2.65 × 1012 Jones at VD = 2 V and Vg = 5 V and exhibiting an exceptional photocurrent anisotropic ratio of 15.31 via the photovoltaic effect under 635 nm light. These findings not only expand the potential applications of the advanced 2D Ta2NiS5 material but also offer valuable insights for the development of multifunctional optoelectronic devices leveraging 2D double vdWHs.

Universal Design and Efficient Synthesis for High Ambipolar Mobility Emissive Conjugated Polymers.

High ambipolar mobility emissive conjugated polymers (HAME-CPs) are perfect candidates for organic optoelectronic devices, such as polymer light emitting transistors. However, due to intrinsic trade-off relationship between high ambipolar mobility and strong solid-state luminescence, the development of HAME-CPs suffers from high structural and synthetic complexity. Herein, a universal design principle and simple synthetic approach for HAME-CPs are developed. A series of simple non-fused polymers composed of charge transfer units, π bridges and emissive units are synthesized via a two-step microwave assisted C-H arylation and direct arylation polymerization protocol with high total yields up to 61 %. The synthetic protocol is verified valid among 7 monomers and 8 polymers. Most importantly, all 8 conjugated polymers have strong solid-state emission with high photoluminescence quantum yields up to 24 %. Furthermore, 4 polymers exhibit high ambipolar field effect mobility up to 10-2 cm2 V-1 s-1, and can be used in multifunctional optoelectronic devices. This work opens a new avenue for developing HAME-CPs by efficient synthesis and rational design.

Universal Design and Efficient Synthesis for High Ambipolar Mobility Emissive Conjugated Polymers

AbstractHigh ambipolar mobility emissive conjugated polymers (HAME‐CPs) are perfect candidates for organic optoelectronic devices, such as polymer light emitting transistors. However, due to intrinsic trade‐off relationship between high ambipolar mobility and strong solid‐state luminescence, the development of HAME‐CPs suffers from high structural and synthetic complexity. Herein, a universal design principle and simple synthetic approach for HAME‐CPs are developed. A series of simple non‐fused polymers composed of charge transfer units, π bridges and emissive units are synthesized via a two‐step microwave assisted C−H arylation and direct arylation polymerization protocol with high total yields up to 61 %. The synthetic protocol is verified valid among 7 monomers and 8 polymers. Most importantly, all 8 conjugated polymers have strong solid‐state emission with high photoluminescence quantum yields up to 24 %. Furthermore, 4 polymers exhibit high ambipolar field effect mobility up to 10−2 cm2 V−1 s−1, and can be used in multifunctional optoelectronic devices. This work opens a new avenue for developing HAME‐CPs by efficient synthesis and rational design.

Switchable Anisotropic/Isotropic Photon Transport in a Double-Dipole Metal-Organic Framework via Radical-Controlled Energy Transfer.

Directional control of photon transport at micro/nanoscale holds great potential in developing multifunctional optoelectronic devices. Here, the switchable anisotropic/isotropic photon transport is reported in a double-dipole metal-organic framework (MOF) based on radical-controlled energy transfer. Double-dipole MOF microcrystals with transition dipole moments perpendicular to each other have been achieved by the pillared-layer coordination strategy. The energy transfer between the double dipolar chromophores can be modulated by the photogenerated radicals, which permits the in situ switchable output on both polarization (isotropy/anisotropy state) and wavelength information (blue/red-color emission). On this basis, the original MOF microcrystal with isotropic polarization state displays the isotropic photon transport and similar reabsorption losses at various directions, while the radical-affected MOF microcrystal with anisotropic polarization state shows the anisotropic photon transport with distinct reabsorption losses at different directions, finally leading to the in situ switchable anisotropic/isotropic photon transport. These results offer a novel strategy for the development of MOF-based photonic devices with tunable anisotropic performance.

Giant Negative Photoresponse in van der Waals Graphene/AgBiP2Se6/Graphene Trilayer Heterostructures.

The positive photoconductive (PPC) effect is a well-established primary detection mechanism employed by photodetectors. In contrast, the negative photoconductive (NPC) effect is not extensively investigated thus far, and research on the NPC effect is still in its early stage. Herein, a quaternary van der Waals material, AgBiP2Se6 atomic layers, is discovered to achieve a giant NPC effect. Through experimental observations in a Graphene/AgBiP2Se6/ Graphene-based vertical photodetector, an irreversible conversion is identified from common PPC photoresponse to atypical NPC photoresponse. Notably, this device demonstrates an exceptionally high negative responsivity (R) of 4.9×105AW-1, surpassing the previous records for NPC photodetectors. Additionally, it exhibits remarkable optoelectronic performances, including an external quantum efficiency of 1.3×108% and a detectivity (D) of 3.60×1012Jones. The exceptionally high NPC photoresponse observed in this device can be attributed to the swift suppression of photogenerated free carriers at robust recombination centers situated at significant depths, induced by the elevated drain-source voltage bias. The remarkably high NPC photoresponse also positions AgBiP2Se6 as a promising 2D material for multifunctional optoelectronic devices and an excellent platform for systematic exploration of the NPC effect.

Gate‐Tunable Spectral Response in β‐Ga2O3/Te Hybrid Photogating Structure for Ultrasensitive Broadband Detection

AbstractThe increasing demand for multispectral information acquisition and the complexity of application environments have sparked a growing interest in broadband detection. However, achieving a high level of responsivity across a wide response range remains a significant challenge. Herein, an ultrasensitive broadband phototransistor based on hybrid photogating (HPG) structure is demonstrated, which consisted of a quasi‐2D beta‐phase gallium oxide (β‐Ga2O3) nanoflake as the carrier transport channel and a tellurium (Te) nanoflake as the photogating layer. Attributed to the strong doping influence of the Te nanoflake, a low off‐state current of pA level and a high on/off current ratio of ≈108 are obtained. Upon 255 nm wavelength illumination, the device exhibited an ultrahigh responsivity up to 3.82 × 106 A W−1 and a detectivity as high as 1.59 × 1014 Jones across a large gate voltage range. Notably, an exciting infrared response is obtained with a responsivity of 138 A W−1 and a detectivity of 3.70 × 109 Jones under the 1550 nm wavelength illumination, exclusively achievable when the gate voltage exceeded 4 V. Leveraging the gate‐tunable spectral response, an innovative model for secure optical communication was proposed. This work presents an efficient and feasible strategy for fabricating multifunctional optoelectronic devices.

A high-performance broadband phototransistor array of a PdSe2/SOI Schottky junction.

There is great interest in the incorporation of novel two-dimensional materials into Si-based technologies to realize multifunctional optoelectronic devices via heterogeneous integration. Here, we demonstrate a gate-tunable, self-driven, high-performance broadband phototransistor array based on a PdSe2/Si Schottky junction, which is fabricated by pre-depositing a semi-metallic PdSe2 film on a SOI substrate. In addition, thanks to the zero bandgap of the PdSe2 material and the PdSe2/Si vertical heterostructure, the prepared phototransistor exhibits pronounced photovoltaic properties in a wide spectral range from ultraviolet to near-infrared. The responsivity, specific detectivity and response time of the device at the incident light wavelength of 808 nm are 1.15 A W-1, 9.39 × 1010 Jones, and 27.1/40.3 μs, respectively, which are better than those of previously reported PdSe2-based photodetectors. The photoelectric performance can be further improved by applying an appropriate gate voltage to the phototransistor and the responsivity of the device increases to 1.61 A W-1 at VG = 5 V. We demonstrate the excellent imaging capabilities of a 4 × 4 array image sensor using PdSe2/SOI phototransistors under 375 nm, 532 nm, and 808 nm laser sources.

A multifunctional optoelectronic device based on 2D material with wide bandgap

Low-dimensional materials exhibit unique quantum confinement effects and morphologies as a result of their nanoscale size in one or more dimensions, making them exhibit distinctive physical properties compared to bulk counterparts. Among all low-dimensional materials, due to their atomic level thickness, two-dimensional materials possess extremely large shape anisotropy and consequently are speculated to have large optically anisotropic absorption. In this work, we demonstrate an optoelectronic device based on the combination of two-dimensional material and carbon dot with wide bandgap. High-efficient luminescence of carbon dot and extremely large shape anisotropy (>1500) of two-dimensional material with the wide bandgap of >4 eV cooperatively endow the optoelectronic device with multi-functions of optically anisotropic blue-light emission, visible light modulation, wavelength-dependent ultraviolet-light detection as well as blue fluorescent film assemble. This research opens new avenues for constructing multi-function-integrated optoelectronic devices via the combination of nanomaterials with different dimensions.

Enhanced photoresponse of self-powered ZnO-based photoelectrochemical-type UV photodetectors via Ga-doping for optical communication application

Wide-bandgap metal-oxide semiconductors hold promise for self-powered photoelectrochemical (PEC) type UV photodetectors (PDs) due to their inherent photoelectric properties and durability. However, inadequate charge carrier separation and transport remain a fundamental challenge for practical applications. Herein, the extraordinary efficacy of introducing gallium (Ga) into ZnO nanowire to design high-performance PEC-type PDs is demonstrated. The obtained Ga-doped ZnO (ZnO:Ga) PEC-type photodetectors exhibit superior UV photoresponse performance, featuring an exceptionally high responsivity of 233.26mA/W, an excellent detectivity of 4.18 × 1012 Jones, and a fast response/recovery time of 159/150 ms under 365nm illumination without external bias voltages. These accomplishments outperform the majority of previously reported PEC-type UV PDs. It is found that the unique properties of ZnO:Ga nanowires, including improved donor density and steeper band bending at solid-liquid interface, significantly enhance the generation, transfer, and separation of photoexcited charge carriers, thus contributing to the superior photodetector’s performance. In addition, a secure UV communication system using international Morse code is set to demonstrate the feasibility of ZnO:Ga nanowires PEC-PD as a self-powered optical receiver. This study introduces a promising approach to develop self-powered photodetectors that are highly stable, cost-effective, and poised for integration into future multifunctional optoelectronic devices.

Gate‐controlled Multispectral Response in Graphene‐Based Heterostructure Photodetector

AbstractMultispectral photodetectors are crucial for detecting light across a wide wavelength range, serving applications requiring precise wavelength specificity and spectral imaging capabilities. However, the development of these photodetectors is hindered by several challenges, including material compatibility issues, low responsivity, the complexity of signal processing, and precise bandgap engineering. A strategy is proposed using a MoS2‐graphene photodetector to address these issues. Gate‐tunable spectral responses are achieved in a graphene photodetector by utilizing carrier transfer from MoS2 and interfacial gating effects from a SiO2/p‐doped Si substrate. Precise gate bias manipulation enables selective photocurrent capture in the range of 500–680 nm, identical to the absorption of MoS2. Furthermore, by applying a highly negative gate bias, photocurrent signals below the MoS2 bandgap, i.e., in the 680–800 nm region, are detected, significantly provoking broadband photodetection. The results highlight the versatility of gate‐tunable multispectral response, leading to an exceptional responsivity of up to 1.4 × 105 mA W−1. Moreover, through the precise modulation of gate bias and incident wavelength, it seamlessly switches between negative and positive photocurrents. This study provides important insight into carrier photogeneration in sensitized graphene‐based multifunctional optoelectronic devices, establishing a versatile platform for detecting a broad range of photocurrents with a single detector.

Coexistence of Electrochromism and Bipolar Nonvolatile Memory in a Single Viologen.

Viologens are fascinating redox-active organic compounds that have been widely explored in electrochromic devices (ECDs). However, the combination of electrochromic and resistive random-access memory in a single viologen remains unexplored. We report the coexistence of bistate electrochromic and single-resistor (1R) memory functions in a novel viologen. A high-performance electrochromic function is achieved by combining viologen (BzV2+2PF6) with polythiophene (P3HT), enabling a "push-pull" electronic effect due to the efficient intermolecular charge transfer in response to an applied bias. The ECDs show high coloration efficiency (ca. 1150 ± 10 cm2 C-1), subsecond switching time, good cycle stability (>103 switching cycles), and low-bias operation (±1.5 V). The ECDs require low power for switching the color states (55 μW cm-2 for magenta and 141 μW cm-2 for blue color). The random-access memory devices (p+2-Si/BzV2+2PF6/Al) exhibit distinct low and high resistive states with an ON/OFF ratio of ∼103, bipolar and nonvolatile characteristics that manifest good performances, and "Write"-"Read"-"Erase" (WRE) functions. The charge conduction mechanism of the RRAM device is elucidated by the Poole-Frenkel model where SET and RESET states arise at a low transition voltage (VT = ±1.7 V). Device statistics and performance parameters for both electrochromic and memory devices are compared with the literature data. Our findings on electrochromism and nonvolatile memory originated in the same viologen could boost the development of multifunctional, smart, wearable, flexible, and low-cost optoelectronic devices.

Electrically modulated photoresponse and optically modulated electroresistance in a ferroelectric heterostructure with PbZr0.2Ti0.8O3 barriers

Ferroelectric heterostructures hold great promise for developing multifunctional memristors and optoelectronic devices. In this study, we report a ferroelectrically modulated photoresponse and optically modulated electroresistance behaviors in the Pt/PbZr0.2Ti0.8O3(PZT)/Nb-doped SrTiO3 (NSTO) heterostructure. The short-circuit photocurrent rises from 28 nA (after poling at +5 V) to 345 nA (after poling at −5 V) when illuminated with 360 nm of 10 mW·cm−2, exhibiting a massive photocurrent variation ratio of 1230%. This result can be attributed to the modulation of the ferroelectric polarization on the built-in field at the PZT/NSTO interface, which impacts the separation of photogenerated carriers. Furthermore, the heterostructure has a large high/low resistance ratio of 6 × 105%, which decreases to 2 × 104% when illuminated with 360 nm light. This finding is attributed to ferroelectric polarization and light illumination modulating the barrier height and width. Overall, this research suggests a promising strategy for developing self-powered heterojunction photodetectors and multifunctional memory devices.

Tailoring the anisotropic effect of Janus In2 XY (X/Y = S, Se, Te) monolayers toward realizing multifunctional optoelectronic device applications

Anisotropic effect of two-dimensional materials remains one of the most attractive properties, introducing an additional degree of freedom for tuning physical performances. In this work, we investigate the anisotropies of electronic, transport, piezoelectric, and optoelectronic properties of Janus In2 XY (X/Y = S, Se, Te) monolayers (J-In2 XY MLs) by performing first-principles calculations. We find that such J-In2 XY MLs possess moderate bandgap (2.07–2.29 eV), high carrier mobility (∼103 cm−2V−1s−1), visible light absorption (∼105 cm−1), large out-of-plane piezoelectric response and ultra-soft mechanical nature . We construct a kind of J-In2 XY-based phototransistor to investigate the optoelectronic properties under linearly polarized light. We find that the low recombination probability of photogenerated carriers ensured by anisotropic effect enhances the photocatalytic potential of J-In2 XY MLs. And the pivotal role induced by anisotropy in photocurrent can cause a prominent on/off ratio (∼100), considerable responsivity (0.038 AW−1, 0.036 AW−1) and external quantum efficiency (10.6%, 11.5%). Our study provides an avenue for the design of future anisotropic J-In2 XY-based multifunctional optoelectronic device.

All‐In‐One Optoelectronic Neuristor Based on Full‐vdW Two‐Terminal Ferroelectric p–n Heterojunction

AbstractPhotoelectric synaptic devices with optical sensing capability are of great importance in simulating human vision systems. Especially realizing all‐in‐one vision neuristor on silicon based new materials and principles is being pursued. 2D van der Waals (vdW) materials have the unique advantage of arbitrary stacking on demand. Herein, a full‐vdW two‐terminal 2D ferroelectric α‐In2Se3/SnSe p–n heterojunction is proposed to construct an optoelectronic neuristor to simulate visual synaptic functions. Implementation of these simulations is attributed to the co‐modulation of the electrical polarization reconfigurable built‐in electric field caused by p–n junction and photo‐inducing ferroelectric polarization switching. These functions include ultra‐high paired‐pulse facilitation index (457%), short synaptic plasticity, long synaptic plasticity, and retina‐like optical adaptations. The high PPF is crucial for high‐precision decoding and processing of visual information. Meanwhile, the classical Pavlovian conditioned reflexes associated with associative learning are also emulated showing the ability of the device to handle complex electrical and optical inputs. This study demonstrates that two‐terminal ferroelectric p–n heterojunctions have great potential in high‐precision multifunctional optoelectronic visual synaptic devices.

Improved Performance of Organic Light-Emitting Transistors Enabled by Polyurethane Gate Dielectric.

Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that combine in a single structure the advantages of organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). However, low charge mobility and high threshold voltage are critical hurdles to practical OLET implementation. This work reports on the improvements obtained by using polyurethane films as a dielectric layer material in place of the standard poly(methyl methacrylate) (PMMA) in OLET devices. It was found that polyurethane drastically reduces the number of traps in the device, thereby improving electrical and optoelectronic device parameters. In addition, a model was developed to rationalize an anomalous behavior at the pinch-off voltage. Our findings represent a step forward to overcome the limiting factors of OLETs that prevent their use in commercial electronics by providing a simple route for low-bias device operation.