Introduction

Optoelectronic devices have kept pace with rapid advancements, meeting the high demands of applications such as smart windows, street lighting, laser equipment, and cameras1,2. Their popularity is due to their ease of usage, quick response times, and cost-effectiveness3,4,5. The development of nano-based materials has played a significant role in this progress. Various combinations of materials, formed into structures like nanotubes, core shells, flower-shaped, and mushrooms, have been explored to enhance performance. Previous studies on metal oxide or their composites, such as Se/TiO₂6, CuO nanowires7 and CuO/Si nanowires8 have been conducted. However, these materials exhibit limitations in sensitivity, with R values ranging from 0.1 to 0.001 mA/W.

Recently, polymers and innovative metals, including graphene, have demonstrated immense potential in advancing optoelectronic devices9,10. Among these materials, graphene and particularly thiophene derivatives are significantly notable for their excellent electrical conductivity due to their conjugated bonds. In addition to their unique properties, these materials exhibit excellent optical absorbance, which spans from the ultraviolet to the visible regions. This characteristic suggests their capability to utilize incident photons to excite electrons, functioning effectively as photocatalytic materials. Examples of polymers used for this purpose include PBBTPD: Tri-PC61BM and P3HT11,12 which have shown limited responsivity (R) values not exceeding 0.01 mA/W.

Graphene and its derivatives, like rGO, consist of single or multiple layers of carbon atoms arranged in a honeycomb lattice. This structure imparts unique properties to graphene, such as ultrafast electron mobility, exceptional photo response, outstanding thermal conductivity, and an extensive specific surface area13,14. Despite these remarkable properties, previous studies on these materials have reported a limited R value, which does not exceed 0.01 mA/W. For instance, studies on ZnO/rGO and GO/Cu2O composites have shown restricted R values15,16. Despite the extensive usage of graphene composites in previous research to develop detectors and sensors, several challenges still need to be solved. A primary concern is the limited sensitivity of these materials, indicated by their low responsivity R values. Moreover, many light sensors produced in these studies can typically detect photons only within limited regions, like UV or visible (Vis) spectra, instead of spanning a wide optical range.

This work has developed a highly ordered rGO/P2AMB S-nanocomposite as a novel and promising optoelectronic device for photon capture and sensing. The rGO/P2AMB S-nanocomposite is a type of vdW heterostructure, as reported by Y. Yu et al.17, which is formed by stacking two-dimensional rGO (2D) layers separated by intercalant compound, P2AMB, with different electronic and optical properties. The observed stacked morphology and optoelectronic performance suggest a possible vertical junction formation, likely influenced by interfacial van der Waals interactions and modulated by the polymer intercalation, which can enhance charge separation and transport efficiency. The rGO/P2AMB S-nanocomposite is analogous to a graphene-based vdW heterostructure, as rGO stands for reduced graphene oxide, a graphene derivative with oxygen-containing functional groups. Given the relative positions of the HOMO and LUMO levels of P2AMB and the Fermi level of rGO, P2AMB is expected to function as a donor component in the heterostructure, facilitating charge transfer upon illumination. The device’s topographical and morphological characteristics reveal highly ordered sheet formations. Chemical analysis determines the groups and crystalline behavior of the materials, while the bandgap and optical properties are assessed for rGO, P2AMB, and the rGO/P2AMB-nanocomposite. Electrical testing is performed on this composite via a linear sweep voltammetry technique within a potential range of -2.0 to + 2.0 V under optical illumination. The photocurrent is evaluated by examining the difference between the Jph and dark current (Jo) values. Sensitivity and efficiency are determined based on the R-value, considering the D- values. This rGO/P2AMB S-nanocomposite thin film optoelectronic device demonstrates excellent stability, sensitivity, mass production potential, and ease of fabrication, making it highly recommended for industrial applications.

Experimental section and method of Preparation of the intercalated VdW rGO heterostructure

Materials and characterization

Potassium permanganate (KMnO4, 99.8%, Pio-Chem, Egypt), 2-amino-1-mercaptobenzene (99.9%, Merck, Germany), Dimethylformamide (99.9%, Sigma Aldrich, USA), graphite powder (99.8%, Pio-Chem, Egypt), sulfuric acid (H2SO4, 99.9%, El-Nasr, Egypt), phosphoric acid (H3PO4, 99.9%, El-Nasr, Egypt), hydrochloric acid (HCl, 36%, Pio-Chem, Egypt), Hydrogen peroxide (H2O2, 50%, Pio-Chem, Egypt), ammonium persulfate ((NH4)2S2O8, 99.8%, PioChem, Egypt).

Various analytical techniques are utilized to thoroughly characterize the synthesized composite. FTIR is performed using a Bruker instrument (Germany) to identify the functional groups and confirm the chemical structure of the polymer, in the scanning range of 3500–500 cm⁻¹ with a resolution of 4 cm⁻¹. The crystallinity and phase structure were analyzed by XRD using an X’Pert diffractometer (Malvern Panalytical, Netherlands). Surface chemical composition and oxidation states were determined through XPS using a Kratos spectrometer (UK). The internal morphology and nanoscale features were examined using TEM conducted on a JEOL microscope (Japan), while surface topology was further studied via SEM using a ZEISS instrument (Germany). Finally, the optical absorption properties were investigated using a PerkinElmer UV–vis spectrophotometer (USA) in the range of 200 to 1000 nm.

The Preparation of rGO/P2AMB S-nanocomposite thin film

To prepare the rGO/P2AMB-nanocomposite, the process begins with the direct oxidation of mercapto benzene into P2AMB in the presence of rGO, using (NH4)2S2O8 as the oxidant. Initially, GO is transformed into rGO. This transformation involves mixing a suspension of graphene material (20 ml) with a reducing agent (0.06 M) monomer, specifically mercapto benzene, and stirring the mixture vigorously for 30 min. During this period, the reduction reaction occurs at room temperature.

Next, a 0.15 M solution of (NH4)2S2O8 is rapidly added to the mixture of the monomer and rGO. This addition initiates the polymerization reaction, synthesizing the rGO/P2AMB nanocomposite thin film. A glass slide is inserted into the reaction solution during the polymerization process, facilitating the formation of the thin film on its surface, in which this reaction duration is one day at room temperature. After synthesis, this thin film is subjected to treatment and drying processes to prepare it for characterization and analysis.

It is important to note that the composite material is derived from graphene oxide (GO), which is synthesized using the Hummer method. This involves mixing 0.5 g of graphite with 50 ml of H2SO4 and 7 ml of H3PO4. The mixture undergoes oxidation using 3.0 g of KMnO4. After one day, the residual KMnO4 is removed by adding 4.0 ml of H2O2. Before using this GO in the composite formation reaction, the medium is enhanced by washing the GO, which raises the pH to approximately 4.0.

The electrical testing of rGO/P2AMB S-nanocomposite thin film for light capture

The electrical testing of the synthesized rGO/P2AMB-nanocomposite thin film for light capture involves connecting the film to a CHI608E device. This connection is established by affixing two silver spots on either side of the thin film using prepared silver paste. The light capture testing is conducted by measuring the generated current density (Jph) through linear sweep voltammetry and chronoamperometry utilizing this device.

A metal halide lamp with a vacuum setup is employed for the reaction under white light, which provides full-spectrum white light. The testing measures the hot electrons generated by the film as Jph, while the dark current is measured as Jo. To determine Jph values under different photon energies, optical filters allow only specific photon energies to pass through.

The responsivity (R) is calculated using the measured values of Jph and Jo, considering the light power (P), as per Eq. (1) 18,19. Additionally, the detectivity (D) is calculated using the electron charge (e) and the area of the thin film (A), as illustrated in Eq. (2) 18,19. This setup ensures precise measurement of the film’s performance under various light conditions, providing valuable data on its potential applications in light capture technologies, Fig. 1.

$$\:\text{R}=\:\frac{{\text{J}}_{\text{p}\text{h}}\:\:-\:{\text{J}}_{\text{o}}}{\text{P}.\text{S}}$$
(1)
$$\:\text{D}=\text{R}\:\sqrt{S\:/2\:\text{e}\:\:{\text{J}}_{\text{o}}\:}$$
(2)
Fig. 1
figure 1

Illustrates the electrical configuration of the assembled vdW (rGO/P2AMB S-nanocomposite) thin-film apparatus engineered for light detection. A metal halide lamp is the illumination source, and Optical filters are employed to choose the desired light wavelength. The vdW (rGO/P2AMB) acts as the specimen under investigation in these experiments—silver paste forms electrical contacts on either side of the vdW heterostructure.

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Results and discussion

The crystalline behavior of the synthesized rGO/P2AMB S-nanocomposite is assessed by comparing it with the crystalline properties of its initial components, GO and P2AMB, as illustrated in Fig. 2(b). The prominent crystalline peaks observed in the composite indicate a significant improvement in its optical properties compared to its constituent materials. Specifically, for rGO, the characteristic peaks at 23.3° and 48.0° indicate its structure. Additionally, the P2AMB network exhibits six distinct peaks ranging from 17.2° to 35.5°. In contrast, the initially prepared GO shows a single peak at 12.1°, demonstrating its crystalline nature. The crystalline enhancements observed in the composite indicate substantial improvements in optical behavior, as the crystalline structures facilitate effective photon trapping and capture.

The crystalline size of the synthesized rGO/P2AMB S-nanocomposite is determined to be 16 nm, calculated using Scherrer’s equation (Eq. 3) 20,21,22, This calculation relies on two key parameters: the peak position (2ϴ) and the full width at half maximum (ß). The peak observed at 2θ = 23.3° was utilized to estimate the crystalline size.

$$\:{\text{D}} = 0.94\uplambda \:/{\ss}\cos\uptheta\:$$
(3)

Figure 2(a) displays the carefully performed FTIR measurements of P2AMB and the rGO/P2AMB S-nanocomposite as illustrated in Table 1. These measurements are essential for identifying the various functional groups within the P2AMB polymer, such as N-H, C-N, and C = C quinoids, located at 3366 cm⁻¹, 1310 cm⁻¹, and at 1514 cm⁻¹ and 1619 cm⁻¹, respectively. Notably, after the incorporation of rGO, significant shifts in these peaks were observed. The distinct functional group signatures of rGO, specifically C-O and C-O-C at 1069 cm⁻¹ and 1293 cm⁻¹, respectively, were also accurately identified. The shifts in band positions indicate a substantial impact of the carbon material on the polymer, reflecting changes in the chemical composition due to the composite’s formation. This variation is expected to enhance the nanocomposite’s optical properties, which can be attributed to the synergistic effect of the two materials.

Figure 2 (c) verifies and illustrates the synthesized rGO/P2AMB S-nanocomposite’s optical properties compared to the pristine P2AMB. The significant variation in optical absorbance between the polymer and the composite highlights the influence of -rGO on the optical properties, extending absorbance from the UV to the near IR region at 690 nm, compared to 600 nm for the pristine polymer. This behavior demonstrates the role of rGO in enhancing photon trapping and capture by integrating with the polymer network.

The broad absorbance observed in the nanocomposite is attributed to the Pi-Pi* electron transition facilitated by the fabricated nanocomposite. Consequently, the bandgap evaluation through the direct transition, performed using the Tauc equation (Eq. 4)23. Figure 2(d) reveals that the composite has a bandgap of 1.86 eV, compared to 2.58 eV for the pristine polymer. The reduced bandgap of the rGO/P2AMB S-nanocomposite is promising for optoelectronic applications, highlighting its potential in this field. This evaluation is based on the absorbance coefficient (α), which is estimated from the absorbance data presented in Fig. 2(c).

Conversely, the optical absorbance of pristine rGO is presented in Figure S1(a), while its corresponding bandgap is shown in Figure S1(b). The absorbance extends up to approximately 580 nm, with the estimated bandgap calculated as 2.4 eV.

$$\:{\upalpha\:}\text{h}{\upnu\:}\:=\:\text{A}(\text{h}{\upnu\:}-{E}_{g}{)}^{1/2}$$
(4)
Table 1 The summarized groups and their positions are estimated from Fig. 2(a) for FTIR analysis.
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Fig. 2
figure 2

The chemical analysis of the synthesized rGO/P2AMB S-nanocomposite compared to both rGO and P2AMB: (a) FTIR, (b) XRD, (c) optical absorbance, and (d) bandgap estimated using the Tauc equation.

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Figure 3 estimates the morphological analysis of the synthesized rGO/P2AMB S-nanocomposite, demonstrating significant interaction and connections between the rGO layers and the pristine P2AMB polymer. SEM analyses, illustrated in Figs. 3(a) and 3(b), reveal the formation of extensive sheets within the composite. These sheets reflect the rGO layers and are interspersed with spherical P2AMB nanomaterials with an average diameter of 150 nm. These polymer materials are incorporated into the sheets, highlighting the ability of these materials to form highly ordered porous structures using straightforward fabrication techniques. The TEM analyses, shown in Figs. 3(c) and 3(d) under various magnifications, further demonstrate this behavior. They reveal that the pristine P2AMB polymer is integrated within the GO material, forming a highly compact composite. Figure 3(c) distinctly shows a single sheet of rGO, while Fig. 3(d) illustrates the inserted P2AMB polymer materials, each with an average diameter of 150 nm. To emphasize the compact integration of rGO and P2AMB, the theoretical morphology is depicted in Fig. 3(e). This figure illustrates the pristine P2AMB material embedded within the rGO layers. The composite’s porous and rough surface enhances its ability to absorb light and trap photons efficiently25. In contrast, the morphology of the P2AMB material alone is shown in Fig. 3(f), where cleft spherical particles are formed. This morphology is considered a promising foundation for creating composites with other materials. The porous and cleft nature of the P2AMB polymer facilitates the insertion of additional materials, leading to the formation of highly compact composites.

Quantitative porosity assessment was carried out using the cross-sectional analysis presented in Fig. 3(e), which involved 3D surface profiling over a 500 × 600 nm region, and it is equivalent to BET analysis26. The surface displayed pronounced vertical features, with height variations reaching up to 200 nm. Due to this surface roughness, the actual 3D surface area was found to be approximately 30–50% greater than the flat, projected 2D area. This analysis suggests a highly textured morphology, indicative of mesoporous or nanostructured characteristics. The total estimated surface area reached 100 m²/g, with pore regions accounting for roughly 20 m²/g.

Fig. 3
figure 3

Morphological examination of the engineered vdW composite: rGO/P2AMB S-nanocomposite. (a-b) SEM images at different scales show well-arranged rGO layers interspersed with P2AMB droplets. (c-d) TEM imagery at varied magnifications, coupled with (e) estimated roughness and cross-sectional analysis. In contrast, (f) displays the SEM of the unmodified P2AMB.

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The electrical testing of the fabricated rGO/P2AMB S-nanocomposite optoelectronic as a promising photon capture

The promising morphology of the rGO/P2AMB S-nanocomposite, combined with its optical bandgap of 1.86 eV and crystalline size of 16 nm, underscores its potential as a susceptible optoelectronic device for photon detection. This thin nanocomposite film is electrically tested using an electrochemical workstation, CHI608E, where both sides are coated with Ag-paste to serve as connection points. The electrical tests are conducted under a vacuum tube metal halide lamp, providing a white light source. A linear sweep voltammetry study is performed using the CHI device, with a potential range of -2.0 to + 2.0 V and a scan rate of 100 mV/s. The primary goal of this testing is to estimate the generation of hot electrons on the surface of the rGO/P2AMB-nanocomposite thin film under light illumination.

Photons with their energies are trapped and captured by the composite’s morphologies, transferring their energy to the electrons. These electrons gain kinetic energy and are collected on the conducting bands of both P2AMB and rGO, creating a substantial electric field that propels the hot electrons to the external circuit. This process generates Jph, an indicator of the device’s sensitivity to photon detection. The sensitivity evaluation compares Jo to Jph values, as shown in Fig. 4(a). The values obtained are 1.5 and 2.25 mA.cm⁻², with a resulting photocurrent of 0.75 mA.cm⁻², reflecting the excellent photocatalytic and sensitizing properties of the rGO/P2AMB-nanocomposite for photon capture. The dark current measurement confirms the semiconductor nature of this optoelectronic device. The insertion of P2AMB enhances the stability of the fabricated rGO/P2AMB-nanocomposite within the rGO structure, ensuring better structural integrity and forming a more robust composite material. The coverage of this graphitic material with P2AMB means that the polymer effectively coats the surfaces of the rGO layers. This coating improves the composite’s overall stability and durability. Furthermore, the pristine polymer’s anti-corrosion properties are crucial in maintaining the device’s long-term stability and functionality. This means that the P2AMB polymer helps prevent the composite material’s degradation over time, thus extending its operational lifespan. In addition to these benefits, conducting electrical measurements in a standard air environment without chemical solutions contributes significantly to the device’s longevity. This testing method is less invasive and reduces the risk of chemical damage to the composite, ensuring that the rGO/P2AMB-nanocomposite can perform effectively over an extended period. These combined factors underscore the enhanced stability, durability, and efficiency of the rGO/P2AMB-nanocomposite, making it a promising candidate for various optoelectronic applications. The stability provided by the P2AMB polymer, coupled with the robust structure of the reduced graphene oxide, results in a highly effective material for photon capture and light detection as illustrated in Fig. 4(b).

On the other hand, the electrical properties of pristine rGO have been evaluated and are presented in Figure S2. The study estimates the Jph and the dark current density (Jo), which are found to be 0.52 mA.cm⁻² and 0.28 mA.cm⁻², respectively, at an applied potential of 2 V. These values indicate a moderate optoelectronic response, with the difference between Jph and Jo demonstrating the material’s ability to generate a photocurrent under illumination. This behavior highlights the fundamental electronic characteristics of rGO, serving as a reference for its performance when integrated into composite materials.

Fig. 4
figure 4

Illustrates the electrical evaluation of the vdW (rGO/P2AMB-nanocomposite) thin film for optoelectronic photon detection, displaying (a) the photogenerated current Jph, which exhibits Ohmic behavior like that observed in dark conditions and (b) a panel confirming consistent performance across multiple illumination tests.

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The sensitivity of the nanocomposite thin film optoelectronic devices is related to their ability to discern various photon energies and produce a corresponding Jph. This characteristic is illustrated in Figs. 5(a) and 5(b). Specifically, the Jph values range from 2.2 to 1.95 mA/cm², corresponding to photon energies between 3.6 and 1.7 eV. These Jph values effectively demonstrate the sensitivity of the rGO/P2AMB-nanocomposite thin film optoelectronic device for light detection and capture. Figure 5(b) highlights this behavior by summarizing the Jph values obtained at 2.0 V, showing an apparent increase in Jph with increasing photon energy.

The performance of this optoelectronic device is attributed to the superior photocatalytic materials used in its construction. These materials exhibit a strong response to photons based on their energy. As the photon energies increase from 2.3 to 3.6 eV, the ability to activate electrons from the valence band to the conduction band increases, generating hot electrons. These electrons, collected on the conduction bands, contribute to the current. Notably, these photon energies exceed the composite’s bandgap of 1.86 eV. The excess energy appears as kinetic energy for the generated electrons, leading to the generation of an electric field around the rGO/P2AMB-nanocomposite materials, producing a Jph value related to the movement of these hot electrons in the external circuit.

However, photons with an energy of 1.7 eV possess lower energy than the bandgap. Consequently, these photons cannot effectively excite electrons, and the resulting Jph values are primarily due to bond vibration rather than electron excitation. This nuanced behavior underscores the material’s capacity to respond selectively to different photon energies, thereby enhancing the device’s overall sensitivity and efficiency in light-sensing applications.

Fig. 5
figure 5

Presents (a) the electrical linear sweep voltammetry results, spanning from − 2.0 to 2.0 V of the fabricated vdW (rGO/P2AMB-nanocomposite thin film) optoelectronic device with photon energies varying between 2.3 and 3.6 eV, and (b) the calculated Jph at a potential of -2.0 V.

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About the formation of a new type of Van der walls materials from ordered sheets of rGO and polymers

Research into new vdW materials, including combinations of rGO and polymers, is intriguing due to their potential unique optoelectronic and mechanical properties. However, integrating rGO with polymers to form vdW structures still needs to be explored. Initial studies on applying vdW forces in rGO centered on measuring vacuum pressures, emphasizing their importance in rGO films27,28. A sensor composed of an rGO film on polydimethylsiloxane )PDMS( substrate, which refers to a surface or material made of PDMS, a silicon-based organic polymer found to be responsive to changes in vacuum pressure, with the rGO layers compressing under increased pressure, leading to reduced electrical resistance. PDMS is widely used in scientific and engineering applications due to its flexible, biocompatible, and transparent properties. It is frequently employed as a substrate in microfluidic devices, soft lithography, cell culture, and biological research because it is easy to mold, chemically stable, and gas permeable. The sensor made on such a substrate could effectively measure pressures ranging from 0.2 to 102 kPa. The research highlights two primary types of vdW interactions within the rGO layers that correlate to resistance variations – attributing negative resistance shifts to interlayer interactions and positive shifts at lower pressures to intralayer interactions, including the effect of intercalants. Employing vdW forces for stacking 2D materials is a recognized approach for enhancing their physical characteristics and functionality, underscoring the critical role of vdW forces in material engineering, as detailed in 29,30,31. This review covers advancements and hurdles in constructing heterostructures from materials such as graphene and Transition Metal Dichalcogenides (TMDs) and recognizes potential applications in diverse technology sectors. Additionally, studies on Nb2Se9 demonstrate the way that vdW forces can facilitate the origination of high-quality 2D materials, noting the successful development of Nb2Se9 flakes with impressive electrical and optical attributes through the vdW-driven separation of atomic layers in bulk crystals.

In specific scenarios, orderly arranged rGO sheets can form what is known as vdW superlattices. Employing strategies like Layer-by-Layer Assembly and controlled stacking of rGO sheets can produce a vdW superlattice with characteristics distinct from individual rGO sheets. These superlattices’ properties are influenced by the interactions between layers, which can be fine-tuned by varying layer twist angles, adding intercalants, and achieving proper rGO sheet alignment. It’s plausible to predict that combining these superlattices with other 2D materials could modify vdW properties. For example, teaming up rGO with different 2D materials like hexagonal boron nitride may result in a hybrid structure with novel functionalities. Quantum confinement and interlayer coupling in vdW superlattices can lead to effects like superconductivity; rGO superlattices paired with suitable functional 2D materials might similarly display these traits. The deliberate stacking of rGO sheets is fundamental to exploring their relationship with vdW superlattices and unlocking new possibilities for application due to significant interlayer interactions and the combined properties of the overall superlattice.

Benefits of VdW heterostructures from rGO

Heterostructures incorporating rGO can offer various advantages due to the synergy between rGO’s distinct properties and those of vdW heterostructures. These benefits include (1) Tunable Electronic Band Structure, where the arranging and stacking rGO layers can modify their electronic band structure, permitting customization of electronic properties. (2) Enhanced Conductivity: Reducing graphene oxide to rGO increases electron density and, therefore, restores much of graphene’s conductivity, and an organized stack in vdW structures may enhance charge movement. (3) Improved Mechanical Properties: Organized layers of rGO within vdW superlattices increase mechanical robustness, flexibility, and durability, suitable for applications in flexible electronics and composite materials. Moreover, rGO can have its defects engineered through functional groups to improve mechanical resilience. (4) High Thermal Conductivity: rGO possesses significant thermal conductivity, exploited in vdW architectures to achieve effective heat management in devices such as electronic thermal spreaders. (5) Advantaged Optical Properties: Carefully arranged rGO affects light interaction, which is advantageous for uses in photodetectors, LEDs, and solar panels. (6) Conductive Transparency: Crystals made from rGO-based vdW structures provide transparency and electrical conductance, which is desirable for transparent electrodes in various display technologies. (7) Energy Storage Applications: With a vast surface area and conductivity, rGO in vdW configurations is superior for energy storage systems like advanced batteries and capacitors, offering enhanced power efficiency and longer service life. Furthermore, it’s essential to highlight the array of Ecological Uses, some but not limited to 1)Enhanced Adsorption: The broad surface area and functional configuration of such heterostructures make them optimal for environmental clean-up operations like water treatment and air purification. 2) Catalysis Benefits: Their considerable surface space and customizable electronic properties make rGO vdW superlattices potent catalysts in chemical processes relevant to energy cells and hydrogen manufacture. 3) Sensing Applications: The extensive surface area and adjustable electronic properties of rGO vdW stacks enhance their precision in detecting sensitive substances, making them ideal for use in sensors and diagnostic tools.

The intercalation of VdW rGO superlattices by P2AMB

Insights into the intercalation processes of vdW superlattices are emerging, highlighting the use of a variety of materials from TMDCs32 to atomic 2D crystals like MoS2 and WS233, including 2 H-TaS2. Inserting guest species into these host structures has led to notable effects, such as superconductivity induction, modification of lateral transport, and distinctive tunneling phenomena34. Established methods for intercalation include chemical slicing with molten salt [24], electrochemical techniques, and in situ methods. These intercalation strategies have improved dielectric properties, electron transportation, and the formation of polarized centers. Moreover, new phases that exhibit emergent properties may develop, enhancing superconductivity. The hypothesis is that the intercalation of rGO vdW superlattices with P2AMB could lead to various material enhancements and modifications. The anticipated benefits of this process involve: (1) Strengthened mechanical traits: P2AMB promises increased robustness and flexibility for the superlattice, even stress distribution, and augmented resilience. Enhanced conductivity: P2AMB integration with rGO layers boosts charge transfer and electrical efficiency. Upgraded thermal properties: P2AMB improves heat resistance and thermal conductance. Increased surface area: P2AMB enhances rGO layer gaps, increasing surface area and porosity. (2) Augmented chemical functionality: Incorporating P2AMB may add more functional sites and catalyst points, thus elevating the superlattice’s reactivity and catalytic capacity. (3) Improved optoelectronic features: P2AMB’s adjustments to the superlattice may alter its optical absorption and emission, leading to superior photocatalytic and optoelectronic performance. (4) Superior environmental tolerance: P2AMB provides a barrier against moisture and oxidation, improving structural stability and longevity. The integration of P2AMB into the rGO vdW superlattices creates a composite that is more resistant to environmental factors such as moisture and oxidation. P2AMB acts as a protective layer, preventing water molecules and oxygen from penetrating the rGO layers. This enhances the structural stability of the superlattice, ensuring that it remains intact and functional over more extended periods and under various environmental conditions. Consequently, devices utilizing this composite material can operate with excellent reliability and durability in diverse settings, making them suitable for long-term environmental stability applications. (5) Tailored electronic band structure: With P2AMB, customizing the superlattice’s band structure becomes feasible, which includes tuning the band gap and optimizing carrier mobility for specific electronics applications. Thus, integrating P2AMB with rGO vdW superlattices stands to substantially enhance their mechanical, electrical, thermal, and chemical attributes, which paves the way for broader use in sectors such as sensing, catalysis, optoelectronics, environment protection, and energy conservation. We detail the method for fabricating an rGO vdW superlattice intercalated with P2AMB, highlighting the exceptional qualities of such a device.

The efficiency of the optoelectronic device

The efficiency of the fabricated rGO/P2AMB S-nanocomposite thin film optoelectronic device hinges on its ability to convert photons into hot electrons, generate an electric field around its components, and subsequently produce Jph values. To assess this efficiency, the responsivity (R) and detectivity (D) values are calculated as shown in Eqs. 1 and 2 and illustrated in Figs. 6(a) and (b), respectively. The R-value reaches an optimal level of 22.0 mA/W at 3.6 eV and decreases to 1.95 mA/W at 1.7 eV as the photon energy or frequency decreases. Similarly, the D value peaks at 0.51 × 10¹⁰ Jones and decreases to 0.45 × 10¹⁰ Jones.

These results indicate the fabricated optoelectronic device’s high sensitivity, showcasing its superior performance compared to other materials reported in the literature (see Table 2), such as Co₂O₃/polypyrrole [39], MnO₂/polypyrrole [40], and polyaniline-TiO₂ composites35. The impressive R and D values reflect the device’s exceptional capability for light detection and efficiency in converting photon energy into electrical signals, thereby underscoring its advanced optoelectronic properties.

Table 2 The extraordinary sensitivity dynamics of the innovatively fabricated VdW (rGO/P2AMB S-nanocomposite) thin film optoelectronic device compared to prior studies showcasing its unparalleled superiority and advanced championship qualities relative to data given in the literature.
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Fig. 6
figure 6

provides detailed characteristics of the fabricated vdW (rGO/P2AMB S-nanocomposite) thin film optoelectronic device under different photon energies. Specifically, panel (a) illustrates the photo-responsivity, R, while panel (b) demonstrates the detectivity, D. The photon energies assessed range from 3.6 eV to 1.6 eV.

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The mechanism for the VdW structure of rGO/P2AMB nanocomposite

The vdW structure of the rGO/P2AMB nanocomposite is meticulously estimated through the proposed model, alongside the generated photocurrent electrons, as illustrated in schematic Fig. 7. This figure outlines the essential parameters that characterize the vdW properties of this nanocomposite material. The distinctive structure and its superior optoelectronic performance can be attributed to several interconnected features, as described below.

The rGO/P2AMB nanocomposite forms a layered vdW heterostructure, where the rGO sheets act as the primary framework. These graphene-like layers (depicted in gray) are intercalated with P2AMB polymer molecules. The intercalation process enhances the structural stability of the composite, providing a robust matrix that facilitates better electronic interaction between the layers. This layered architecture not only strengthens the physical structure but also creates an ideal platform for efficient charge transport.

Upon exposure to incident light, the rGO/P2AMB nanocomposite exhibits remarkable photon absorption properties. The absorbed photons transfer their energy to electrons within the composite matrix, leading to the generation of high-energy electrons, commonly referred to as hot electrons. These hot electrons are propelled toward the conduction band, significantly enhancing the photocurrent density and reinforcing the material’s effectiveness in light detection and energy conversion.

The vdW forces between the rGO sheets and P2AMB molecules play a critical role in facilitating charge transport. These non-covalent interactions promote efficient charge separation, preventing recombination and enabling the smooth transfer of electrons through the composite. The strong electronic coupling between the rGO and P2AMB layers ensures a superior optoelectronic response, setting the material apart from conventional light-sensitive composites.

Based on our optical and electrochemical measurements for the rGO/P2AMB nanocomposite, the HOMO level of P2AMB is estimated to be approximately − 5.34 eV, and the LUMO level is around − 3.48 eV, yielding an optical bandgap of 1.86 eV, consistent with the UV-Vis absorption data. The Fermi level of rGO is approximately − 4.6 eV, based on literature values for lightly reduced graphene oxide. This energy alignment supports the following mechanism: Upon photoexcitation, electrons in P2AMB are excited from the HOMO to the LUMO. Since the LUMO of P2AMB (–3.48 eV) lies above the Fermi level of rGO (–4.6 eV), electrons can efficiently transfer from P2AMB to rGO, where they contribute to the photocurrent. Concurrently, holes remain in the HOMO of P2AMB (–5.34 eV), enabling effective spatial charge separation and minimizing recombination.

The photogenerated electrons induce a significant electric field within the composite, contributing to the observed Jph. This effect enhances the device’s photoresponsivity (R), a key parameter that measures the material’s sensitivity to light. The consistent performance observed during repeated illumination tests confirms the high sensitivity and reliability of the nanocomposite for photon detection applications.

A crucial advantage of the rGO/P2AMB nanocomposite is its enhanced stability and structural integrity. The P2AMB polymer coating not only strengthens the composite structure but also acts as a protective barrier against environmental degradation. The anti-corrosion properties of P2AMB ensure long-term durability, making the nanocomposite highly suitable for real-world optoelectronic applications. Furthermore, the ability to perform electrical measurements in standard air environments without chemical solutions further extends the device’s operational lifespan.

In summary, the vdW heterostructure of the rGO/P2AMB nanocomposite represents a groundbreaking advancement in light-detecting and energy-harvesting technologies. Its superior optoelectronic properties, combined with exceptional stability and sensitivity, make it a highly promising candidate for next-generation optoelectronic devices. This behavior was evaluated based on the device’s response time, which was determined to be approximately ~ 5 s and recovery time of ~ 2 s, as shown in Figure S3. This response time reflects the material’s sensitivity to incident light and highlights the effective photoactive interaction between the graphene-based structure and the polymer matrix. Such a rapid and stable response indicates the material’s potential for optoelectronic applications, showcasing its promising performance.

Fig. 7
figure 7

Schematic illustration of the vdW heterostructure of the rGO/P2AMB nanocomposite. The layered architecture consists of reduced graphene oxide (gray spheres) intercalated with P2AMB molecules (orange spheres), forming a stable and efficient optoelectronic material, (this schematic is designed using the open-access tools: Avogadro (Version 1.95) for molecular modeling and export of 3D atomic structures (https://avogadro.cc))

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Conclusions

An innovative rGO/P2AMB S-nanocomposite has been developed, integrating a vdW rGO superlattice with P2AMB, showing promise as an advanced optoelectronic material suitable for photon detection and sensing applications. Spectral analysis reveals the composite’s broad absorption capabilities into the near-infrared range and presents an optimal bandgap of 1.86 eV. X-ray diffraction (XRD) identifies crystalline formations with 16 nm particle peaks, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrate spherical nanoparticles organized in structured layers. The optoelectronic properties of the nanocomposite thin film, notably photon absorption and detection capacity, were found to have a photocurrent of 0.75 mA/cm². The Jph values increased from 1.95 to 2.2 mA/cm² with higher photon energies while examining several photon energies between 1.7 and 3.6 eV. Maximum device responsivity reached about 22.0 mA/W at the highest photon energy examined, reducing to 1.95 mA/W at lower energies. The peak detectivity (D) value also registered at 0.51 × 10¹⁰ Jones before dropping to 0.45 × 10¹⁰ Jones at decreased photon energies. This crafted vdW heterostructure demonstrates remarkable optical properties and heightened sensitivity, highlighting the potential advantages of incorporating rGO superlattices with P2AMB interlayers. Its possibility for cost-effective mass production further affirms its suitability for light detection applications. In summary, the rGO/P2AMB S-nanocomposite is highly effective in its optical performance and sensitivity, offering advantageous features such as low cost and scalability. These characteristics make it a strong contender for efficient light capture applications. Future research directions include exploring its applicability in photovoltaic systems, photocatalytic processes, and medical technology.