1 Introduction

Nanomaterial (NM)-based flexible transparent electrodes (FTEs) have gained widespread popularity in portable and wearable electronics due to their exceptional attributes, including high transparency, low resistance, flexible, and formability. These versatile materials find applications in smart touch screens [1, 2], electroluminescent devices [3, 4], flexible displays [5, 6], sensors [7], and more. Several methods for fabricating FTEs from NMs have been reported, encompassing vacuum filtration [18] are slow and inevitably generates losses during the transfer process, leading to the destruction of the assembled nanomaterial film. However, the self-climbing process, proposed in our previous works [15, 19], is spontaneous and guided by the difference in surface tension between the wetted substrate surface and the assembled NM film. This transfer way exhibits favored characteristics of fast, non-destructive, and autonomous transfers, providing an optimal transfer strategy for the preparation of high-performance NM-based FTEs.

As for widely reported NM-based FTEs, graphene-based FTEs have encountered limitations due to their relatively low electrical conductivity [20]. Metal meshes, while possessing high electrical conductivity, can introduce Moiré fringes due to the interaction between overlaid repetitive structures, which can be detrimental to device performance [21]. In contrast, AgNW-based FTEs, prepared through self-assembly methods, exhibit an ordered and layered arrangement structure, resulting in low sheet resistance and high optical transmittance [22]. However, the instability of AgNWs, given their susceptibility to oxidation, cannot be ignored. To enhance their stability, various secondary conductive materials have been considered, including ionogels [5e. The output voltage remains highly stable across various frequencies. By adjusting the external resistance from 2 kΩ to 10 GΩ, we assessed the variations in power density and current density, as presented in Fig. 5f. The power density, calculated using the formula PD = IR2/A, where PD represents power density, I is the output current, R is the load resistance, and A is the effective contact area, peaks at 5 mW m−2 with an external resistance of 5 GΩ. Conversely, current density shows a decline due to Ohmic loss [47]. To evaluate durability, the AM-TENG underwent testing at a "mild" frequency of 0.5 Hz. As demonstrated in Fig. 5g, even after more than 3000 cycles, the AM-TENG consistently generated a highly stable triboelectric output current, showcasing its remarkable robustness.

Fig. 5
figure 5

Applications of the AgNWs-MXene electrodes in TENG. a Schematic illustration of the working mechanism of AgNWs-MXene-based TENG in contact-separation mode. b Current, c voltage and d charge of the TENG. e Voltage of the TENG with different contact frequency. f Variation of the current density and power density with the diverse loading resistance. g Durability measurement of the TENG, where the voltage is recorded for 3000 cycles at a frequency of 0.5 Hz. h The equivalent circuit of a self-charging system (top) and a photograph of powering the electronic watch by the charged capacitor of 22 μF (bottom). i Charging capability curves of the capacitors from 1 to 100 μF under 0.5 Hz. j Voltage real-time charge/discharge profile of a 22 μF capacitor connected in the self-charging system

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The electrical output performance of the AM-TENG proves highly effective for energy storage, particularly harnessed from human movements, which can be stored in capacitors to power various portable electronics. As illustrated in Fig. 5h and Movie S4, the AM-TENG efficiently harvests energy through hand tap** and stores it in a capacitor, facilitated by a rectifier bridge, to power devices such as electronic watches and time meters (Fig. S17a and Movie S5). When tapped by hand, the AM-TENG can effortlessly illuminate a series of 11 red LEDs (Fig. S17b and Movie S6). The charging voltage curves of the AM-TENG with different capacitors, ranging from 1.0 to 100 µF, are presented in Fig. 5i. These curves reveal that, at the same frequency, capacitors of 1.0 and 100 5µF reach 25 and 0.3 V within 300 s, respectively. To demonstrate the AM-TENG‘s effectiveness in powering electronic devices, Fig. 5j illustrates the charging and discharging processes of a watch. Initially, the voltage output from a 22 µF capacitor increases to 1.1 V in just 57 s, and subsequently returns nearly to its initial position after discharging. The capacitor is then recharged to 1.1 V as the AM-TENG is tapped again, ensuring continuous charging of the watch. Therefore, the AM-TENG developed in this study functions as a self-sustaining electronic system, capable of continuously charging various portable electronics. This innovation greatly enhances the utility and versatility of electronic devices, maximizing their potential value.

4 Conclusions

In summary, we have demonstrated an advanced approach for fabricating highly stable FTEs with an ordered and homogeneous structure, achieved through the IL-enhanced assembly of NMs. The introduction of ILs plays a pivotal role in stabilizing the NM assembly by creating a stable IL-water interface, significantly reducing NM loss. This breakthrough enables the efficient and low-loss production of a 20 cm-wide roll of AgNW-MXene composite film, capable of stably lighting a blue LED. The resulting AgNW-MXene composite film exhibits exceptional properties, including a low sheet resistance of 9.4 Ω sq−1 and impressive optical transmittance of 93%. Moreover, the film's remarkable stability is evident as it endures exposure to various environments, such as extended periods in ambient air at room temperature, high temperatures up to 200 °C, and immersion in a Na2S solution for 1 h. The combination of excellent optoelectronic properties and environmental stability makes the AgNW-MXene composite film suitable for a wide range of applications. Notably, it demonstrates a remarkable EMI SE of 30.1 dB, surpassing the industry-standard requirement of 20 dB. Additionally, the composite film serves as the foundation for assembling a TENG device. This TENG device, powered by hand tap**, can effortlessly drive electronic watches or time meters in a self-charging system. Thus, our research unveils the immense potential of the composite films developed in this study, showcasing their suitability for diverse applications in the realm of flexible optoelectronics, thanks to their exceptional properties and stability.