Ultra-High-Efficiency Solar Capture Device Based on InAs Top Microstructure

Abstract

Research on how to efficiently utilize solar energy can effectively address the current situation where excessive carbon emissions threaten the natural environment. The solar capture device, as the core component of the solar thermal photovoltaic system, can significantly enhance the absorption properties of the solar thermal photovoltaic system, which is of high research value in the solar energy application area. In this paper, a metamaterial broadband solar capture device based on the top microstructure of semiconductor InAs material is proposed. The model is fabricated from top to bottom with the semiconductor InAs material at the top with Ti material to make hollow cylindrical microstructures, and a combination of SiO₂ material film, Ti material film, and Cu material film as the substrate. In addition to incorporating the properties of metamaterials, the model is also inspired by the quantum-limited domain effect of nano-semiconductors by using the incorporation of InAs top microstructures at the top to further improve the model’s absorption properties. The model was calculated to have an average absorption in the 280–2500 nm waveband of 96.15% and a weighted average absorption in the 280–4000 nm waveband of 97.71% at AM1.5. Results of calculating the model’s reflectivity in the 280–20,000 nm bands show that the reflectivity of the model is higher than 80% in all the bands after the wavelength of 7940 nm, so the model has a certain spectral selectivity. In addition, the thermal radiation efficiency of the model in the 280–2500 nm waveband, when it is used as a thermal emitter, is calculated to reach 94.40% in this paper. Meanwhile, the capture device has good angular insensitivity, which has high potential for practical applications.

1. Introduction

Social development cannot be separated from scientific and technological progress, and energy is the material support for scientific and technological development [1]. Currently, fossil fuels are still the main source of energy supply [2]. However, fossil fuels produce large amounts of carbon emissions while supplying energy, and excessive carbon emissions seriously threaten the natural environment [3]. Determining how to reduce carbon emissions is a worldwide issue nowadays, which is of great importance to the long-term development of all mankind. As a clean energy source, solar energy does not cause waste residue, wastewater, or waste gas in the process of utilization [4,5]. Research on how to effectively utilize solar energy is an effective route to cutting carbon emissions [6].

Today, the two main ways of utilizing solar energy are photovoltaic conversion and photothermal conversion [7]. Photovoltaic conversion is mainly based on the photovoltaic effect [8], such as solar cells [9,10]. Solar photovoltaic (PV) utilization is among the simplest ways to use solar energy, but the conversion efficiency of current PV conversion systems is generally low, and the material requirements are high [11]. Solar photothermal conversion has a high utilization rate of light energy and relatively low material requirements, and can be used in a wide range of applications, such as thermal photovoltaics, cogeneration, and catalyzed hydrolysis [12]. High-efficiency broadband solar capture devices are the heart of solar thermal PV systems [13], and are important for improving the absorption efficiency of solar thermal PV systems [14]. The spectrum of solar energy radiation includes ultraviolet, visible, and infrared bands (280–4000 nm) [15], and research on broadband solar capture devices that can cover this band is essential for the exploitation and use of solar energy [16,17]. It is difficult for conventional natural materials to realize high absorption efficiencies over a wide bandwidth [18]. With the rapid development of nanotechnology, increasingly artificially fabricated nanoscale capture devices have been proposed; e.g., in 2008, Landy et al. first presented a metamaterial narrowband capture device having single-frequency absorption peaks [19]. In 2017, Ye et al. presented a broadband terahertz capture device based on graphene flakes [20]. In 2021, Dong et al. presented a novel terahertz (THz) metamaterial (MM) modulator with dual functional properties based on vanadium dioxide (VO₂) [21]. The electromagnetic bands of sunlight can interact well with certain nanoscale capture devices, so the use of nanotechnology can make solar capture devices with strong absorption properties that are not found in traditional materials [22,23]. Thomas et al. presented a semiconductor multilayer selective solar absorber for non-concentrated solar thermal energy conversion [24]. Tervo et al. proposed a semiconductor dielectric metal solar absorber with high spectral selectivity [25]. Cao et al. reported that silicon nanowires (Si NWs) can significantly enhance the absorption of sunlight [26]. Good nanoscale solar Vobroadband capture devices enable ultra-broadband efficient absorption in solar radiation wavebands, thus greatly improving the efficiency of solar energy usage [27,28]. Due to the polarization characteristics of sunlight through the atmosphere and non-vertical incidence, broadband solar capture devices must have polarization-insensitive and wide-angle absorption capabilities to have a good practical application value, which also need to be the focus for a broadband solar capture device during the design stage [29].

At the nanoscale, the fluctuations of particles in matter are affected by size and can exhibit properties that are quite different from those in the macroscopic size state [30]. The quantum-limited domain effect is the special effect that occurs in semiconductor materials at the nanoscale [31,32,33]. The quantum domain-limiting effect is such that when the diameter of a semiconductor nanoparticle is shorter than the Bohr diameter of the exciton, the mean free range of the electron is limited by the small particle size and is confined to a very small range, and the hole can easily form an exciton with it, causing an overlap of the electron and hole wavefunctions, which can easily give rise to an exciton absorption band. In the meantime, the vibronic intensity of the exciton also increases with decreasing particle size, and there is an exciton-enhanced absorption and blue-shift [34]. Semiconductor materials themselves have a certain absorption capacity for electromagnetic waves, which is related to their forbidden bandwidth [35,36,37]. In addition, semiconductor materials at the nanoscale appear to have enhanced exciton oscillator strength due to quantum-limited domain effects, which result in a resonant absorption wavelength blue-shift when the exciton interacts with an electromagnetic wave [38].

Currently, metamaterial-based solar energy capture devices mainly realize broadband absorption through metal–insulator–metal (MIM) multilayer structures. This structure favors the plasmon excitation. However, few studies have discussed the top microstructure. We add semiconductor microstructures to the conventional MIM structure and utilize the quantum-limited domain effect of nano-semiconductors for further enhancement of the model absorption. There are not many studies in this area and there is a large research gap. What is more valuable is that such an attempt does not just provide new ideas for solar energy capture devices. Since the absorption waveband of semiconductors can be roughly calculated by the forbidden bandwidth, almost all metamaterial energy capture devices can realize the enhancement of absorption performance by adding semiconductor microstructures with relevant forbidden bandwidths on the top. This is the main innovation of this paper.

In this paper, we present a metamaterial broadband solar capture device based on the top microstructure of semiconductor InAs material. The model is fabricated from top to bottom with the semiconductor InAs material at the top with Ti material to make hollow cylindrical microstructures, and a combination of SiO₂ material film, Ti material film, and Cu material film as the substrate. Based on the data calculations, the average of the model’s absorption in the 280–2500 nm waveband was 96.15%, and the weighted average absorption in the band of 280–4000 nm was 97.71% at AM1.5. Findings from calculating the reflectivity in the 280–20,000 nm band show that the model exhibits low reflectivity at solar radiation wavebands and high reflectivity at thermal infrared wavebands, and all the reflectivity in the band after the wavelength of 7940 nm is higher than 80%, with a certain degree of spectral selectivity, which gives the model a better resistance to thermal radiation. Moreover, the thermal radiation efficiency of the model when used as a thermal emitter was 94.40% in the 280–2500 nm waveband. Meanwhile, the results of scanning simulations of sunlight with different polarization and incidence angles show that this model exhibits excellent polarization insensitivity and wide-angle absorption properties.

2. Structural Design and Parameterization

In this paper, a capture device model based on the microstructure of the top of the semiconductor is proposed, and the structure is shown in Figure 1a. The model is fabricated from top to bottom with the semiconductor InAs material at the top with Ti material to make hollow cylindrical microstructures, and a combination of SiO₂ material film, Ti material film, and Cu material film as the substrate. The XOY graphs of periodic structural units are shown in Figure 1b, where the period length (P) of this model is 400 nm, and the hollow cylindrical microstructure has an inner radius (r) of 96 nm and an outer radius (R) of 130 nm. In Figure 1c, the thickness (H1) of the hollow cylinders of InAs material at the top of the periodic structural unit is 40 nm, the thickness (H2) of the hollow cylinders of Ti in the second layer is 1000 nm, the thickness (H3) of the film of SiO₂ material in the third layer is 50 nm, the thickness (H4) of the film of Ti in the fourth layer is 200 nm, and the fifth layer, which is also the lowest layer of the model, is one layer of Cu film with a thickness (H5) of 200 nm, and is mainly used to reduce the light wave passage rate. The dielectric constants of the materials modeled are taken from the Palik manual [39]. In the simulation of the model using FDTD Solutions software (Lumerical 2020 R2.4), the lighting source is set to be a planar light source, the periodic boundary conditions are selected for the X and Y dimensions, and the PML condition is selected for the Z dimension [40,41,42].

3. Calculation Results and Discussion

3.1. Analysis of Absorption Properties

After simulating the model using FDTD Solutions software, plots of the model’s absorption properties data were derived. Figure 2a displays the schematic graph of the absorption, reflectivity, and transmittivity in the 280–4000 nm waveband (whole wave band of solar radiation), from which it can be known that the model’s absorption in the 280–2340 nm waveband is all over 90%, with a high absorption bandwidth up to 2060 nm. According to the solar radiation spectrum, solar radiation energy is mostly concentrated in the 280–2500 nm range, which makes up 99% of the total energy, so although this model does not have a high absorption rate after 2500 nm, it has a very minor effect on the absorption of sunlight. According to the data calculations, the model’s average absorption is 96.15% in the 280–2500 nm band. Additionally, the model’s reflectivity in the 280–20,000 nm waveband is calculated in this paper, and the results are displayed in Figure 2b. As can be easily visualized from the graph, the model exhibits low reflectivity at solar radiation wavebands and high reflectivity at thermal infrared wavebands, and a reflectivity greater than 80% in the bands after the wavelength of 7940 nm. The model has a certain degree of spectral selectivity, which gives the model a better resistance to thermal radiation. In contrast to conventional broadband solar capture devices, the spectrally selective capture device is more stable at high working temperatures [43]. In terms of Kirchhoff’s law of thermal radiation, the higher the reflectivity of this model to the thermal infrared band, the weaker the ability to radiate thermal infrared waves, which also greatly reduces the heat loss of the model; this is vital for increasing the efficiency of solar photothermal conversion [44,45].

3.2. Absorbed and Radiant Energy Analysis

In this paper, the absorption of the solar energy spectrum by this model under AM1.5 conditions, as well as the energy radiated by the capture device in the 280–2500 nm waveband, are also simulated to investigate the properties of this model as a solar capture device and thermal emitter, respectively. The total spectral formula for AM1.5 solar incident energy is [46]:

$${\eta }_A={\displaystyle \frac{{\int }_{{\lambda }_{Min}}^{{\lambda }_{Max}}A\left(\omega \right)I_{AM1.5}\left(\omega \right)d\omega }{{\int }_{{\lambda }_{Min}}^{{\lambda }_{Max}}{I}_{AM1.5}\left(\omega \right)d\omega }}$$

(1)

Figure 3a shows the radiation spectrum at AM1.5 illumination. The black part of this graph represents the standard energy spectrum under AM1.5 illumination, the red part represents the energy absorbed by the model, and the green part represents the energy loss. After calculation, the weighted average absorption in the 280 nm to 4000 nm waveband under the AM1.5 condition is 97.71%, and the solar energy loss is just 2.29%, which makes the broadband absorption properties of the model very impressive.

The equation for the thermal emission efficiency (η_E) is [47]:

$${\eta }_E={\displaystyle \frac{{\int }_{{\lambda }_{min}}^{{\lambda }_{max}}\epsilon \left(\omega \right)·I_{BE}\left(\omega ,T\right)d\omega }{{\int }_{{\lambda }_{min}}^{{\lambda }_{max}}{I}_{BE}\left(\omega ,T\right)d\omega }}$$

(2)

where I_BE (ω, T) denotes the intensity of ideal blackbody radiation at frequency ω and temperature T.

Figure 3b displays the thermal radiation profile at a high temperature of 1000 K. The black curve is the ideal blackbody radiation profile, and the red region is the modeled thermal radiation. In the 280–2000 nm waveband, the model’s actual thermal radiation is in almost perfect agreement with the ideal blackbody radiation, showing a more pronounced loss of thermal radiation only in the band after 2000 nm. By calculation, the thermal radiation efficiency reaches 94.40% in the entire waveband range of 280–2500 nm, which proves that the model can also be used as a thermal emitter with very good thermal radiation performance, and the application value of the model is further enhanced.

3.3. Physical Mechanism Analysis

To investigate the physical regime underlying the model, a total of six peak wavelengths (295 nm, 400 nm, 680 nm, 1030 nm, 1860 nm, and 2800 nm) corresponding to the electric field maps of the model’s XOZ surface in the range of ultraviolet (UV), visible (VIS), and infrared (IR) wavelengths covered by solar radiation are selected for analysis in this paper. The absorption of a light wave by a semiconductor is related to its forbidden bandwidth and can be calculated by the following equation:

$${\lambda }_{Max}={\displaystyle \frac{hc}{E_g}}$$

(3)

where ${\lambda }_{Max}$ denotes the maximum optical wavelength at which the semiconductor material can absorb light waves. According to the forbidden band, the width of the InAs semiconductor is 0.36 eV, and it can be calculated that the ${\lambda }_{Max}$ of the InAs semiconductor material that can absorb the light waveband is 3444.4 nm, which is highly overlapped with the solar radiation waveband. However, since the absorption of the thermal infrared waveband reduces the thermal stability of the model, we would like to enhance the absorption in the 280–2500 nm waveband of the model without enhancing the absorption in the long wavelength waveband. According to the conditions under which the quantum-limited domain effect arises, the thickness of the InAs hollow cylinders used in the model is 40 nm, which is smaller than the exciton Bohr diameter of the InAs semiconductor (62–74 nm), and the quantum-limited domain effect occurs in the nano-semiconductor material. The model absorption properties are enhanced due to the emergence of exciton absorption bands from the quantum confinement effect. At the same time, the absorption band will be blue-shifted, and it can be seen from Figure 4 that the absorption contribution of the top microstructure of the model is very small at an optical wavelength of 2800 nm, which also indicates that the ${\lambda }_{Max}$ of the top InAs microstructure is reduced.

It is indicated in Figure 4a that when the incident light wavelength is 295 nm, the electric field is mainly concentrated on the inner sides of the InAs hollow cylindrical microstructures and the upper part of the outer sides with the Ti hollow cylindrical microstructures. Due to the occurrence of the quantum-limited domain effect, the excitons on the inner side of the InAs hollow cylindrical microstructures couple with the light wave to appear as exciton absorption bands, realizing the locally enhanced absorption of the light field. The electric field distribution in the upper part of the outer face of the Ti hollow cylindrical microstructures occurs because of the generation of localized surface plasmon resonance (LSPR) on the metal surface realizing the strong absorption of light waves [48,49,50]. It can be observed from Figure 4b that at the wavelength of the incident light of 400 nm, the absorption of light waves by the model mainly utilizes the coupling effect of excitons on the inner surface of the InAs hollow cylinders with the light waves, as well as the LSPR in the upper part of the outer face of the Ti hollow cylindrical microstructure [51,52]. In Figure 4c, the incident light is at a wavelength of 680 nm, and the absorption by the model primarily utilizes the coupling effect between the excitons on the outer surface of the InAs hollow cylindrical surface and the light wave, as well as the LSPR on the upper part of the outer surface of the Ti hollow cylindrical microstructures. In addition, surface plasmon resonance (SPR) between metal–dielectric surfaces also appears at the contact surface of Ti hollow cylindrical microstructures with SiO₂ membranes [53,54]. In Figure 4d, the incident light is at a wavelength of 1030 nm, and the absorption of the light wave by the model mainly takes advantage of the coupling effect between the excitons on the inside and outside surfaces of the InAs hollow cylinder and the light wave, the LSPR on the upper part of the outer face of the Ti hollow cylindrical microstructure, and the SPR occurring at the contact surface of the Ti hollow cylindrical microstructure and the SiO₂ membrane [55]. In Figure 4e, the incident light is at a wavelength of 1860 nm. Due to the long light wavelength, a strong LSPR phenomenon also occurs in the lower part of the model Ti hollow cylindrical microstructure, in addition to the upper part of the outer side of the model Ti hollow cylindrical microstructure. Strong SPR also occurs at the contact surface between the Ti hollow cylindrical microstructure and the SiO₂ film [56]. In Figure 4f, the incident light is at a wavelength of 2800 nm. The LSPR on the outer side of the model Ti hollow cylindrical microstructure occurs in the lower part as the wavelength is further increased. Together with the SPR occurring at the contact surface between the Ti hollow cylindrical microstructure and the SiO₂ membrane, it realizes the powerful absorption of the light wave. In summary, the coupled effect of excitons generated by nano-semiconductor materials and light waves, as well as the combined effect of LSPR and SPR between metamaterials and light waves, achieve efficient broadband absorption of light waves.

3.4. Comparison of Five Different Structures

A suitable structure is critical for this capture device to realize efficient broadband absorption, and in this section, the absorption performance of five different structural models is discussed and compared to argue that the model presented in this paper has certain structural superiority. In Figure 5a, the five structures are represented as Case 1. A model with a combination of a SiO₂ material layer, Ti material layer, and Cu material layer in order from top to bottom (no microstructure model) is Case 2. A hollow cylinder microstructure of Ti material was added to the base structure of Case 1 (Ti hollow cylinder microstructure model); this is Case 3. A layer of a hollow cylindrical microstructure of an InAs semiconductor material is added on the top on the basis of Case 2 (the model presented in this paper); this is Case 4. A solid cylindrical microstructure of InAs material combined with Ti material from top to bottom is added on the base structure of Case 1 (solid cylindrical microstructure model); this is Case 5. A square cubic column microstructure of InAs material combined with Ti material was added to the substrate structure of Case 1 (square cubic column microstructure model). In Figure 5b, the whole absorptions of the microstructure-free models are all unsatisfactory, with all of them below 60% in the 800–4000 nm waveband range, and none of them above 80% in the entire 280–4000 nm band range. When titanium hollow cylindrical microstructures are added to the microstructure-free model (as in Case 2), there appears to be an overall significant increase in the model’s absorption, which exceeds 90% in the 280–2300 nm waveband. The comparison of the absorption of these two models shows the great role of the microstructure in improving the absorption of this capture device. By adding one layer of InAs hollow cylindrical microstructures on the top of Case 2, the model’s absorption shows a significant increase in both the 540–1500 nm band (an increase in absorption of about 5% or so) and a small increase in the 1500–2900 nm band (an increase in absorption of about 0.5% or so) compared to the Case 2 model, which is attributed to the absorption effect of the nano-semiconductor InAs and the blue-shift effect of the absorption waveband because of the quantum-limited domain effect. Meanwhile, the model’s absorption in the 280–540 nm waveband has a small decrease compared with that of the Case 2 model, which is because the increase in the thickness of the microstructure affects the transmission of the short-wavelength light wave and its interaction with the model. However, depending on the spectrum of solar radiation, solar energy is mostly focused in the visible and near-infrared wavebands, so the introduction of the top-layer InAs microstructure really improves the absorption properties of this model in both the visible and near-infrared wavebands. The lower absorption in the UV and visible wavelengths of the solid cylindrical microstructures of Case 4 compared to the hollow cylindrical microstructures suggests that the structural features of the hollow core do contribute to the enhancement in the model’s absorption. It is also compatible with the previous analysis of the model’s physical absorption mechanism, in which the coupling of excitons and light waves occurring on the inner side of the hollow cylindrical microstructures further improves the absorption of the model in the UV and visible wavelengths [57,58]. The overall absorption performance of the square cubic column microstructure model in Case 5 is slightly worse than the solid cylindrical microstructure model. The absorption in the 2300–3000 nm waveband is better than that of the other models, but this is not very meaningful for the absorption of sunlight. Therefore, the comparison of the absorption of three different microstructure models in Cases 3, 4, and 5 shows that the hollow cylindrical microstructure model presented in this paper has a certain geometrical superiority. It can be observed from Figure 5c that compared with the topless InAs microstructure layer, the Case 3, 4, and 5 models show an increase in absorption due to the addition of the top InAs microstructure. This is owing to the resonant coupling in which excitons are coupled to the light wave of the nano-semiconductor InAs material in this waveband, and the resonance absorption is added to the original absorption. The positions of resonance absorption peaks are also different due to the different shapes, and the resonance absorption peaks of the exciton and the light wave of the Case 3, 4, and 5 counterparts are at 697.3 nm, 714.8 nm, and 729.7 nm, respectively. Figure 5d shows the reflectivity of five different structural models in the 280–20,000 nm waveband. From the graph, it can be learned that the model substrate makes the main contribution to the high reflectivity properties in the thermal infrared waveband. With the addition of microstructures, the reflectivity of the model in the thermal infrared waveband decreases, which is due to the absorption of thermal infrared waves by the microstructures. The models of Cases 2, 3, 4, and 5 all show special reflectivity minimums near the wavelength of 4300 nm. Comparing the reflectivity of the five models, the Case 1 model does not show this reflectivity minimum, but it appears after the addition of the Ti material microstructure. Cases 2 and 3 are Ti hollow cylindrical microstructures, so the reflectivity minimums are almost equal, while Cases 4 and 5 have different Ti material microstructures so the reflectivity minimums have a difference in the size of the reflectivity minimum. It can be concluded that the reflectivity minimums are caused by the absorption peaks of the Ti material microstructure.

3.5. Effect of Different Structural Parameters

Changes in structural parameters also have the potential to significantly alter the model’s absorption properties. To investigate the effect of changing this model’s structural parameters on its absorption performance and to find the appropriate structural parameters, the effect of changing the outer radius (R) and inner radius (r) of the model’s hollow cylindrical microstructure on its absorption is analyzed and discussed in this paper. Normally, the more data points taken, the more accurate the analysis results. However, considering that a simulation takes a lot of time, a large number of data points will undoubtedly greatly increase the time cost. Therefore, this paper adopts a large interval for the simulation values, and by analyzing the more appropriate data in the simulation results, and then taking those data as the center of a smaller data interval for scanning and calculation, we can more accurately see the trend of the data, so as to choose a more appropriate value of the structural parameters [59,60]. When the optimal inner radius value was not determined at the beginning, the inner radius parameter was set to 0 nm in this paper to investigate the effect of the change in the outer radius on the absorption of this model and to find the optimal outer radius parameter. In Figure 6a, with a 50 nm length interval taken from 0 nm to 200 nm, the overall absorption in the 280–2800 nm waveband shows an increasing and then decreasing trend with the growth in the outer radius. This model with an outer radius of 100 nm shows the best absorption in the visible and near-infrared bands [61,62]. To study the effect of the outer radius size on the model’s absorption more closely, and in order to take a more optimal outer radius structural parameter, this paper also takes 100 nm as the center, and conducts a scanning simulation of the absorption in the range of outer radius values from 60 nm to 140 nm. In Figure 6b, the model’s absorption in the UV waveband decreases slightly as the outer radius increases, while the absorption in the IR waveband increases with the outer radius. For consideration of solar radiation energy spectral distribution and absorption requirements, 130 nm was selected as the parameter value for the outer radius (R).

It was determined that the fixed outer radius R has a value of 130 nm. The inner radius (r) is then discussed. As shown in Figure 7a, with a 20 nm length interval taken at 0–100 nm (considering the process complexity, the inner radius is only taken to be 100 nm at the maximum), it can be observed this model’s absorption in the UV, visible, 700–1200 nm, 1350–2100 nm, and 2800–4000 nm wavelength bands increases with growing inner radius, and the absorption in the 2150–2800 nm bands decreases slightly with increasing inner radius. Overall, the larger the inner radius, the better the absorption performance of the model [63,64]. To study the effect of the inner radius size on the model absorption more closely, and to take a better inner radius structural parameter, this paper also conducts a scanning simulation of the absorption in the length range of the inner radius taking the value of 80–100 nm. In Figure 7b, the model’s absorption in the infrared wavelength wavebands mainly decreased and then increased with growth in the inner radius in the length range of 88–92 nm, and the absorption in the ultraviolet and visible wavelength wavebands increases slightly with growth in the inner radius. For consideration of the solar radiation energy spectral distribution and absorption requirements, 96 nm was selected as the parameter value of the inner radius (r).

3.6. Angular Sensitivity Analysis

Figure 8a reveals that when the polarization angle of the incident light is altered from 0 to 90 degrees, the model’s absorption remains almost unchanged, which means that the model is highly polarization-insensitive. Because of the highly symmetric structure, this model essentially has the same absorption of incident light at all polarization angles [65,66]. Because humans live mostly within 60 degrees of latitude between the North and the Equator, this paper only considers the model’s absorption case when the angle of incidence of sunlight is between 0 degrees and 60 degrees. Figure 8b reveals that the absorption in the ultraviolet and visible wavelength ranges does not obviously change with the growth in the incidence angle of sunlight, and the absorption grows within 1000–4000 nm, so the capture device has very good wide-angle absorption characteristics [67,68,69,70]. In summary, the capture device has excellent wide-angle absorption properties and polarization insensitivity.

4. Conclusions

This paper presents a broadband solar capture device based on the top microstructure of semiconductor InAs material. The quantum-limited domain effect of the semiconductor nanomaterials is utilized to further enhance the absorption performance of the model. The model is fabricated from top to bottom with hollow cylindrical microstructures made of semiconductor InAs material with Ti material at the top, and a combination of SiO₂ material film, Ti material film, and Cu material film as the substrate. Simulations of the model using FDTD Solutions software show an average absorption of 96.15% in the waveband from 280 nm to 2500 nm, and a weighted average absorption of 97.71% in the waveband from 280–4000 nm under AM1.5 conditions. The model has a certain spectral selectivity as the reflectivity is greater than 80% in all wavebands of wavelengths 7940–20,000 nm, which makes the model more resistant to thermal radiation. In addition, the model achieved a thermal radiation efficiency of 94.40% in the waveband range of 280–2500 nm when used as a thermal emitter. This paper also discusses the physical mechanism of broadband absorption using electric field distribution diagrams and argues that the model has certain structural superiority by comparing different structural models. The effect of the change in structural parameters on the absorption performance of the model is also analyzed. Finally, the scanning simulation of the model’s absorption changes under different polarization angles and incidence angles demonstrates that the model has excellent polarization insensitivity and wide-angle absorption properties, and has high potential for practical applications.