Examining the effect of temperature and thicknesss on polycrystalline semi-conductor CIGS solar cell

Abstract

Keywords: CIGS; Efficiencies; Numerical Simulation; SCAPS 1D

Introduction

Energy is essential for life. It is the driving force behind all physical and biological processes. Energy is the very foundation of our modern world, indispensable for powering our homes, businesses, and the vital services that keep us healthy and informed. Renewable energy is an energy which comes from natural environment, such as rain, sunlight, wind, geothermal heat, waves, tides. That is crucial since renewable energy sources can help us to meet our growing energy needs while decreasing our reliance on fossil fuels and struggling climate change. Renewable energy sources most common wind, sunlight is free all over the world, and they can be used to generate electricity 24/7. Solar panels can convert the sunlight into electricity, which can be used in industry and homes. There are many studies about solar energy. Govindasamy and Kumar. [1] performed an experiment for rising the effectiveness of solar cells using composite materials with phase change. They examined that solar panel efficiency decreases as temperature increases. Phase change materials (PCMs) can be used to keep solar panels cool, which improves their efficiency. PCMs are substance that is able to absorb and set free heat at a specific temperature. When used in solar panels, PCMs can help to keep the panels cool, which improves their efficiency. They used four different PCMs. Paraffin jelly alone, Paraffin jelly with expanded perlite, Paraffin jelly expanded graphite, Parafin jelly expanded vermiculite. The study found that the paraffin jelly with expanded perlite PCM was reduced the biggest surface temperature of the solar units by 10.29 °C. It also increased the electrical efficiency of the solar panels by 2.92% and the power output by 8.04%. The results showed that the paraffin jelly with expanded perlite PCM was the most effective at reducing the temperature and improving the efficiency of the solar panels. Guesmi et al. [2] investigated CCTS-based solar cell’s performance, which have received less attention than CZTS-based solar cells. The CCTS thin film was formed in substrate of glass by thermal evaporation and then operated on SCAPS 1D software to simulate the acts of a CCTS based solar cell. It was found that the CCTS film had big coefficient of absorption is 104 and energy of bandgap is

Materials And Methods

Numerical Methods SCAPS 1D is a one dimensional solar cell simulation which the version is 3.3.11. This software is free to use to the Photovoltaic research association such as universities and research institutes, companies [21] [22]. The researcher can create a solar cell which can be various proterties with layers which can be seven; such as temperature, optical absorption, thickness, defect densities etc. And software is able to show that the measurements of: I-V, Q-E, C-f, C-V. Solar Cell Capacitance Simulator (SCAPS 1D) software’s working fundamentals are related to steady state electron hole continuity equations and Poisson. The Poisson equation is shown in (1).

(1) φ represents the electrostatic potential at position x , q + denotes the electron charge N D indicates the number of positively charged donor atoms per unit volume which is ionized − donor concentration, NA represents the number of positively charged donor atoms per unit volume which is ionized acceptor density, the terms of p and n represents separately electron density and hole density, ε0 and εr stands for permittivity of free space and relative permittivity of the semiconductor material, pt represents the trapped hole density at position x, nt stands for the trapped electron density at position x and (x) denotes the position in the x-coordinate system. (2) (3) Equations (2) and (3) describe the steady-state continuity relations for electrons and holes. In simpler terms, they express how the concentrations of these charge carriers vary within the material over time. Such variations arise from three main processes: the inflow and outflow of carriers, their generation under illumination, and their recombination within the semiconductor. In these expressions, Jn and Jp denote the current densities of electrons and holes, respectively, R represents recombination processes (both direct and indirect), and G indicates the carrier generation rate. (4) (5) The symbols µn and µp represent the mobilities of electrons and holes, while Dn and Dp denote their corresponding diffusion coefficients. The term E refers to the electric field acting within the semiconductor. The overall current in a semiconductor results from the combined effects of two fundamental transport mechanisms: drift and diffusion. The drift component describes the motion of charge carriers under the influence of an external electric field, whereas diffusion accounts for their movement from regions of higher concentration to lower concentration. Equations (4) and (5) express these principles mathematically for electrons and holes, respectively. The optical absorption constant α: (6)

The optical absorption coefficient (α) is a basic property that tells how much light a material can take in at different wavelengths. In solar cell studies, α plays a key role because it directly affects how well the device absorbs sunlight and turns it into electricity. Equation (6) shows how the absorption coefficient (α) relates to the photon energy (hν) and the material’s band gap (E_g). The constants A and B change from one material to another. In simple terms, α isn’t a fixed value—it moves up or down depending on the energy of the incoming photons. When the photon energy goes beyond the band gap (hν > E_g), the material absorbs light strongly, creating plenty of charge carriers. But if the photon energy is lower (hν < E_g), absorption becomes weak, and the material is almost transparent to that light.In our work, this equation was used to describe how the CIGS layer absorbs light under real conditions. Considering that α changes with wavelength made the simulation more realistic and gave a clearer idea of how light actually behaves inside the cell. This also made the overall performance analysis more dependable. Theoretical Background Solar cell’s characteristic is simply related to the I-V graph measurements. It shows that open circuit voltage (VOC) , short circuit current (ISC), voltage –current-power at maximum power point , fill factor (FF) and efficiency.Short circuit current (ISC) is the maximum current that a solar cell can generate when its terminals are directly connected, essentially bypassing any load or resistance. In this scenario, the voltage across the cell is essentially zero. Open circuit voltage (VOC) is the maximum voltage that a solar cell can produce when no current is flowing through it. It’s essentially the theoretical voltage difference between the cell’s positive and negative terminals under ideal conditions with no load connected. The maximum power point (Pmax) is that the solar cell can generate its maximum power; in this case the current and voltage defines as Imax and Vmax. The fill factor (FF) (7) is a parameter that in conjunction with VOC and ISC determines the maximum power from a solar cell. Efficiency is quantified as the quotient of Pmax divided by the input light irradiance (E) and the surface area Ac of solar cell. (7) (8) If you look at Figure 1, the I–V curve basically shows how a solar cell reacts when the light or temperature changes. It’s the main way to see how well the cell works and where it delivers the most power. The shape of this curve isn’t fixed — it varies with the type of technology used, whether that’s a crystalline-silicon panel, a thin-film design, or some newer photovoltaic setup. At the short-circuit point, the voltage drops to zero while the current reaches its peak. That’s the maximum

Figure 1. The solar I-V curve visually illustrates the operational behavior of a specific solar cell. current you can get when the cell’s terminals are directly linked together. In the opposite case, the open-circuit point, the current becomes zero and the voltage climbs to its highest value. This is the greatest voltage the device can produce when there’s no external load connected. Between these two limits lies what’s called the maximum power point (Pmax) — the spot where the product of current and voltage gives the highest output. Knowing this point is crucial for figuring out how efficient the cell really is and for setting its best working conditions in practice.

Device Structure and Simulation Parameters The development of PV technology has caused to a rise in simulation models and tools. These simulation applications can estimate and approach the simulation of monocrystalline, polycrystalline and matters based on solar cells. Among those simulation softwares, the SCAPS-1D simulator is one of the softwares withan advanced algorithm that takes into account the higher number of parameters. In this study, we used CIGS based photovoltaic panels. In figure 2 illustrates the structure’s the schematic employed in this simulation.

Figure 2. The model’s representation that used for the Photovoltaic simulation on SCAPS 1D, four layer structures were chosen.

Table 1. Material properties date for simulating the CIGS solar cell layers CIGS

Results And Discussion

Temperature (K) and Thickness (um) Effects In this part of the experiment, the effects of the temperature and thickness on efficiency of the solar panel has been investigated. Table 2 demonstrated the distribution of the temperature and thickness used in this study. To clarify the dominant parameter affecting performance, Table 2 has been examined in detail. The data obtained from Table 2, which reveals that temperature has a more significant impact on CIGS solar cell efficiency than thickness within the investigated ranges. Specifically, increasing the temperature from 200K to 350K at a constant thickness results in a substantial decrease in efficiency (around 9.7%), while varying the thickness from 1µm to 5µm at a constant temperature leads to only a minor change (around 0.02%). This highlights the critical role of temperature control in optimizing CIGS solar cell performance. Our detailed simulations, summarized in Table 2, the operated I-V parameters Jsc (mA/cm2), Voc (V), Fillfactor FF and solar cell efficiency η (%) of single shot at different thicknesses and temperatures for indium gallium selenide (CIGS) solar cell under lighting, that the CIGS solar cell’s best experiment values with open circuit voltage, short circuit current density, fill factor and efficiency is 0.558731V, 31.75017336 mA/cm2, 61.3, and 10.8845 % at 3.0000µm and 300K respectively. However, simulation show has been showed at 300K, 1.000 µm open-circuit voltage, short-circuit current density, fill factor and efficiency is 0.558663 V, 31.68649100 mA/cm2, 61.4 %, and 10.8697 % at same temperature and 2000 µm open-circuit voltage, short-circuit current density, fill factor and efficiency is

Table 2. I-V curve parameters simulated (V), (mA⁄cm2), eta and FF (%) is calculated in single shot at different temperatures (K) and thicknesses (μm) for indium gallium selenide (CIGS) solar cell under lighting Thickness (μm)

0.558703 V, 31.72554985 mA/cm2, 61.3 %, and 10.8797%. Buffing layer thickness caused to a few rise in efficiency as like, at 4.000 and 5.000 µm respectively open-circuit voltage, short-circuit current density, fill factor and efficiency is 0.558752 V, 31.72554985 mA/cm2, 61.3 %, and 10.8869 % and 0.558769V, 31.78243479 mA/cm2, 61.3%, and 10.8881 %. Comparing to 200K the greater values single shot at 5.000 µm is open-circuit voltage, short-circuit current density, fill factor and efficiency is 0. 811240V, 32.60452643 mA/cm2, 65.3 %, and 17.2776 %. So these values tell us that greater values at 200K compared to 300K. The worst values compared to other temperature parameters is at 350K at 1.000 µm with open-circuit voltage, short-circuit current density, fill factor and efficiency is 0.428152V, 31.09036540 mA/cm2, 56.5, and 7.5342 %.The performance of the CIGS solar cell was examined under various temperature and thickness conditions. The best results were obtained at 300 K with an absorber thickness of 3.0 µm, where the device produced an open-circuit voltage (Voc) of 0.5587 V, a short-circuit current density (Jsc) of 31.75 mA/cm², a fill factor (FF) of 61.3%, and an overall efficiency of 10.88%. As the temperature increased, charge carriers gained kinetic energy, which led to more frequent collisions and recombination events. This behavior caused both the current and the overall efficiency to drop. In contrast, increasing the absorber thickness improved light absorption but also

raised internal resistance, resulting in additional losses. The relatively stable fill factor across all conditions reflects the electrical stability of the simulated device. Choosing 300 K as the reference temperature in SCAPS-1D simulations was not arbitrary—it reflects a balance between practicality and performance. At this temperature and thickness (3 µm), the solar cell reached its best combination of Voc, Jsc, FF, and efficiency, aligning closely with typical room-temperature conditions. Because most experimental measurements are performed near 25 °C (≈ 298 K), the difference between simulations and real-world data remains minimal. Even slight deviations—on the order of only a few millivolts in Voc—do not significantly affect accuracy. Thus, 300 K serves as a reliable benchmark for both modeling and laboratory validation. The nearly constant fill factor of about 61% further confirms that the CIGS device maintains electrical consistency across these operating conditions. When you look closely at the results, it becomes clear which factors shape how the device behaves. The interaction between temperature and thickness is especially important because it lets engineers tweak the design of CIGS cells for better output without pushing up manufacturing costs. Temperature changes affect carrier mobility and recombination, while thickness alters how light is absorbed and how much internal resistance builds up. Getting the balance right between the two is what makes the cell perform

well. Interestingly, the data around 300 K fits real industrial conditions quite well, so it serves as a good and repeatable reference point for optimization. Efficiency, noted as η, is still the simplest way to judge how well a solar cell converts sunlight into power. When the cell heats up, η usually drops because the current– voltage (I–V) curve starts to distort. Higher temperatures lower both Voc and Isc, which means less power overall. The effect of thickness is a bit more complicated. A thicker absorber grabs more photons and raises current, but it also adds resistance and slightly pulls voltage down. Thin layers do the opposite — better voltage, weaker current. So, finding a middle ground between the two is what really pushes efficiency upward. In general, how temperature and thickness interact sets the limits of what a CIGS device can do. The simulations here show that decent efficiency can be reached even with minimal material use, as long as structural and thermal settings are properly adjusted. The absorber layer matters the most: if it’s thinner than about 3 µm, it doesn’t take in enough light; if it’s thicker, resistance grows and carrier flow slows down. Around 3 µm seems to be the sweet spot, since making it thicker doesn’t bring much benefit. The band gap of the absorber also plays a big role. Making the band gap wider cuts down photon absorption and current, but it slightly raises Voc because voltage scales with band gap energy. In this case, tuning the band gap carefully brought the efficiency up to roughly 17.2%, showing that band-gap engineering can really boost CIGS performance when done within realistic limits. Overall, these findings point toward a clearer way to design efficient yet affordable CIGS solar cells. By understanding how temperature and thickness work together and adjusting material properties accordingly, it’s possible to push the technology much closer to its theoretical best while still keeping production practical and cost-effective.

Conclusion

The CIGS solar cell was comprehensively simulated and analyzed using SCAPS-1D (version 3.3.11) under varying temperature and thickness conditions, as detailed in Table 1 and Figure 2. Among all the cases examined, the most favorable performance was achieved at 300 K with a layer thickness of 3.0 µm. Under these conditions, the device reached a short-circuit current density (Jsc) of 31.75 mA/ cm², an open-circuit voltage (Voc) of 0.5587 V, a fill factor of 61.3%, and an efficiency of 10.88% under illumination. These results clearly indicate that both temperature and absorber thickness play decisive roles in defining the electrical response of CIGS solar cells. To ensure the validity of our findings, we compared them with the experimental and numerical studies by Laseide and Ramere (2021) and Patil et al. (2023), both of which investigated similar temperature- and thickness-related effects on photovoltaic efficiency. The observed

patterns were consistent. For instance, our simulations showed a noticeable drop in efficiency—from 17.2% to 7.5%—as the temperature increased from 200 K to 350 K, whereas Laseide and Ramere reported a comparable but smaller decline (from 14.8% to 13.5%) over a 7 °C temperature rise. This alignment not only supports the reliability of our simulation but also situates our work within a broader, experimentally validated context. By contrasting our results with those in the literature, we emphasize both the robustness of our data and the distinct contribution of this study to ongoing CIGS research. The results show that pushing either temperature or layer thickness too far hurts the solar cell’s performance. When the temperature rises too much, carrier recombination speeds up; when the absorber layer gets thicker, more defects form and internal resistance goes up. Both effects lower the open-circuit voltage (Voc) and short-circuit current (Jsc), which together drag down overall efficiency (η). To avoid that, the fabrication steps have to be carefully tuned—especially the absorber thickness and processing temperature. Keeping that balance not only improves efficiency but also makes the device more durable and easier to reproduce in manufacturing. Our efficiency values are close to those reported in earlier work on polycrystalline cells [17], but this study looks at the combined effect of temperature and thickness over a wider range (200 K – 350 K and 1 µm – 5 µm). The data make it clear that both factors depend on each other: temperature has the stronger impact, while thickness changes the outcome more subtly but still measurably. The best results showed up again near 3 µm, confirming that making the layer any thicker adds little or no benefit. Overall, these findings give useful direction for improving how CIGS solar cells are built and operated. Using simulation tools such as SCAPS-1D helps make sense of the complicated behavior inside multilayer solar devices. This kind of modeling links theory and real experiments, helping researchers predict performance more accurately. In the end, it can cut testing costs, speed up material development, and support cleaner, more efficient, and affordable photovoltaic systems.

Scaps

Copper Indium Gallium Selenide Open-Circuit Voltage, V Short-Circuit Current Density, mA/cm$^2$ Fill Factor, % Efficiency, % Temperature, K Micrometer Solar Cell Capacitance Simulator Zinc Oxide Cadmium Sulfide Molybdenum Indium Tin Oxide

Data Availability Statement

The authors confirm that the data that supports the findings of this study are available within the article. Raw data that support the finding of this study are available from the corresponding author, upon reasonable request.

Conflict Of Interest

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Ethics

There are no ethical issues with the publication of this manuscript.

Statement On The Use Of Artificial Intelligence

Artificial intelligence was not used in the preparation of the article.

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