Analyzing and Exploring a Model for High-Efficiency Perovskite Solar Cells ()
1. Introduction
In the field of photovoltaics, the investigation of CSSnCl3 perovskite type for solar cell applications has become an interesting area of study [1] [2] . A lot of interest has been spent on perovskite solar cells (PSCs) because of their high power conversion efficiency (PCE) and inexpensive manufacturing methods [3] [4] [5] . PSC performance and stability can be further enhanced by using materials of the CSSnCl3 perovskite type, which is an exciting prospect [6] [7] . Materials of the CSSnCl3 perovskite type offer special qualities that make them appropriate for use in solar cells. Because of the tunable bandgaps made possible by their crystal structure, they can effectively absorb light over a large portion of the solar spectrum. This wide absorption spectrum increases the solar cell’s total energy conversion efficiency and maximizes the use of incident sunlight [3] [8] . The high charge carrier mobility and diffusion lengths of CSSnCl3 perovskite-type materials, in addition to their tunable bandgap, are essential for effective charge transport inside the solar cell device. These characteristics help to minimize recombination losses and enhance device performance by enabling the effective collection and extraction of photogenerated charges [1] [9] . The low cost and solution-processability of CSSnCl3 perovskite-type materials are additional advantages. In comparison to conventional silicon-based devices, large-scale manufacture of solar cells is possible thanks to easy and scalable fabrication techniques like spin-coating and inkjet printing. The CSSnCl3 perovskite-type materials have the potential for commercialization and wide-scale use of solar energy technologies because of their affordability [2] [10] .
These previous studies indicate that additional research is required to fully understand the potential of CsSnI3 as an active component in solar cells [1] - [10] . So, a thorough examination of CSSnCl3 perovskite-type solar cells’ electrical characteristics is required to fully understand their potential. This examination includes investigating their series and shunt resistance as well as the absorber, and buffer layers. Examining these qualities offers important insights into the elements influencing the functionality, effectiveness, and long-term stability of the technology. We aim to broaden our understanding of the characteristics of CSSnCl3 perovskite-type materials and exploit their full potential for efficient and economical solar energy conversion. With the use of the knowledge obtained through this study, high-performance perovskite solar cells may be designed and made, aiding in the creation of renewable and sustainable energy sources.
2. Simulation Methodology
The numerical simulation program, 1D-SCAPS (version 3.3.05), has been utilized extensively for the theoretical study of 1D solar cells which was developed by the Electronics and Information Systems Department at the University of Gent in Belgium (ELIS) [8] [9] [11] . The data of solar cell absorption materials parameters used in the simulation are displayed in Table 1. This simulation tool enables examination of the transport properties of various crystalline, amorphous, or polycrystalline solar cell materials, including bulk flaws and interfaces, by solving the Poisson equation for both electrons and holes at the interface and between the different layers of the device structure. To numerically model the thin-film solar cell, optical and electrical properties of each layer were obtained from literature sources, with simulation parameters set to a working temperature of 300 K and 106 ohms in series resistance and 1 ohm in shunt resistance, respectively. Figure 1 depicts the simulated solar cell device, which is made up of layers of Al:ZnO, ZnO, CdS, CsSnCl3, and MoS2, with Al:ZnO serving as the window layers, CsSnCl3 perovskite serving as the absorber layer, CdS serving as the buffer layer, and MoS2 serving as the back contact. The work function was considered as a flat band in the entire simulation, with SCAPS automatically
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Figure 1. The suggested perovskite solar cell.
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Table 1. Solar cell absorption materials parameters used in the simulation [1] [13] [14] [15] [16] .
computing the work function to establish an ohmic contact [12] . It should be emphasized that this simulated study did not take the effect of dangling bonds on material contacts.
The parameters of the window layer, buffer layer, and back contact materials are presented in Table 2 [12] , where the data of solar cell absorption materials parameters used in the simulation can be found.
3. Results and Discussions
We conducted an analytical study of the CsSnCl3 perovskite solar cell. The primary focus of the study was to investigate the electrical property of the cell and their relationship with series and shunt resistance, the absorber layer, the buffer layer, acceptor density, and the temperature. The device structure used in the
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Table 2. Window layer, buffer layer, and back contact materials parameters are used in the simulation [12] .
study was a hetero-structure of Al:ZnO/ZnO/CdS/perovskite and MoS2.
Two important factors, series resistance (Rs) and shunt resistance (Rsh), affect a solar cell’s electrical characteristics. In this part, we examine how series and shunt resistances affect electrical properties. The effects of series resistance are examined in power conversion efficiency (PCE), short circuit currant (Jsc), open circuit voltage (Voc), and fill factor (FF) in Figure 2. Here, the series resistance changes from (0 - 6) Ohm.
As series resistance rises, the fill factor and power conversion efficiency decline. The resistance in the conducting medium of the solar cell is referred to as the series resistance, which includes the resistance of the materials and connections. As current passes through it, it causes a voltage to drop, which lowers power production and efficiency.
The short current density remains constant even though the series resistance rises but the open voltage rises up to 1.1422 volts.
Figure 3 shows how RSh affects in the range of 0 - 107 Ohm. Figure 3 shows the significantly different PV parameter values for VOC, JSC, FF, and PCE for various shunt resistances. When RSh rises from 0 to 2 × 106 Ω·cm2, all characteristics increase dramatically.
The PCE reached the highest value of 27% at RSh of 2 × 106 and remained constant up to 107 Ω·cm2 or beyond RSh. The primary origin of RSh is the defects formed during the manufacturing process. The structure becomes a low-resistance path for current flow at a higher RSh value. Herein, the VOC increased with shunt resistance up to 1.1 volts while the JSC was found up to 27 mA/cm2.
These results agree with other papers that study the resistance effect on other suggested cells with different layers but with better results for this cell [1] .
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Figure 2. Effect of series resistance on various electrical characteristics (a = 0.6 µm, c = 1 µm, b = 0.8).
3.1. Buffer Layer Analysis
When used as a buffer layer in solar cells, cadmium sulfide (CdS) has a variety of effects on the electrical characteristics. First, due to the energy band structure’s capacity for proper energy level alignment, charge carrier extraction and injection at interfaces are made possible. Additionally, CdS aids in the creation of electron-hole pairs by absorbing visible light. A steady current flow is ensured by the high electron mobility of CdS, which enables efficient electron transport from the light-absorbing layer to the electrode. In addition, CdS functions as a surface passivation layer, lowering charge carrier recombination at interfaces and enhancing carrier lifespan. Additionally, CdS serves as a buffer between the transparent conducting oxide electrode and the light-absorbing layer, maximizing energy level alignment, enhancing carrier extraction, and decreasing interfacial barriers [17] [18] . The actual effect of CdS on electrical characteristics depends on several variables, including its thickness, the process used for deposition, and the components and structure of the solar cell.
Here, the effect of the buffer layer’s thickness on a solar cell parameter with various absorber layer thicknesses has been investigated. Figure 2 illustrates the
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Figure 3. Effect of shunt resistance on various electrical characteristics (a = 0.6 µm, c = 1 µm, b = 0.8).
impact of changing the buffer layer’s thickness on the performance of the solar cell.
Figure 4 shows that the Jsc, and Voc are essentially constant concerning the thickness of the buffer layer but PCE, and FF decrease. To reduce the series resistance, buffer layers should generally be as thin as possible. Low charge separation between the photogene-rated carriers is caused by the very thin buffer layer’s tiny space charge width [12] . A very thin buffer layer also causes a greater leakage current. This is seen in PCE results with a buffer layer ranging in thickness from 0.02 to 0.08 nm.
The effect of the buffer layer doping concentration on solar cell characteristics with three different absorber layer thicknesses is examined in this section. The solar cell’s output performance changes in Figure 5 when the buffer layer’s doping concentration (measured in cm−3) increases. From Figure 5, it can be seen that
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Figure 4. The variation of buffer layer thickness and corresponding change in electrical parameters of solar cell (a = 0.6 µm, c = 1 µm, b = 0.8).
the electrical parameters FF and Voc with different solar cell device structures change relatively little as the electron concentration varies (3 × 1018 to 9 × 1018). As concentration rises, PCE, and Jsc decline.
Increasing the doping concentration of CdS as a buffer layer in a solar cell can lead to a decrease in the power conversion efficiency (PCE) and short-circuit current (Jsc). This can be attributed to several factors. Firstly, higher doping concentrations introduce additional defects and recombination centers, increasing the rate of charge carrier recombination and reducing the overall efficiency of the device. Secondly, increased doping can elevate the series resistance within the solar cell, impeding the flow of current and resulting in a lower Jsc [19] . Additionally, excessive doping can alter the optical properties of the CdS layer, limiting the absorption of photons and reducing the generation of electron-hole pairs, leading to a decrease in Jsc. Lastly, higher doping concentrations may also reduce the carrier mobility within the CdS layer, hindering the efficient transport of charge carriers and resulting in a lower Jsc [20] [21] [22] . Therefore, optimizing the doping concentration is crucial to maintaining high PCE and Jsc in
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Figure 5. The impact of buffer layer doping concentration (a = 0.6 µm, c = 1 µm, b = 0.8).
CdS-based solar cells.
3.2. CSSnCl3 Absorber Layer Analysis
Figure 6 illustrates the impact of temperature on various electrical parameters, where it can be observed that an increase in temperature causes a decrease in both Voc and FF, while PCE and Jsc remain unaffected. The open-circuit voltage is the parameter most affected by the temperature increase, following previous studies that highlight the dependence of photovoltaic solar cells on temperature sensitivity and open-circuit voltage [12] . Higher-voltage solar cells exhibit less temperature sensitivity, which emphasizes the importance of considering the open-circuit voltage when assessing a solar cell’s temperature performance.
The presence of an acceptor impurity in the CSSnCl3 absorber layer, along with any lack of stoichiometry or flaws in the synthetic material, determines the concentration of the carrier.
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Figure 6. Contour graph the variation of CSSnCl3 cell performance with temperature and the thickness of the absorber layer.
In Figure 7, the influence of the absorber layer’s thickness and doping concentration on the electrical characteristics of solar cells is illustrated. It can be observed that augmenting the doping concentration does not affect the electrical parameters. However, increasing the absorber layer’s thickness enhances the internal electric field of solar cell devices, which is advantageous for achieving better values of the solar cell’s Voc, Jsc, and PCE.
4. Conclusion
The performance of CsSnCl3 perovskite-type devices was evaluated using SCAPS-1D simulations with an AM 1.5G solar spectrum and an operating temperature of 300 K. In these simulations, the effects of resistance, temperature, doping concentrations in the absorber and buffer layers, and the thickness of the layers on the PV properties of the devices were investigated. Increasing the doping concentration of CdS as a buffer layer in a solar cell can lead to a decrease in the power
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Figure 7. The effect of the thickness and acceptor density of CSSnCl3 on the solar cell electrical properties.
conversion efficiency (PCE) and short-circuit current, increasing the absorber layer’s thickness enhances the internal electric field of solar cell devices, which is advantageous for achieving better values of the solar cell’s Voc, Jsc, and PCE. Al:ZnO/ZnO/CdS/CsSnCl3 and MoS2 hetero structures make up our design, which outperforms the others with a very good reported Power conversion of 26.15%.