The primary goals of this project are to analyze the structure and assess the photovoltaic performance of n-i-p structured formamidinium tin iodide (FASnI3) perovskite solar cells at different operating temperatures to inspect the impact of operating temperature on device performance using a Solar Cell Capacitance Simulator (SCAPS). The simulated device structure is Au/spiro-OMeTAD/P3HT/FASnI3/PCBM/TiO2/FTO, whereas spiro-OMeTAD and TiO2 serve as the hole transport layer and electron transport layer, respectively. SCAPS simulation has been performed at 200, 300, 400, 500, and 600 K operating temperatures, and corresponding current density vs voltage (J–V) characteristics have been studied in addition to the photovoltaic metrics, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and power conversion efficiency (PCE). The thickness fluctuation and doping concentration variation of the absorber layer and the electron affinity variation and thickness variation of the Hole Transport Layer (HTL) and Electron Transport Layer (ETL) under temperature variation were also examined analytically. It has been found that there is an inverse relationship between temperature and power conversion efficiency (PCE). The extended thickness of the absorber layer enhances the PCE and JSC. Temperature variations in the thickness of the ETL and HTL have a minimal effect on the PCE and JSC of the device. At standard room temperature (300 K operating temperature), the solar cell parameters are found to be a short-circuit current density (JSC) of 17.93 mA/cm2, open-circuit voltage (VOC) of 1.06 V, fill factor (FF) of 67.46% and power conversion efficiency (PCE) of 17.93%.
I. INTRODUCTION
Energy sustains life, empowers technology, fuels daily routines, and drives economic prosperity. Its applications range from transportation to healthcare, underlining its indispensable role in contemporary society’s functioning and advancement. Users search for a variety of sources to discover an eco-friendly energy source. The emission of solar energy from solar cells is among the sustainable sources. Solar cells use sunlight to produce clean, renewable electricity, eliminating the need for fossil fuels and lessening the impact on the environment. They provide environmentally friendly energy generation that powers buildings, residences, and even grids, preventing climate change and creating a better, more sustainable future.
Through the photovoltaic effect, solar cells turn sunlight into electricity. When photons from the sun hit the solar cell, they knock electrons out of the semiconductor material and start an electric current. After that, this direct current (DC) is changed to alternating current (AC) for usage in residences and commercial buildings. Perovskite material-dependent solar cells became popular because of this discovery. Even though the initial effective solid-state perovskite cells were not discovered until mid-2012, development moved incredibly quickly in 2013, with energy conversion efficiency having reached a verified 16.2% by the year’s end. At the beginning of 2014, this improved to a known efficiency of 17.9%, including unverified figures as much as the claimed 19.3%.1
Huge research efforts are currently focused on this technology because of the high power conversion efficiency (PCE) and the potential of this element to operate as the upper device in a tandem (multijunction) solar cell construction, placed above a traditional bottom device made of silicon or copper indium gallium diselenide (CIGS).2,3 The three main issues that currently stand in the way of innovation in the industry are (1) scaling up the manufacturing procedures to broad regions, (2) the toxicity of the solvents and lead that are still necessary for high-performance Perovskite solar cell (PSC) operations for manufacturing, and (3) the material’s sustained consistency.4 Inkjet technology and vacuum placement are interesting substitutes for solution processing, which is still the most widely used deposition method.5–8 In addition, according to recent findings, less dangerous solvent alternatives to routinely used harmful solvents such as dimethylformamide exist.9 However, lead-free PSCs have not progressed at all, exhibiting low PCE to date.10 While the tandem solar cell perception discussed above is where this issue is most crucial, single-junction PSC devices should still be aware of it because the power expense with leveling is substantially centered on the lifespan of the power source. Because of the four main environmental stressors on a solar module—oxygen, humidity, light, and temperature—achieving high PSC is difficult.11–15 Because PV systems’ power outputs decrease as their temperatures increase, simulating PV device thermal response is particularly crucial. This means that two distinct modules or cells of the same capacity under standard test conditions (STCs), which are 1000 W m−2 of AM1.56 light within a cell at 25 °C, can generate various abilities depending on the real-world environment. There is widespread agreement that PV modules frequently function at both temperatures and light levels that are above and beneath those specified by the STC.16
The interaction between poly(3-hexylthiophene-2, 5-diyl) (P3HT), a p-type donor material, and [6, 6]-phenyl-C61 butyric acid methyl ester (PCBM), an n-type acceptor material,17,18 has drawn a great deal of interest in the literature. Among conjugated polymers, poly(3-hexylthiophene) (P3HT) exhibits the greatest charge carrier mobility, with hole mobility values reaching up to 0.1 cm2 V−1 s–1.19 In addition, P3HT has a bandgap between 1.9 and 2.0 eV, which is in good agreement with the solar spectrum’s maximum,17,20 and organic molecules offer architectural flexibility.21 P3HT is a suitable option for absorbing mixes in polymer photovoltaic cells because of these advantages.22 It is well known that the addition of PCBM molecules, whether through bulk mixing23,24 or the insertion of a single layer into devices,25,26 can greatly reduce or even completely remove hysteresis. According to Wojciechowski et al.,27 a self-assembled monolayer of fullerenes at the TiO2/perovskite interface increased electron transport, which contributed to the decreased hysteresis. By adding a PCBM layer, Xing et al.28 noticed a decrease in the perovskite/TiO2 interfacial barrier. There are two common device designs used in the fabrication of high-performance PSCs. The “n-i-p,” or “regular,” structure is the first one, while the “p-i-n,” or “inverted,” structure is the second.29 In the p-i-n structure, intrinsic photoactive perovskite material is placed on the p-type Hole Transport Layer (HTL); in the n-i-p structured-type, it is deposited on top of the n-type Electron Transport Layer (ETL).30 To create low-cost and energy-efficient PSCs, experts have used device simulation and statistical analytic techniques to determine the best nip structures for PSCs using a variety of ETL and HTL layers.31 To better identify device operating parameters and improve inefficient device production and fabrication, numerical analysis or modeling is a crucial tool.32
In this device, we have used the HTL and ETL. By adopting a meso-superstructure organometal halide perovskite solar cell, it was reported by Ref. 33 in 2012 that the power conversion efficiency has increased to 10.9%. We have used a formamidinium tin iodide (FASnI3) based perovskite material. Using perovskite materials that were penetrated by a mesoporous metal oxide layer, which moves as well as gathers the ETL, such as titanium dioxide TiO2, a “regular” structure was developed between 2013 and 2014 and was topped by another layer [a hole transport material (HTM)].34 Responses to the issues with these technologies are required for further device improvement, which include the cost of spiro-MeOTAD (HTL) with silver electrodes, the less quick electron transport between the ETL and absorber, material stability, the inability to deposit the ETL on the active layer at high temperatures,35 and the price of spiro-MeOTAD (HTL) with gold electrodes.36 By guiding most charge carriers toward their destinations, these contact layers alter the short circuit current density (JSC), open circuit voltage (VOC), and overall power conversion efficiency (PCE) of the corresponding electrodes.37 Numerical analytic tools are necessary for more accurate recognition of the operating factors of the structure, and they also hold a large portion of the responsibility for the inefficiency in device manufacturing and production. Our “Solar Cell Capacitance Simulator (SCAPS)” was employed as a figurehead PSC. It computes energy band diagrams, electron/hole densities, total recombination currents, AC quantities, and functional parameters (open circuit voltage, fill factor, and power conversion efficiency). It also calculates quantum efficiency’s spectral reaction and current density vs voltage characteristics.38,39 One-dimensional optoelectrical SCAPS is employed to imitate the architectures with several semiconductor layers. Solving continuity and Poisson equations is the foundation of its operation. It is possible to build up to seven levels, and light and dark environments can be used to simulate the process. Furthermore, defect levels at interfaces and within bulk are allowed. It works with solar cells that are crystalline or amorphous.40–43
II. COMPUTATIONAL DETAILS
Our main research instrument in this work was the highly regarded simulation tool known as SCAPS (Solar Cell Capacitance Simulator), a Windows-focused application developed at the University of Gent utilizing National Instruments’ LabWindows/CVI. SCAPS is a one-dimensional modeling program for solar cell layouts in the CIGS, CuInSe2, and CdTe families.44,45 However, this software has been modified in several ways to make it more capable of operating with both crystalline solar cells (Si and GaAs family) and amorphous cells (a-Si and micromorphous Si).44 For thin film polycrystalline solar cells, the absorber/buffer interface including heterojunctions is more complicated, necessitating numerical modeling.46 SCAPS contains the greatest number of AC and DC electrical calculations, which can be done at different temperatures, in both bright and dim lighting. These measures consist of open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF %), quantum efficiency (QE %), and others.47
A. Methods
A numerical modeling tool called SCAPS is used to simulate the structural characteristics of semiconductors. The basic semiconductor equations that the model is built on are the Poisson equation and the equations for electron and hole continuity.48,49 The basic equations are as follows:
- Poisson’s equations for electrons and holes:
- Continuity equations for electrons and holes:
Au (cathode)/spiro-OMeTAD (HTL)/P3HT/FASnI3/PCBM/TiO2 (ETL)/FTO (Anode).
B. Materials
The materials used as the electron donor and acceptor were poly(3-hexylthiophene-2, 5-diyl) (P3HT) and [6, 6] phenyl C61-butyric acid methyl ester (PCBM), respectively, for the simulation of perovskite solar cells. Recombination is likely to happen when charge carriers move in the direction of the matching electrodes. Perovskite material formamidinium tin iodide (FASnI3) has been used here as an absorber layer. A crystal structure known as perovskite is characterized by a cubic arrangement of oxygen atoms that creates a framework for the placement of metallic cations, such as lead or tin. The oxygen octahedra that surround the core, usually bigger A-site cations, are surrounded by smaller B-site cations that take up the edges of the octahedra in the perovskite structure. Perovskite structure has the general chemical formula ABX3. The B atoms are smaller metal cations, such as Ti4+, and the X atoms are often oxygen. To produce electron–hole pairs within the perovskite crystal lattice, the perovskite substance must first absorb light. With the help of these pairings, sunlight may be converted into useful electrical energy, which creates an electric current. TiO2 and spiro-OMeTAD have been employed here as the ETL and HTL, respectively. In this perovskite solar cell, the Electron Transport Layer (ETL) and Hole Transport Layer (HTL) contribute important parts to enabling efficient energy flow. Together, the ETL and HTL improve the overall solar cell’s effectiveness and productivity by facilitating quick electron movement and effective hole transportation. Figure 1 shows the chemical structure of (a) FASnI3, (b) P3HT, and (c) PCBM materials, which are used in this simulation.
III. RESULTS AND DISCUSSIONS
The working process of the perovskite solar cell shown in Fig. 2 consists of several clearly defined phases. The fluorine-doped tin oxide (FTO) anode functions as a transparent conductive layer that permits light to enter the cell. The electron transport layer (ETL), which is made of titanium dioxide (TiO2), allows for effective electron transportation. The phenyl-C61-butyric acid methyl ester (PCBM) and formamidinium tin iodide (FASnI3) perovskite mixture that makes up the active layer absorbs photons and produces excitons. To get to the TiO2, photoinduced electrons pass through the PCBM/FASnI3 layer. In spiro-OMeTAD, hole transport is what moves the positive charges (holes) to the anode (FTO). Hole transport is improved by poly(3-hexylthiophene) (P3HT), which also aids in exciton dissociation. Gold (Au) serves as the cathode, capturing the electrons and completing the circuit.
A. Material parameters
Table I includes a list of the different parameters needed for simulation. It comprises the fundamental FTO, TiO2, P3HT, FASnI3, PCBM, and spiro-OMeTAD characteristics that were extracted from the published literature.
Parameters . | FTO . | TiO2 . | P3HT . | FASnI3 . | PCBM . | Spiro-OMeTAD . |
---|---|---|---|---|---|---|
Thickness(nm) | 500 | 30 | 50 | 350 | 50 | 200 |
Bandgap | 3.5 | 3.250 | 1.751 | 1.4152 | 2.0 | 2.88 |
Electron affinity | 4 | 453 | 3.5 | 3.5254 | 3.955 | 2.0556 |
Dielectric permittivity | 9 | 957 | 3.0 | 8.258 | 3.9 | 351 |
CB effective density of states (cm−3) | 2.2 × 1018 | 2.0 × 1018 | 2.0 × 102151 | 1.0 × 1018 | 2.5 × 102155 | 2.2 × 1018 |
VB effective density of states (cm−3) | 1.8 × 1019 | 1.8 × 1019 | 2.0 × 1021 | 1.0 × 1018 | 2.5 × 1021 | 1.8 × 1019 |
Electron mobility (cm2/V s) | 20 | 2050 | 1.8 × 10−3 | 2259 | 2.0 × 10−1 | 2.0 × 10−460 |
Hole mobility(cm2/V s) | 10 | 1050 | 1.8 × 10−251 | 2259 | 2.0 × 10−155 | 2.0 × 10−460 |
Shallow donor density ND (cm−3) | 2.0 × 1019 | 9.0 × 1016 | 0 | 0 | 2.93 × 1017 | 0 |
Shallow acceptor density NA (cm−3) | 0 | 0 | 1.0 × 1018 | 7.0 × 1016 | 0 | 2.0 × 1019 |
Parameters . | FTO . | TiO2 . | P3HT . | FASnI3 . | PCBM . | Spiro-OMeTAD . |
---|---|---|---|---|---|---|
Thickness(nm) | 500 | 30 | 50 | 350 | 50 | 200 |
Bandgap | 3.5 | 3.250 | 1.751 | 1.4152 | 2.0 | 2.88 |
Electron affinity | 4 | 453 | 3.5 | 3.5254 | 3.955 | 2.0556 |
Dielectric permittivity | 9 | 957 | 3.0 | 8.258 | 3.9 | 351 |
CB effective density of states (cm−3) | 2.2 × 1018 | 2.0 × 1018 | 2.0 × 102151 | 1.0 × 1018 | 2.5 × 102155 | 2.2 × 1018 |
VB effective density of states (cm−3) | 1.8 × 1019 | 1.8 × 1019 | 2.0 × 1021 | 1.0 × 1018 | 2.5 × 1021 | 1.8 × 1019 |
Electron mobility (cm2/V s) | 20 | 2050 | 1.8 × 10−3 | 2259 | 2.0 × 10−1 | 2.0 × 10−460 |
Hole mobility(cm2/V s) | 10 | 1050 | 1.8 × 10−251 | 2259 | 2.0 × 10−155 | 2.0 × 10−460 |
Shallow donor density ND (cm−3) | 2.0 × 1019 | 9.0 × 1016 | 0 | 0 | 2.93 × 1017 | 0 |
Shallow acceptor density NA (cm−3) | 0 | 0 | 1.0 × 1018 | 7.0 × 1016 | 0 | 2.0 × 1019 |
B. Current density (J–V) vs voltage characteristics
Figure 3 shows the J–V characteristics of the simulated device at dark and after illumination conditions. The graph demonstrates that there is no current density in the dark area, but following lighting, the current density changes as the voltage increases and exhibits different lines of values at various temperatures. The voltage in this instance ranges from 0 to 1.3 V. We observe five separate value lines for five different operating temperatures in the illuminated zone as the voltage and temperature increase. At operating temperatures of 200, 300, 400, 500, and 600 K, the short circuit current density (JSC) value began from −25 mA/cm2 and displayed an uninterrupted line until it reached the greatest value at voltages of 1.3 V, 1.05 V, 0.9 V, 0.7 V, and 0.5 V, respectively. It is widely understood that in the absence of light, solar cells are supposed to function as a diode. While the device illuminates, current is produced. As we can see, current density decreases as temperature and voltage increase. This is because state-dependent recombination processes continue more quickly at high temperatures, altering the density of states, which is represented by a decrease in the photovoltaic voltage at higher temperatures. Lower FF values also represent the higher recombination’s effects on increased series resistance and shorter photocarrier diffusion length.61 In low temperatures, due to reverse bias, there are lower leakage currents due to reduced thermal excitation of carriers, enhancing diode quality. However, higher leakage currents at high temperatures due to enhanced carrier generation and ion migration increase the risk of thermal breakdown and permanent damage to the cell. In summary, low temperatures improve performance and stability, while high temperatures degrade them, exacerbating reverse bias effects. “Temperature Impact on Perovskite Solar Cells under Operation”62 reports an observation of a similar process.
The solar cell’s parameters of the simulated devices at different operating temperatures are tabulated in Table II.
Temperature (K) Parameters . | 200 . | 300 . | 400 . | 500 . | 600 . |
---|---|---|---|---|---|
PCE (%) | 18.65 | 17.93 | 16.36 | 13.33 | 9.58 |
VOC (V) | 1.24 | 1.06 | 0.90 | 0.74 | 0.57 |
JSC (mA/cm2) | 24.70 | 25.12 | 25.30 | 25.36 | 25.32 |
FF (%) | 60.72 | 67.46 | 71.81 | 71.34 | 66.70 |
Temperature (K) Parameters . | 200 . | 300 . | 400 . | 500 . | 600 . |
---|---|---|---|---|---|
PCE (%) | 18.65 | 17.93 | 16.36 | 13.33 | 9.58 |
VOC (V) | 1.24 | 1.06 | 0.90 | 0.74 | 0.57 |
JSC (mA/cm2) | 24.70 | 25.12 | 25.30 | 25.36 | 25.32 |
FF (%) | 60.72 | 67.46 | 71.81 | 71.34 | 66.70 |
C. Energy band diagram of the simulated device
An illustration of the energy band diagram is shown in Fig. 4.
Effective diversion of charges and decreased recombination are demonstrated in perovskite solar cells as the valence band edge (EV) is below the electron quasi-Fermi level (Efn) and the conduction band edge (EC) is almost comparable with EFn. By lowering the energy barriers for electron transport and collection, this arrangement facilitates efficient electron extraction and improves solar efficiency. An equilibrium between electrons and holes is shown by the neutral line in perovskite solar cells, which is located in the interval of the conduction band edge (EC) and the electron quasi-Fermi level (EFn). Charge transfer is made more efficient by this balanced state, which reduces charge recombination. By acting as a reference point, the neutral line keeps charge carriers in a stable and ideal state, improving the solar cell’s overall performance. The energy band of formamidinium tin iodide (FASnI3), TiO2, and spiro-OMeTAD is 1.41, 3.2, and 2.88 eV, respectively.
D. Impact of thickness of the absorber layer on the device functionality at different temperatures
One of the most crucial factors in enhancing the solar cell’s performance is the active layer’s thickness. Aside from that, the operating temperature has a big impact on the device’s performance. Usually mounted outside, solar panels may operate in temperatures above 300 K. It has been reported that increasing the temperature increases the stress and strain on constructions, resulting in increased interfacial flaws, disorganization, and poor layer interconnectivity as a result. Figure 5 shows five temperatures with five distinct values for PCE, JSC, VOC, and FF together with a consistent range of absorber layer thickness for each parameter. PCE and JSC increase from 200 to 600 K, whereas VOC and FF decrease as the temperature increases within the specified thickness range of the absorber layer. Another instance is that all the individual lines for each parameter are reduced from their highest ideal value as the temperature increases from 200 to 600 K. Each parameter’s specific range for the absorber layer thickness is 50–500 nm. Whereas PCE achieves its greatest value at 200 K, which is 18%, it drops to 8% at 600 K. At 200 K, JSC achieves 24.25 mA/cm2, although this increases to 26 mA/cm2. However, VOC has an average value of 1.25 V at 200 K. However, as the temperature increases, all the lines exhibit a smooth, identical decline, reaching a minimum value of 0.55 V. Furthermore, FF exhibits its peak value of 85% at 300 K, but as the thickness supplied range and temperature increase, the value decreases to 67.5% at 600 K. However, it has the lowest value of 58% at 200 K. Increasing temperature also affects the carrier concentration, as well as the hole and electron mobilities, which lowers the PSCs’ efficiency. Due to the narrowing of the energy bandgap and the increased creation of electron–hole pairs, we also see that JSC slightly increases with temperature. The decrease in VOC can be explained by an increase in series resistance, a reduction in carrier diffusion length, and the creation of additional interfacial defects as an effect of operating temperature. The absorber layer thickness in perovskite solar cells affects the functionality by balancing light absorption and carrier transport. Thicker layers enhance light absorption but can increase recombination and ion migration at high temperatures, reducing efficiency. At low temperatures, thinner layers improve carrier extraction and reduce recombination, enhancing performance and stability.63
E. Effect of doping concentration of the absorber layer on the device’s performance at different temperatures
The concentration of absorber layer doping has little effect on the performance of perovskite solar cells at distinct temperatures. The apparatus remains stable, albeit with minor variations in its effectiveness. This indicates that doping concentration has a minimal effect on performance under temperature swings within a particular range, demonstrating the adaptability of perovskite solar cells to a variety of environments. The basic parameter fluctuations within the variation of temperatures of 200–600 K are depicted in Fig. 6. According to the graph, all the photovoltaic parameters vary significantly because of temperature variations. At 500 K, the temperature fill factor increases to 50%, and all other temperatures display nearly uniform values. Because solar cells are extremely sensitive to temperature, maintaining a high operating temperature is essential to maximizing their effectiveness. When a solar cell functions at high temperatures, it alters the properties of the solar energy components and device, including carrier concentrations, absorbance coefficients, bandgaps, effective density of states, and electron and hole mobility.64 The doping concentration in the absorber layer of a perovskite solar cell significantly impacts its performance across different temperatures. At low temperatures (200 K), optimal doping enhances carrier concentration and mobility, reducing trap-assisted recombination and increasing open-circuit voltage (VOC) and efficiency. Conversely, under-doping limits the carrier density, leading to higher series resistance and lower efficiency. At high temperatures (up to 600 K), excessive doping increases ion migration and thermal excitation of carriers, creating more defect states and non-radiative recombination centers, which degrade VOC and the fill factor, reducing overall efficiency. However, optimal doping balances carrier concentration and thermal stability, mitigating some performance losses by reducing defect state formation. In summary, the doping concentration must be carefully optimized to balance carrier transport and recombination rates, particularly considering temperature-dependent effects on device stability and efficiency. Some almost similar observations with slightly different operations are shown in “Investigating the performances of cadmium telluride solar cells using doping concentrations, carrier lifetimes, the thickness of layers, and bandgaps.”64
F. Effect of electron affinity of the electron transport layer on the device parameters’ operation at various temperatures
The device’s performance at all temperatures is greatly influenced by the electron affinity of the electron transport layer. Charge mobility is affected by changed electron affinities, which also affect conductivity and energy level alignment. The device parameters, including current–voltage characteristics and overall operational efficiency, are directly shaped by this temperature-dependent modulation of electron affinity. These parameters are essential for customized functionality in a variety of thermal settings.65 In Fig. 7, the fill factor abruptly decreased to 200 K at first, then began to increase, and finally produced a uniform line. In addition, other parameters increased from their lower values to the uniform range. Every parameter increases with temperature; after 400 K, from 500 to 600 K, every parameter began to display a constant value. Similar observations have been made in Refs. 66 and 67. The electron transport layer’s electron affinity governs the energetic alignment at the interface, impacting charge extraction efficiency and recombination rates. A higher affinity fosters efficient electron transfer, diminishing recombination losses, which is crucial for maintaining device performance parameters such as fill factor and open-circuit voltage across varying temperatures.
G. Effect of electron affinity of the hole transport layer on the device parameters’ operation at various temperatures
The electron affinity of the hole transport layer profoundly shapes the operational characteristics of the device, especially in the context of temperature variations. At elevated temperatures, changes in the electron affinity influence the device’s internal charge transport efficiency. This influence is crucial for applications where temperature fluctuations are common, such as in electronic systems subject to varying environmental conditions. Studying the nuanced relationship between electron affinity and temperature-specific operational parameters is essential for tailoring device designs that maintain optimal performance and stability across a spectrum of temperatures, ensuring reliability and functionality in real-world applications. Blocking electrons by gathering holes off the layer of absorption and transferring toward a particular way of the cathode is the job of the HTL. Any material must have its lowest unoccupied molecular orbital (LUMO) slightly lower and its highest occupied molecular orbital (HOMO) just elevated relative to the perovskite absorber layer to operate as a suitable hole transport layer (HTL). Its hole mobility should be greater than 103 cm2 V–1 s−1, ideally, so that recombination is minimized and holes are transmitted effectively. For the device to obtain a high-voltage open circuit, it must facilitate the splitting of quasi-Fermi levels of the perovskite.68 From Fig. 8, it can be seen that as the temperature increases, the parameters begin to exhibit a consistent value at 200 K and begin to decline as electron affinity increases. This pattern continues until 600 K. Charge carrier dynamics in perovskite solar cells are directly influenced by the hole transport layer’s electron affinity. A greater electron affinity reduces trap-assisted recombination and makes hole extraction more effective; this is especially important at high temperatures where carrier mobility is increased. On the other hand, under heat stress, in particular, a decreased electron affinity aggravates recombination pathways and degrades device performance. The following periodicals have explored similar observations: Detailed device modeling of a perovskite solar cell using inorganic copper iodide as the material for hole transport.69
H. The result of the electron transport layer’s thickness on the device’s operating aspects at different temperatures
The precise thickness of the electron transport layer emerges as a critical factor shaping the operational characteristics of electronic devices, particularly when subjected to different temperatures. The electron transport layer (ETL) thickness profoundly influences the device’s operation across temperatures. Optimal thickness balances charge transport and recombination. Thicker ETLs enhance transport but increase recombination losses, impairing efficiency at higher temperatures due to increased carrier diffusion lengths and Auger recombination. Thinner ETLs mitigate recombination but can impede charge extraction, particularly at lower temperatures due to reduced carrier mobility and increased interface recombination. Thus, ETL thickness critically modulates device performance under varying thermal conditions. Figure 9 illustrates the lack of effect of thickness on the parameters PCE, VOC, JSC, and FF. At 200 K, the parameter exhibits its lowest value; nevertheless, when the temperature increases, all the parameters exhibit a consistent increase from their original value to 600 K. On top of the n-type ETL, the n-i-p material used is a structured-type intrinsic photoactive perovskite. To ascertain this, researchers have utilized numerical analysis methods and device modeling optimal n-i-p structures for PSCs employing various ETLs.70 The electron transport layer has minimal impact on perovskite solar cell electrical parameters. The perovskite material generates charge carriers, and even without the ETL, the transparent conducting oxide serves as an effective charge transport layer. Adding an optimal ETL layer can enhance the fill factor.71,72 Similar observations have been obtained in Ref. 73.
I. The impact of the hole transport layer’s thickness on the device’s performance parameters at various temperatures
The thickness of the hole transport layer profoundly shapes the performance of electronic devices across temperature variations. Thicker layers can enhance charge transport efficiency at lower temperatures but might impede it at higher temperatures. Conversely, excessively thin layers may compromise conductivity. Achieving an optimal thickness balance is crucial for maximizing device performance across diverse thermal conditions. The interplay between layer thickness and temperature intricacies underscores the nuanced engineering required to fine-tune electronic devices for consistent operation under varying thermal environments. Controlling the hole transport layer’s thickness emerges as a critical factor in tailoring devices for optimal performance across a spectrum of temperatures. Figure 10 illustrates how the open circuit voltage (VOC) shows a uniform value as the thickness of the hole transport layer increases between 200 and 600 K. In contrast, other parameters such as JSC, PCE, and FF decrease from their upper values to a uniform line as the temperature and thickness increase and PCE decreases. Elevated temperature leads to elevated stress and deformation, which in turn produces a greater number of interfacial defects and heightened SRH recombination.74 As a result, PCE and FF are reduced when the diffusion length decreases and series resistance increases.75 The decrease in JSC may result from a negative temperature coefficient for JSC, which is relevant to perovskite solar cells, and an expanded bandgap with increasing temperatures.76,77 Once more, as the temperature increases, J0 increases and VOC decreases. The hole transport layer (HTL) thickness in perovskite solar cells affects temperature-dependent characteristics, interface recombination, light absorption, contact resistance, and charge transport in addition to recombination rates. HTL thickness can be tailored to improve light absorption, minimize recombination, optimize charge collection, lower contact resistance, and adapt device performance to different temperatures. Some similar observations have been observed in Ref. 66.
IV. QUANTUM EFFICIENCY
Internal quantum efficiency (IQE) and external quantum efficiency (EQE, often referred to as classical efficiency) are used to measure a solar cell’s efficiency. The solar cell’s optical performance and the proportion of charge production to photons of incoming light are considered by the EQE. Conversely, the IQE measures the ratio of electrons gathered by photocurrents to the total amount of photons absorbed at a given wavelength. With the use of IQE, it will be possible to anticipate each of the total current production below the solar spectrum and the region of the solar spectrum that the active substances employ to generate electricity.78,79 In contrast, a more thorough examination of the traditional efficiency, or EQE, may be conducted in the future. The study examined the impact of varying light irradiation wavelengths, within 300 and 900 nm, on the perovskite active layer’s effectiveness. The wavelength portion that is transformed into an electron–hole pair and extracted as a charge carrier from the active material is known as the IQE.80 Figure 11 demonstrates that quantum efficiency improves with wavelength, first increasing from 300 nm to more than 350 nm at standard operating temperature (300 K). However, the QE begins to decrease after 400 nm, and over a long range of nearly 900 nm, it produces a uniform line. A study follows reports on similar operations.81
V. DEVICE’S HYSTERESIS INDEX
The hysteresis index of the simulated device at standard operating temperature (300 K) is listed in Table III.
Parameters . | Normal . | Inverted . |
---|---|---|
PCE (%) | ⋯ | 0 |
JSC (mA/cm2) | ⋯ | 0 |
VOC (V) | ⋯ | −0.5031 |
Parameters . | Normal . | Inverted . |
---|---|---|
PCE (%) | ⋯ | 0 |
JSC (mA/cm2) | ⋯ | 0 |
VOC (V) | ⋯ | −0.5031 |
Figure 12 demonstrates the hysteresis index for the dark and light regions. In perovskite solar cells, hysteresis zero denotes very little voltage variation during forward and reverse scans, which improves stability. Normal hysteresis displays an increase; however, inverted hysteresis suggests a reverse scan voltage drop. Improved performance is indicated by lower numbers; zero is the best value for stability in solar cell applications. In a perovskite solar cell, the short-circuit current (JSC) and power conversion efficiency (PCE) hysteresis indices are zero, indicating exceptional stability. A zero-hysteresis index indicates very little voltage fluctuation over scans, indicating a dependable and steady performance in the conversion of solar radiation into electrical power. While a perovskite solar cell’s fill factor (FF) stays normal and the open-circuit voltage (VOC) hysteresis index is inverted, it suggests a reversible voltage decrease during scanning but constant efficiency in converting sunlight into energy. This combination points to possible stability gains that would not sacrifice the overall performance. The graphical depiction of HI is provided.
The research article “Defect states influencing hysteresis and performance of perovskite solar cells”91 examined similar observations.
VI. PARASITIC LOSSES ON CELL PERFORMANCE
In perovskite solar cells, the transparent conductive oxide (TCO) layer, charge transport layers, and device interfaces are the primary sources of parasitic resistance losses, which manifest as series resistance. These resistive elements obstruct the flow of electrons and holes, which lowers the total electrical conductivity and, consequently, the solar cell’s efficiency. The series resistance (Rs) in photovoltaic (PV) modules includes resistances within cell solder bonds, emitters, base regions, metallization, interconnect busbars, and junction-box terminations. Despite efforts to minimize these losses, daily outdoor thermal cycling incrementally increases the series resistance, as illustrated in Fig. 13. The heightened Rs results in reduced module voltage output, diminished fill factor, and compromised performance quality. These effects adversely impact characteristics such as short-circuit current (JSC).92 The numerical findings by increasing series resistances and decreasing shunt resistances are tabulated in Tables IV and V, respectively.
RS (Ω) . | PCE (%) . | JSC (mA/cm2) . | VOC (V) . | FF (%) . | Loss (%) in PCE (%) . | Loss (%) in FF (%) . |
---|---|---|---|---|---|---|
0.50 | 17.38 | 24.985 | 2.2278 | 31.23 | 25 | 42 |
1.50 | 16.90 | 24.956 | 2.2278 | 30.39 | 73 | 126 |
2.50 | 16.41 | 24.927 | 2.2278 | 29.55 | 122 | 210 |
RS (Ω) . | PCE (%) . | JSC (mA/cm2) . | VOC (V) . | FF (%) . | Loss (%) in PCE (%) . | Loss (%) in FF (%) . |
---|---|---|---|---|---|---|
0.50 | 17.38 | 24.985 | 2.2278 | 31.23 | 25 | 42 |
1.50 | 16.90 | 24.956 | 2.2278 | 30.39 | 73 | 126 |
2.50 | 16.41 | 24.927 | 2.2278 | 29.55 | 122 | 210 |
RSH (Ω) . | PCE (%) . | JSC (mA/cm2) . | VOC (V) . | FF (%) . | Loss (%) in PCE (%) . | Loss (%) in FF (%) . |
---|---|---|---|---|---|---|
500 | 16.35 | 24.99 | 1.9722 | 33.15 | 128 | −150 |
250 | 15.07 | 24.99 | 1.7692 | 34.06 | 256 | −295 |
100 | 11.42 | 24.99 | 1.3518 | 33.79 | 621 | −214 |
RSH (Ω) . | PCE (%) . | JSC (mA/cm2) . | VOC (V) . | FF (%) . | Loss (%) in PCE (%) . | Loss (%) in FF (%) . |
---|---|---|---|---|---|---|
500 | 16.35 | 24.99 | 1.9722 | 33.15 | 128 | −150 |
250 | 15.07 | 24.99 | 1.7692 | 34.06 | 256 | −295 |
100 | 11.42 | 24.99 | 1.3518 | 33.79 | 621 | −214 |
In this case, the series resistance has been observed within 0.50, 1.5, and 2.5 Ω whereas when the resistance increases, the PCE and FF decrease and JSC slightly decreases. An increase in parasitic series resistance in solar cells leads to decreased power conversion efficiency (PCE), fill factor (FF), and short-circuit current (JSC), as it impedes efficient charge transport. However, if the open-circuit voltage (VOC) remains constant, it suggests that the intrinsic electronic properties of the cell are not affected by the resistive losses.
Again, a reduction in shunt resistance within parasitic elements leads to decreased power conversion efficiency (PCE) and open-circuit voltage (VOC) in perovskite solar cells. Despite a constant short-circuit current (JSC), fill factor (FF) fluctuations suggest variations in charge carrier recombination, influencing voltage output and overall cell performance dynamics.
Low resistance to cell shunting is harmful. In thin-film cells and modules, especially after extended light exposure, shunt resistance values may decrease because of additional shunt routes across the p–n junction.93,94 A graphical representation of parasitic loss of series resistance and shunt resistance is given in Fig. 13.
VII. CONCLUSION
In this study, numerical analysis of n-i-p solar cells using FASnI3 perovskite material is performed using SCAPS simulation software. This research focused on assessing the temperature variation’s interactions with device functionality. A notable finding was the inverse relationship between temperature and power conversion efficiency (PCE). The obtained PCE of 9.58% was below the typical efficiency, highlighting the adverse effects of increased temperatures. We have found that the short-circuit current density and power conversion efficiency of the simulated n-i-p perovskite solar cell increase in response to the increase in the thickness of the FASnI3 layer. Our results show that at a lower operating temperature, the doping concentration of the absorber layer does not affect the performance of the device, but the device efficiency decreases at a higher operating temperature (600 K). Another important parameter of the n-i-p structured solar cell is the electron affinity of the ETL and HTL. This simulation study validated that the variation in electron affinity of the ETL and HTL has no significant effect on device PCE at 200, 300, 400, and 500 K operating temperatures. The PCE is decreased by the device when it operates at 600 K temperature. The ETL’s variation in thickness has shown a similar outcome. However, the variation in thickness of the HTL obeys the same profile at operating temperatures of 200, 300, and 400 K. Approximately, a similar profile has been observed at operating temperatures of 500 and 600 K. We conclude that our simulated perovskite solar cell works fine at low temperatures, and as the temperature increases, its efficiency decreases. Our work highlights the opportunity to improve the performance or efficiency of n-i-p based FASnI3 perovskite solar cells in the face of temperature fluctuations and presents viable options for the generation of sustainable energy in the field of perovskite solar technology.
ACKNOWLEDGMENTS
The authors thank the MBSTU Research Cell, Mawlana Bhashani Science and Technology University, Santosh, Tangail, Bangladesh, for the research grant and are grateful to Professor Marc Burgelman for the SCAPS-1D simulation software.
AUTHOR DECLARATIONS
Conflict of Interest
The authors have no conflicts to disclose.
Author Contributions
Poroma Afrin: Data curation (equal); Formal analysis (equal); Methodology (equal); Writing – original draft (equal). Kanize Farjana: Data curation (supporting); Formal analysis (supporting); Investigation (supporting); Writing – review & editing (supporting). Anjon Vumije: Data curation (supporting); Formal analysis (supporting); Investigation (supporting); Writing – review & editing (supporting). Md. Nasir Uddin: Conceptualization (lead); Data curation (equal); Funding acquisition (lead); Project administration (lead); Resources (lead); Supervision (lead); Validation (lead); Visualization (lead); Writing – review & editing (equal).
DATA AVAILABILITY
The data that support the findings of this study are available within the article.