Performance Of Solar Cells Research Articles

Thermal and optical analysis of industrial photovoltaic modules under partial shading in diverse environmental conditions

The manuscript offers a fresh perspective on understanding the impact of shading on the overall performance of solar cells. While the term “hot spot” is commonly used to describe a location where a cell or module can experience significant damage, this study devotes attention to several comprehensive analyses that could prove valuable for module performance, considering the impacts ofshading, UV radiation, and thermal. This article explores the relationship between spot shading and percentage shadings and their effects on module layers’ internal temperature, stress, and deformation. The findings reveal that shading within 50–70% (precisely around 62.5% for this study) increases maximum module temperature, stress, and deformation. Additionally, spot shading has a more pronounced effect on the corner positions of the PV module. Including electrical measurements such as open circuit voltage, short circuit current and maximum power provides valuable insights. This work also highlights the limiting of PV module performance due to ultraviolet (UV) radiation, with even greater acceleration observed in partially damaged cells.

Construction of ultra-smooth and void-free buried interface via bilateral chemical bridging for efficient and hysteresis-suppressed perovskite solar cells

The surface properties are vital aspects in improving photovoltaic performance of perovskite solar cells (PSCs). Except for the upper surface of perovskite, the hidden buried interface which supports the beginning of perovskite film crystallization is of equal great importance for the construction of high-efficiency PSCs. Herein, we use urea phosphate (UPP) to build a bilateral chemical bridge in the buried interface under perovskite layer, to simultaneously improve the properties of SnO2 ETL and the upper perovskite. On one hand, the interaction between UPP and SnO2 passivates the defects of the SnO2 and facilitates the formation of ultra-smooth surface for superior interfacial contact. On the other hand, the chemical interaction between UPP and perovskite contributes to the optimization of crystal nucleation and growth, which improves the crystalline quality of perovskite, inhibits the formation of voids at the buried interface and reduces the defects of the grain boundary. Benefiting from the optimized buried interfacial contact, suppressed defects, accelerated charge extraction and modified energy level alignment, the UPP-processed device delivers an improved power conversion efficiency of 24.54 %, with effective suppression of hysteresis. Moreover, the stability of device is also improved owing to the reduction of trap defects. This work provides a feasible strategy to tune the buried interface between the charge transfer layer and perovskite layer for fabrication of efficient and stable PSCs.

Effect of Iron Contamination and Polysilicon Gettering on the Performance of Polysilicon‐Based Passivating Contact Solar Cells

ABSTRACTOver the past decade, silicon solar cells with carrier‐selective passivating contacts based on polysilicon capping an ultra‐thin silicon oxide (commonly known as TOPCon or POLO) have demonstrated promising efficiency potentials and are regarded as an evolutionary upgrade to the PERC (passivated emitter and rear contact) cells in manufacturing. The polysilicon‐based passivating contacts also exhibit excellent gettering effects that relax the wafer and cleanroom requirements to some extent. In this work, we experimentally explore the impact of bulk iron contamination and polysilicon gettering on the passivation quality of the polysilicon/oxide structure and the resulting solar cells performance. Results show that both n‐ and p‐type polysilicon/oxide passivating contacts are not affected by iron gettering, demonstrating robust and stable passivation quality. However, for a very high bulk iron contamination (1 × 1013 cm−3), the accumulated iron in the p‐type lightly boron‐doped emitter in crystalline silicon would degrade the emitter saturation current density. This can cause a reduction in both open‐circuit voltage and short‐circuit current. Meanwhile, this very high iron content (1 × 1013 cm−3) can further degrade the fill factor and temperature coefficient of the cells. On the other hand, for an initial iron content of 2 × 1012 cm−3, which should be well above the iron level in the current industrial Czochralski silicon wafers, the resulting cells demonstrate similar performance as the control group with no intentional iron contamination. This work brings attention to both the benefits of polysilicon gettering effects as well as the potential degradation due to the accumulation of metal impurities in the p‐type emitter region.

A computational analysis to enhance performance of CIGS solar cells using back surface field and ZnSe buffer layer approach

Abstract This study aims to enhance CIGS solar cell efficiency while minimizing environmental impact by replacing the toxic CdS buffer layer with a ZnSe buffer layer. The CIGS chalcogenide semiconductor is a promising solar cell absorber material but has faced challenges related to defect-free manufacturing, misaligned buffer layers, and device configuration. Cuprous oxide (Cu2O) and zinc selenide (ZnSe), an inexpensive, eco-friendly, and widely available material, are suggested as a back surface field layer and buffer layer to enhance device performance. This paper proposes a new cadmium-free structure (Al/ZnO: Al/ZnO/ZnSe/CIGS/Cu2O/Ni) to enhance the efficiency of CIGS heterojunction solar cells by reducing charge carrier recombination losses. We utilized SCAPS-1D to simulate photovoltaic (PV) performance and examined the impacts of electron affinity, absorber thickness, interface defect density, operating temperature, radiative recombination coefficient, Mott-Schottky analysis, parasitic resistance, and quantum efficiency on photovoltaic characteristics. Optimization and choosing a suitable buffer and passivation layer gives the device efficiency of 31.13%, followed by VOC (0.92 V), JSC (40.40 mA/cm2), and FF (83.34 %) for the proposed structure. The radiative recombination coefficient found to be 10-13 cm3/s and the parasitic resistance of the solar cell are in good agreement for fabricating high-efficiency solar cells. These findings suggest that CIGS-based heterojunction solar cells represent a cutting-edge method for achieving high-efficiency solar cells that outperform earlier designs.

T-Shaped-N-Doped Polycyclic Aromatic Hydrocarbons: A New Concept of Dopant-Free Organic Hole-Transporting Materials for Perovskite Solar Cells.

Although metal halide perovskites are positioned as the most powerful light-harvesting materials for sustainable energy conversion, there is a need for a thorough understanding of molecular design principles that would guide better engineering of organic hole-transporting materials, which are vital for boosting the performance and stability of perovskite solar cells. To address this formidable challenge, here, we developed a new design strategy based on the curved N-doped polycyclic aromatic hydrocarbon merged with T-shaped phenazines being decorated with (phenyl)-di-p-methoxyphenylamine (OMeTAD)─N-PAH23/24 and -3,6-ditertbutyl carbazole (TBCz)─N-PAH25/26. As N-PAH23/24 exhibited satisfying thermal stability, the comparative studies performed with various experimental and simulation methods revealed a pronounced correlation between the depth of the central cyclazine core and the form of the T-shape units. This proved to be a crucial factor in controlling their π-π intermolecular interaction as well as self-assembly behavior with the perovskite layer, leading to enhanced humidity resistance, operational stability, and a maximum power conversion efficiency of 20.39% denoted for N-PAH23, which is superior to the benchmarked device with doped spiro-OMeTAD (19.23%). These studies not only resulted in optimized stability and device performance but also opened a conceptually new chemical space in the photovoltaic technology.

Visualization of Anion Vacancy Defect Annihilation in CZTSe Solar Cells by Hydrogen-Assisted Selenization with In Operando X-ray Nanoprobe Studies.

The traditional sulfur selenization process in Cu2ZnSn(S,Se)4 (CZTSSe) solar cell fabrication often results in the creation of localized anion vacancies (VS and VSe). These vacancies are considered harmful defects as they can trap carriers generated by light, leading to reduced solar cell efficiency. Moreover, concrete evidence has been lacking on the extent of the impact caused by these anion vacancies. Our research introduces a novel approach: the hydrogen-assisted selenization (HAS) process, specifically designed to minimize localized anion vacancies in Cu2ZnSnSe4 (CZTSe) solar cells. Our investigation, utilizing current-voltage (I-V) and admittance spectroscopy measurements, provides clear insights. We observed notable improvements in carrier collection efficiency and a discernible reduction in defect states. Furthermore, there was a significant decrease in the activation energy required within the solar cell device, dropping from 184 to 145 meV. To delve deeper into the structural and compositional aspects, we employed synchrotron-based X-ray nanoprobes. Through nanoscale X-ray fluorescence and hard X-ray beam-induced current measurements, we can directly observe and document the relationship between the local compositional distribution and photocurrent activity in operando. These comprehensive results furnish strong evidence that mitigating anion vacancies in the CZTSe layer can substantially improve the power conversion efficiency of the CZTSe solar cells. This advancement not only sheds light on the critical role of anion vacancies in solar cell performance but also underscores the effectiveness of the HAS process in enhancing overall device efficiency.

Fullerene-Hybridized Fused-Ring Electron Acceptor with High Dielectric Constant and Isotropic Charge Transport for Organic Solar Cells.

A novel isotropic fullerene-hybridized fused-ring electron acceptor, designated C60-Y, has been synthesized via a mild [4+2] Diels-Alder cycloaddition reaction with fullerene C60 to enhance the performance of organic solar cells (OSCs). Comparative analysis shows that C60-Y significantly outperforms the control acceptor Me-Y, with a notable increase in the relative dielectric constant from 2.79 to 3.95. This improvement enhances exciton dissociation and reduces non-radiative energy losses. Additionally, the isotropic molecular packing of C60-Y, similar to fullerene, facilitates efficient interface formation with donor polymers and improves charge mobility. As a result, incorporating C60-Y as an electron acceptor increases the power conversion efficiency (PCE) of binary OSCs to 15.02 %, surpassing the 13.31 % achieved with Me-Y. Moreover, when integrated into a ternary blend system, an impressive PCE of 19.22 % is achieved, top-performing among reported ternary OSCs utilizing fullerene derivatives as the third component. These results suggest that fullerene-hybridized acceptors like C60-Y hold great potential for advancing high-efficiency OSCs by enhancing exciton dissociation, reducing energy losses, and improving charge mobility.

The effect of the introduction of internal acceptor and the variation of π-spacer groups in carbazole-based organic dyes on the photovoltaic performance of dye-sensitized solar cells: a DFT study

The effect of the introduction of internal acceptor and the variation of π-spacer groups in carbazole-based organic dyes on the photovoltaic performance of dye-sensitized solar cells: a DFT study

Photovoltaic Efficiency Enhancement of Indium-Free Wide-Bandgap Chalcopyrite Solar Cells via an Aluminum-Induced Back-Surface Field Effect.

Wide-bandgap chalcopyrite materials are attractive candidates for a wide variety of energy conversion devices such as the top cell of tandem-type photovoltaic devices and photoelectrochemical water splitting hydrogen evolution devices. Nevertheless, simultaneous realization of high open circuit voltage (VOC) and high fill factor (FF) values has been challenging, and thus, the photovoltaic performance has been limited. In this article, high VOC and high FF values of wide-gap chalcopyrite CuGaSe2 thin-film solar cells are simultaneously demonstrated using an aluminum-induced back-surface field effect. An independently certified photovoltaic efficiency of 12.25% was obtained from an elemental In-free CuGaSe2:Al (bandgap energy ∼1.7 eV) solar cell (VOC: 0.959 V, short circuit current density: 17.64 mA cm-2, FF: 72.5%). In addition, an over 1 V-VOC CuGaSe2 cell (FF: 74.5%) was obtained even with the use of a conventional CdS buffer layer. Although incorporation of aluminum often leads to degradation of the chalcopyrite solar cell performance, the addition of a small amount of aluminum is found to be effective in enhancing wide-gap chalcopyrite photovoltaic performance.

Thickness and Doping Density Influence of a High-Voltage Inorganic Perovskite Solar Cell: A SCAPS 1-D Simulation Study

Recently, all inorganic perovskite solar cells have triggered great attention thanks to the rising performance during their development in solid state photovoltaics showing enhanced characteristics, such as: good stability, high photoluminescence quantum yield, tunable size, and morphology. In this work, a high open-circuit voltage solar cell based on all-inorganic perovskite through SCAPS simulator program is presented by analysing electron transport layer (ETL), perovskite layer, hole transport layer (HTL) thickness and doping density from a FTO/TiO2/CsPbBr3/Spiro-OMeTAD/Au structure were modified to observe its influence on solar cell performance. Therefore, simulation results show that a thicker ETL hinders carrier transport towards the FTO layer due to larger distance which leads to higher recombination rate, reducing carrier’s lifetime. Albeit high doping density values in ETL enhances the overall solar cell performance. As for the absorber layer, while its thickness increases, carrier collection rate decreases due to recombination impacting Voc, which results from thickness increase. Based on the results, solar cell efficiency improvement is attributed to the built-in electric field as absorber layer doping density increases. While HTL thickness has minimum impact on the solar cell output, doping density enhances device parameters significantly. Summarising the results obtained from thickness and doping density simulations, the optimal solar cell operation was obtained at 10 nm, 600 nm, and 100 nm layer thickness as well as 1020 cm-3, 1016 cm-3, and 1020 cm-3 doping density (TiO2, CsPbBr3 and Spiro-OMeTAD). Results from three different sources, collected from literature, were used to compare, and fitting them along with simulation results.

Interfacial Proton Precompensation: Suppressing Deprotonation-Driven Lattice Collapse for Enhanced Efficiency and Stability in Perovskite Solar Cells.

The chemical property of the buried interface plays a crucial role in improving the performance and stability of perovskite solar cells (PSCs). The SnO2/perovskite interface prepared from SnO2 alkaline hydrogel with high proton affinity triggers directional migration and irreversible reactions of protons, exacerbating the disintegration of perovskite crystal. In this study, we proposed proton precompensation strategy to suppress the deprotonation effect of the buried interface and improve the durability of the devices. By modulating the chemical environment and surface energy state of the buried interface, the domain-limiting and spontaneous compensation of protons in formamidinium (FA+) under Coulomb force were achieved, thereby stabilizing the perovskite crystal structure. The stability of target perovskite films under UV illumination and heating at 85 °C was significantly enhanced. As a result, the devices can retain around 90% of their initial power conversion efficiency (PCE) after 1000 h of continuous irradiation at the maximum power point (MPP). Moreover, due to the reduction of defect content at the buried interface and the improvement of conductivity and carrier mobility by the precompensation treatment, the interfacial energy loss and non-radiative recombination were substantially diminished. The target PSC devices exhibited much higher PCE of 25.55% than the control devices (23.03%).

Perspective of environmentally friendly antimony selenide-based solar cell

Antimony selenide has been intensively investigated as an interesting alternative for solar cell absorbers due to its excellent physical properties. Owing to the remarkable advancements in the last several decades, chemical and physics methods have improved the power conversion efficiency of antimony selenide solar cells by over 10%, almost at the level needed for industrial applications. In this perspective, we have outlined the issues and challenges these antimony chalcogenides face in photoelectric applications. We have proposed some feasible suggestions for improving its performance and applications in solar cells and other optoelectronic devices.

Interfacial Proton Precompensation: Suppressing Deprotonation‐Driven Lattice Collapse for Enhanced Efficiency and Stability in Perovskite Solar Cells

The chemical property of the buried interface plays a crucial role in improving the performance and stability of perovskite solar cells (PSCs). The SnO2/perovskite interface prepared from SnO2 alkaline hydrogel with high proton affinity triggers directional migration and irreversible reactions of protons, exacerbating the disintegration of perovskite crystal. In this study, we proposed proton precompensation strategy to suppress the deprotonation effect of the buried interface and improve the durability of the devices. By modulating the chemical environment and surface energy state of the buried interface, the domain‐limiting and spontaneous compensation of protons in formamidinium (FA+) under Coulomb force were achieved, thereby stabilizing the perovskite crystal structure. The stability of target perovskite films under UV illumination and heating at 85 °C was significantly enhanced. As a result, the devices can retain around 90% of their initial power conversion efficiency (PCE) after 1000 h of continuous irradiation at the maximum power point (MPP). Moreover, due to the reduction of defect content at the buried interface and the improvement of conductivity and carrier mobility by the precompensation treatment, the interfacial energy loss and non‐radiative recombination were substantially diminished. The target PSC devices exhibited much higher PCE of 25.55% than the control devices (23.03%).

Improving the Efficiency of Semitransparent Perovskite Solar Cell Using Down-Conversion Coating.

Perovskite solar cells (PSCs) have demonstrated exceptional efficiency, yet surpassing theoretical performance limits requires innovative methodologies. Among these, down-conversion techniques are pivotal in reducing optical losses and enhancing energy conversion efficiency. In this study, optical modeling, including a generalized transfer-matrix optical model, was employed to meticulously assess optical losses in semitransparent PSCs illuminated from the front and rear sides of the device. To reduce these losses, two down-conversion layers, made of N,N-diphenyl-4-(1,2,2-triphenylethenyl)-benzenamine and 4-(N,N-diphenylamino)benzaldehyde mixed with polymeric binder, were developed, showcasing initial photoluminescence quantum yields of 60% and 50% as films, respectively. The materials luminescence relies on the effect of aggregation-induced emission, which enhances the fluorescence of the dyes within the binder, providing their films with a unique behavior beneficial for photovoltaic applications. An optimization of these layers was performed, which aimed to reduce UV optical losses by adjusting the film thickness atop the PSCs. The refined down-conversion layers yielded a notable increase in the power conversion efficiency by approximately 0.4% for both the front and rear sides of the PSCs, demonstrating their significant potential in pushing the boundaries of solar cell performance.

Micro-homogeneity of lateral energy landscapes governs the performance in perovskite solar cells

Suppression of energy disorders in the vertical direction of a photovoltaic device, along which charge carriers are forced to travel, has been extensively studied to reduce unproductive charge recombination and thus achieve high-efficiency perovskite solar cells. In contrast, energy disorders in the lateral direction of the junction for large-area modules are largely overlooked. Herein, we show that the micro-inhomogeneity characteristics in the surface lateral energetics of formamidinium (FA)-based perovskite films also significantly influence the device performance, particularly with accounting for the stability and scale-up aspects of the devices. By using organic amidinium passivators, instead of the most commonly used organic ammonium ones, the micro-inhomogeneity in the lateral energy landscapes can be suppressed, greatly improving device stability and efficiency of FA-based single-junction perovskite solar cells.

Preparation and Growth Mechanism of Pyramid‐Shaped Cu2ZnSnS4 Monocrystal and the Simulation of Its Monograin Layer Solar Cells

AbstractThe Cu2ZnSnS4(CZTS) monocrystal as an important component of the optical absorption layer in monograin layer solar cells, has excellent crystallization characteristics and adjustable photogenerated carrier concentration. The shape of the CZTS monocrystal directly affects the utilization of incident light and the contact area during the preparation of the back electrode when they are densely packed to form a single‐layer absorption layer. Herein, a kesterite‐phase pyramid‐shaped CZTS monocrystal prepared by the molten salt method is reported, which can improve the efficiency of incident light utilization and increase the contact area during back electrode preparation. The X‐Ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy are used to characterize the crystallinity and crystal shape of pyramid‐shaped CZTS monocrystal. Besides, Finite‐Difference simulation calculation is employed to reveal the optical response and corresponding monograin layer solar cells performance of densely packed CZTS. The results show that the pyramid‐shaped structure exhibited excellent incident light trapping ability, and the simulated device achieves a cell efficiency with above 13.6% after parameter optimization. The work provides a method for preparing pyramid‐shaped CZTS monocrystal, and a new strategy to further improve the efficiency of CZTS‐based monograin layer solar cells.

Enhanced performance of Mg and La co-doped TiO2(98%)−ZrO2(2%) photoanode for dye-sensitized solar cells

Abstract This study explores the effects of magnesium (Mg) and lanthanum (La) doping on the performance of dye-sensitized solar cells (DSSCs) utilizing TiO2(98%)−ZrO2(2%) (TZ, TZM, and TZL) photoanodes. The photoanodes were fabricated using a spin-coating sol–gel method, followed by calcination at 400°C. The structural, morphological, crystallographic, and optical properties of the proposed photoanode composites were characterized by X-ray diffraction, transmission electron microscopy, and ultraviolet–visible spectroscopy. The crystallite sizes of the synthesized thin films varied from 21.16 to 59.04 nm for the TZ, TZM, and TZL compositions. The current–voltage measurements of DSSCs based on TZL8 photoanode, cobalt sulfide-doped graphene counter electrode, and N719 dye revealed the highest efficiency of nearly 5.052%. The assembled DSSCs exhibited an open-circuit voltage of 0.74 V, a short-circuit current density of 9.964 mA/cm2, and a fill factor of 0.685. The enhancement in open-circuit voltage and short-circuit current density could be attributed to the improved electronic and microstructures of the proposed photoanodes.

Intrinsic Poly-Si layer thickness: Its role in pinhole contact formation and interface passivation in poly-silicon on oxide solar cells

Tunnel oxide passivating contact (TOPCon) solar cells are characterized by high surface passivation and electrical transport efficiency due to the chemical passivation and field effect of the tunnel oxide and doped poly-silicon layers, respectively. Nevertheless, the passivation quality, implied open-circuit voltage (iVoc), and device lifetime are adversely affected by high-temperature processing, leading to Auger recombination and pinhole defects in the tunnel oxide layer. This study aimed to explore the introduction of intrinsic poly-silicon as an interlayer to improve thermal stability and assesses its effect on the passivation of the tunnel oxide interface. Findings indicate that an intrinsic poly-silicon interlayer with a minimum thickness of 18 nm prevents passivation degradation at elevated temperatures. Additionally, the incorporation of this interlayer facilitates the tuning of the doping profile in crystalline silicon, resulting in a diminished pinhole density and an enhanced iVoc of 714.9 mV. These results advance our understanding of TOPCon solar cell performance and provide a foundation for their further optimization.

Design of superparamagnetic Fe3O4@SiO2@3,4-DABP nanocatalysts, fabrication by co-precipitation and sol-gel methods, characterization of detailed surface texture properties and investigation of solar cell performance

This research focuses on the synthesis, characterization, and evaluation of Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@3,4-DABP magnetic nanocatalysts (MNCs) for their potential use as sensors within the intricate architectures of solar cell devices. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area measurements were carried out to characterize the structural, morphological and magnetic properties of the MNCs. The MNCs exhibit an average particle size of approximately 10 nm. Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@3,4-DABP MNCs have saturation magnetization values ​​of 61.64 emu/g, 37.31 emu/g, and 20.13 emu/g, respectively. Thermal analysis reveals mass change losses of 6.5%, 12% and 28.1%, respectively, indicating different thermal stability profiles. It confirms that their crystal structure is face-centered cubic spinel, with type IV hysteresis loops and H3 loops indicating a mesoporous structure according to the IUPAC classification. Efficiency tests of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@3,4-DABP MNCs in solar cell devices show efficiencies of 1.49%, 1.77% and 2.15%, respectively. As the hierarchical modification of the MNCs increases, the efficiency of the solar cell devices increases. These results highlight the potential of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@3,4-DABP as promising sensitizers in solar cell technology. Fe3O4@SiO2@3,4-DABP MNCs have high catalytic activity, chemical stability, electronic conductivity and low cost. This study also marks the first demonstration of the effectiveness of environmentally friendly Fe3O4@SiO2@3,4-DABP MNCs in enhancing solar cell performance, prepared via a cost-effective, simple and eco-friendly approach.

Impact of graded CIGS absorber layer on Cd-free CIGS thin-film solar cell performance: numerical optimization

Abstract This paper investigates replacing the CdS buffer layer with (Zn, Mg)O and Zn(S, O) double buffer layers. To increase the efficiency of the structure, our strategy involves numerically studying and comparing three types of CIGS bandgap absorber layers: FB (Flat Band), Double Gradient Bandgap (DG) with a high bandgap near the Mo contact (back side), a low bandgap near the buffer layer (front side), and a minimum bandgap between them, and Simple Gradient Bandgap (SG) with a high bandgap near the Mo contact (back side) and a low bandgap near the buffer layer (front side). Each type features different linear graded profiles in the thickness direction to determine the optimal bandgap gradient of the CIGS layer. The performance of the three types is numerically analyzed using the SCAPS-1D simulator. Simulation enables us to test multiple structural combinations efficiently, saving both time and money, while providing results that guide experimental research. The proposed device structure is composed of the following layers: ZnO:Al/n-Zn1-xMgxO/n- ZnSxO1-x/p- Graded-CuIn1-xGaxSe2 /Mo. To study the effects of linear bandgap gradient distribution of Ga⁄((Ga+In) ) ratio according to the thickness direction on CIGS solar cell performance, the electrical properties of the proposed CIGS model were initially matched with experimental data to confirm the structure's accuracy. It was found that the Double Gradient Bandgap (DG), with maxima of 1.44 eV at the back side (near Mo contact), 1.238 eV at the front side (near n-type buffer layer interface), and a minimum of 1.154 eV at a position of 1.7 µm from the back side, has a higher efficiency than the other structures with 26.22% (Voc = 0.8134 V, Jsc = 37.82 mA/cm², FF = 85.21%). Optimizing the bandgap gradient of the CIGS absorber layer helps improve the efficiency of CIGS solar cells.