Solar Cells Research Articles

An Effective Precursor‐Solutioned Strategy for Developing Cu2ZnSn(S, Se)4 Thin Film Toward High Efficiency Solar Cell

AbstractEnhancing the efficiency of Cu2ZnSn (S, Se)4 (CZTSSe) thin‐film solar cells requires the development of well‐crystallized light‐absorbing layers. A deep understanding of the role of precursor solution chemistry in film nucleation and crystal growth processes is essential. Insights into these processes enable the development of innovative strategies to enhance absorber quality, minimize detrimental bulk defects, and ultimately improve device performance. This study elucidates the condensation reactions between thiourea and metal cations, as well as the alcoholysis of 2‐methoxyethanol (MOE), at different concentrations of precursor solutions. The primary focus of this study is implementing a simple and environmentally friendly innovative spin‐coating strategy, aimed at optimizing Cu2ZnSnS4 (CZTS) precursor films and adjusting the Se content within the film bulk to promote grain growth during selenization. This strategy effectively improves absorber morphology while suppressing the formation of deep‐level defects, thereby enhancing carrier transport in both interfacial and bulk regions of the absorber layer. Consequently, CZTSSe absorbers with enhanced crystallinity and reduced defects are synthesized, resulting in a solar cell with an impressive efficiency of 14.10%. These findings underscore the potential for creating highly efficient kesterite CZTSSe solar cells through the manipulation of precursor solution chemistry using environmentally friendly solvents.

Correlation of Band Bending and Ionic Losses in 1.68 eV Wide Band Gap Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs) are promising for high‐efficiency tandem applications, but their long‐term stability, particularly due to ion migration, remains a challenge. Despite progress in stabilizing PSCs, they still fall short compared to mature technologies like silicon. This study explores how different piperazinium salt treatments using iodide, chloride, tosylate, and bistriflimide anions affect the energetics, carrier dynamics, and stability of 1.68 eV bandgap PSCs. Chloride‐based treatments achieved the highest power conversion efficiency (21.5%) and open‐circuit voltage (1.28 V), correlating with stronger band bending and n‐type character at the surface. At the same time, they showed reduced long‐term stability due to increased ionic losses. Tosylate‐treated devices offered the best balance, retaining 96.4% efficiency after 1000 h (ISOS‐LC‐1I). These findings suggest that targeted surface treatments can enhance both efficiency and stability in PSCs.

UV Irradiation as a Versatile Low-Temperature Strategy for Fabricating Templated Mesoporous Titania Films.

Mesoporous titania thin films offer promising applications in sensors, batteries, and solar cells. The traditional soft templating methods rely on high-temperature calcination, which is energy-intensive, incompatible with thermosensitive flexible substrates, and destructive for titania structures. This work demonstrates UV irradiation as a versatile low-temperature and energy-saving alternative for mesoporous crystalline titania fabrication. Grazing incidence wide-angle X-ray scattering analysis reveals a three-stage crystallization process with increasing UV irradiation time supported by photoluminescence data. UV-irradiation-derived samples exhibit crystallinity and crystal size comparable to that of calcination. Integration with block copolymer templated sol-gel synthesis enables the creation of various morphologies, including cylindrical, ordered spherical, and hybrid structures. Characterizations via scanning electron microscopy and grazing incidence small-angle X-ray scattering confirm the homogeneity of morphology in the resulting films. The resulting films maintain similar optical properties despite morphological differences, as demonstrated by photoluminescence and UV-vis measurements. The versatility of UV irradiation extends to different titanium precursors, underscoring it as a flexible and efficient method for mesoporous titania thin film fabrication at low temperatures.

Carboxymethyl‐Based Ionic Liquid Engineering for Efficient and Stable Inverted Perovskite Solar Cells

Perovskite solar cells (PSCs) have garnered significant attention due to their tunable bandgap, superior charge carrier properties, and easy fabrication processes, making them highly efficient energy conversion devices. Despite these advantages, nonradiative recombination due to defects in the perovskite layer continues to limit performance. This study addresses this issue by introducing 1‐CarboxyMethyl‐3‐MethylImidazolium chloride (ImAcCl) into precursor solution to enhance film quality and suppress defect‐induced recombination. The carboxylate groups (CO) and hydrogen donors (NH) in ImAcCl form coordination and hydrogen bonds, helping to reduce defect density of the perovskite film. Additive ImAcCl improves crystallinity, reduces surface roughness, and enhances charge carrier transport, leading to higher photovoltaic performance. With the ImAcCl additive, the power conversion efficiency and short‐circuit current of PSCs significantly improve by 23.92% and 25.35 mA cm−2, with a notable reduction in nonradiative recombination losses. This study highlights the significant potential of ImAcCl as an effective additive for defect passivation in PSCs, offering a promising pathway toward further efficiency improvements in next‐generation solar cells.

Tailoring Ga‐Doped ZnO Thin Film Properties for Enhanced Optoelectric Device Performance: Argon Flow Rate Modulation and Dynamic Sputtering Geometry Analysis

The impact of dynamic sputtering geometry on the properties of ZnO: Ga (GZO) thin film nanomaterials is investigated by systematically varying Ar flow rates and substrate positions during the film growth. The structural, optical, and electrical characteristics of GZO layers, deposited from a ZnO: Ga (5.7 wt%) ceramic‐type sputtering target, are comprehensively evaluated to reveal the relationship between the sputtering geometry and material properties. The obtained electrical properties, comparatively high carrier mobility 11.3 × 101 cm2 V−1 s−1 and the lowest resistivity 1.13 × 10−3 Ω‐cm, together with a moderately high optoelectric figure of merit with the films prepared using around 6 sccm Ar‐flow rate (corresponding to around 4.92 mTorr Ar partial pressure) reveal distinct correlations between the sputtering conditions and thin film properties, providing insights into the optimization of sputtering parameters for tailored material synthesis required for advanced and emerging applications. The GZO thin film (prepared with the optimal setting of 6 sccm Ar flow rate) exhibits remarkable optoelectronic capabilities as a transport layer in solar cells, reaching peak efficiencies of 26.34% for CIGS, 14.142% for CdTe, and 24.289% for Cs2AgBiBr6 perovskite in SCAPS‐1D simulated models. This study advances sputtering techniques for precise engineering of functional nanomaterials with enhanced performance and versatility, contributing to material synthesis optimization for emerging applications.

Effect of titanium dioxide nanofillers on the properties of gel-polymer electrolytes and power conversion efficiency of dye-sensitized solar cells

Effect of titanium dioxide nanofillers on the properties of gel-polymer electrolytes and power conversion efficiency of dye-sensitized solar cells

Surface p‐Type Self‐Doping Facilitating the Enhanced Performance of Air‐Processed Carbon‐Based Perovskite Solar Cells

The fabrication of perovskite solar cells (PSCs) in the ambient environment offers considerable promise for practical applications, yet it also poses considerable challenges. Water is known to cause structural deterioration, which has a negative effect on the stability and efficiency of perovskite‐based devices. The presence of defects is believed to provide pathways for water infiltration into the perovskite. Therefore, one important strategy for avoiding perovskite hydration is the passivation of perovskite defects. Herein, a simple antisolvent additive engineering approach is employed. By adding the additive with functional groups of CO, NH2, and CF3 to the antisolvent ethyl acetate, the defects in the perovskite thin film are successfully reduced and significantly mitigated the possibility of H2O infiltrating the perovskite lattice through the defects. Additionally, the addition of methyl 2‐amino‐4‐(trifluoromethyl)benzoate results in a p‐type self‐doping effect at the interface of the perovskite film, thereby improving hole extraction and transport. The power conversion efficiency of hole‐transport layer‐free carbon‐based PSCs fabricated in ambient air conditions is 19.17% (0.04 cm2) and 17.78% (1 cm2), respectively. Moreover, the optimized unencapsulated devices retain 90.6% of their original efficiency after being kept for 1200 h in conditions of 70% relative humidity.

Unveiling the Influence of Additive Acidity on the Long-Term Stability of Perovskite Solar Cells

Unveiling the Influence of Additive Acidity on the Long-Term Stability of Perovskite Solar Cells

Program-Modulated Kinetics of Perovskite-Film Growth by Molecular "Thruster"for High-Efficiency and Stable Perovskite Solar Cells.

The rapid reaction between lead iodide (PbI2) and formamidinium iodide (FAI) complicates the fabrication of high-quality formamidinium lead iodide (FAPbI3) films. Conventional methods, such as using nonvolatile small molecular additives to slow the reaction, often result in buried interfacial voids and molecule diffusion, compromising the devices' operational stability. In this study, we introduced a molecular "thruster"-a hypervalent iodine (III) compound with three carbonyl groups and a C--I⁺ bond-that possessescoordination and dissociation abilities, enabling programed modulation of perovskite-film growth kinetics. Initially, the three carbonyl groups coordinate with PbI2 to slow the reaction between FAI and PbI2, preventing δ-phaseformation. As temperature rises, the C--I⁺ bond dissociates, promoting perovskite growth and the dissociated product iodobenzene will promote solvent volatilization, thus avoiding buried interfacial voids. Another product, a carbene compound with eight lone pair electrons sufficiently passivate the undercoordinated Pb2+ defects and anchors at grain boundaries without diffusion. Consequently, the resultant FAPbI3 film displayshigh-quality with enhanced phase purity, compact morphology, and reduced defects. Evidently, 0.062- and 1.004-cm2 pero-SCs achieve power conversion efficiencies (PCEs) of up to 26.06% (25.79% certified) and 24.65%, respectively. This approach alsocontrols perovskite-film growth on plastic substrates, resulting in flexible pero-SCs with an impressive PCE of 25.12%.

Bilayered Phosphorus‐Doped Polysilicon Passivating Contact Structures for TOPCon Solar Cell Applications

ABSTRACTThe use of single‐layer polysilicon (poly‐Si) in tunnel oxide passivated contact (TOPCon) structures has demonstrated excellent passivation and contact performance. However, commercial TOPCon solar cell fabrication requires screen‐printing and cofiring techniques for electrode preparation. The single‐layer structure is less efficient at preventing metal atoms in the electrode paste from penetrating the silicon bulk. Furthermore, the uniformity of doping concentration and crystallinity within this structure poses challenges as it fails to optimally meet the intricate requirements for achieving superior performance in terms of passivation, contact, and mitigating parasitic absorption. In this study, the deposition process of the amorphous silicon (a‐Si) precursor layer using an in‐line magnetron sputtering system incorporated an additional plasma oxidation step, resulting in a bilayer poly‐Si structure with the newly introduced SiOx acting as a partition. Detailed investigations were conducted into the passivation quality, contact resistivity, crystallinity, and the distribution of critical atoms in the bilayer structure. Subsequently, the bilayer configuration was utilized in the manufacturing process of TOPCon solar cells. These efforts resulted in a notable enhancement in open‐circuit voltage (Voc) and short‐circuit current (Isc), leading to a 0.06% efficiency improvement, based on the average performance of ~200 cells per group.

Advancements in Manufacturing of High-Performance Perovskite Solar Cells and Modules Using Printing Technologies

Perovskite photovoltaic technology carries immense opportunity for the solar industries because of its remarkable efficiency and prospect for cost-effective production. However, the successful deployment of perovskite solar modules (PSMs) in the solar market necessitates tackling stability-based obstacles, scalability, and environmental considerations. This paper unveils a comprehensive examination of the cutting-edge advancements in the manufacturing of perovskite solar cells (PSCs) and modules, with an emphasis on high-speed, large-area printing. The paper underscores the substantial progress achieved in printed PSCs and PSMs, demonstrating promising electrical performance and long-term device durability. This review paper categorizes printing techniques compatible with large-area high-speed manufacturing into three distinct families: blade coating, slot die coating, and screen printing, as these common printing practices offer precise control, scalability, cost-effectiveness, high resolution, and efficient material usage. Additionally, this paper presents an in-depth investigation and comparison of superior PSCs and PSMs fabricated by printing on power conversion efficiency (PCE), stability, and scalability.

Computational Screening of Two-Dimensional Lead-Free Halide Double Perovskites for Solar Cells

Computational Screening of Two-Dimensional Lead-Free Halide Double Perovskites for Solar Cells

Program‐Modulated Kinetics of Perovskite‐Film Growth by Molecular "Thruster" for High‐Efficiency and Stable Perovskite Solar Cells

The rapid reaction between lead iodide (PbI2) and formamidinium iodide (FAI) complicates the fabrication of high‐quality formamidinium lead iodide (FAPbI3) films. Conventional methods, such as using nonvolatile small molecular additives to slow the reaction, often result in buried interfacial voids and molecule diffusion, compromising the devices' operational stability. In this study, we introduced a molecular “thruster”—a hypervalent iodine (III) compound with three carbonyl groups and a C––I⁺ bond—that possesses coordination and dissociation abilities, enabling programed modulation of perovskite‐film growth kinetics. Initially, the three carbonyl groups coordinate with PbI2 to slow the reaction between FAI and PbI2, preventing δ‐phase formation. As temperature rises, the C––I⁺ bond dissociates, promoting perovskite growth and the dissociated product iodobenzene will promote solvent volatilization, thus avoiding buried interfacial voids. Another product, a carbene compound with eight lone pair electrons sufficiently passivate the undercoordinated Pb2+ defects and anchors at grain boundaries without diffusion. Consequently, the resultant FAPbI3 film displays high‐quality with enhanced phase purity, compact morphology, and reduced defects. Evidently, 0.062‐ and 1.004‐cm2 pero‐SCs achieve power conversion efficiencies (PCEs) of up to 26.06% (25.79% certified) and 24.65%, respectively. This approach also controls perovskite‐film growth on plastic substrates, resulting in flexible pero‐SCs with an impressive PCE of 25.12%.

Influence of Copper and Tin Oxidation States on the Phase Evolution of Solution-Processed Ag-Alloyed CZTS Photovoltaic Absorbers

Kesterite-based semiconductors, particularly copper–zinc–tin–sulfide (CZTS), have garnered considerable attention as potential absorber layers in thin-film solar cells because of their abundance, nontoxicity, and cost-effectiveness. In this study, we explored the synthesis of Ag-alloyed CZTS (ACZTS) materials via the sol–gel method and deposited them on a transparent fluorine-doped tin oxide (FTO) back electrode. A key challenge is the selection and manipulation of metal–salt precursors, with a particular focus on the oxidation states of copper (Cu) and tin (Sn) ions. Two distinct protocols, varying the oxidation states of the Cu and Sn ions, were employed to synthesize the ACZTS materials. The transfer from the solution to the precursor film was analyzed, followed by annealing at different temperatures under a sulfur atmosphere to investigate the behavior and growth of these materials during the final stage of annealing. Our results show that the precursor transformation from solution to film is highly sensitive to the oxidation states of these metal ions, significantly influencing the chemical reactions during sol–gel synthesis and subsequent annealing. Furthermore, the formation pathway of the kesterite phase at elevated temperatures differs between the two protocols. Structural, morphological, and optical properties were characterized via X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Our findings highlight the critical role of the Cu and Sn oxidation states in the formation of high-quality kesterite materials. Additionally, we studied a novel approach for controlling the synthesis and phase evolution of kesterite materials via molecular inks, which could provide new opportunities for enhancing the efficiency of thin-film solar cells.

Enhancing Power Conversion Efficiency of Perovskite Solar Cells Through Machine Learning Guided Experimental Strategies

AbstractPredicting the power conversion efficiency (PCE) using machine learning (ML) can effectively accelerate the experimental process of perovskite solar cells (PSCs). In this study, a high‐quality dataset containing 2079 experimental PSCs is established to predict PCE values using an accurate ML model, achieving an impressive coefficient of determination (R2) value of 0.76. In the 12 validation experiments with PSCs, the average absolute error between the observed and predicted PCE values is only 1.6%. Leveraging the recommended improvement solutions from the ML model, the device's PCE to 25.01% in experimental PSCs is successfully enhanced, thus truly realizing the objective of machine learning‐guided experiments. In addition, by improving the PCE of specific devices, the predicted value can reach 28.19%. The ML model has provided feasible strategies for experimentally improving the PCE of PSCs, which play a crucial role in achieving PCE breakthroughs.

Minimizing Performance Loss in Blade‐Coated Large‐Area Perovskite Solar Cells Via Semi‐Sealed Gas Quenching

AbstractGas‐quenching of perovskite wet films is widely used in upscaling perovskite solar cells (PSCs). However, due to uneven and turbulent gas stream generated by traditional approaches through air knife or air gun, it is a challenge to induce homogeneous nucleation and produce high‐quality perovskite films suitable for large‐area PSCs. Here this work presents a semi‐sealed gas quenching (SSGQ) strategy that produces homogeneous low‐velocity large‐area high‐pressure gas flow to extract low‐boiling‐point solvents effectively, while leaving behind perovskite intermediates undisturbed that then turn into large crystalline grains. As a result, the SSGQ‐processed perovskite films exhibit improved crystallinity and reproducibility, suppressed defect density and residual stress, as well as compact buried interface and large‐scale uniformity. Such blade‐coated large‐area (1.0 cm2) PSCs with carbon and metal electrodes achieve high power conversion efficiencies (PCEs) of 19.5% and 23.3% (20.5% and 24.2% for 0.04 cm2), both with the lowest PCE loss of ≤1.0% among reported works. This work presents a scalable and affordable approach for fabricating high‐quality perovskite films and high‐performance perovskite photovoltaics, paving the way to PSC commercialization.

Regulation of Interface Schottky Barrier and Photoelectric Properties in Carbon-Based HTL-Free Perovskite Solar Cells.

Carbon-based hole transport layer (HTL)-free perovskite solar cells (C-PSCs) receive a lot of attention because of their simplified preparation technology, low price, and good hydrophobicity. However, the Schottky junction formed at the interface between perovskite and carbon poles affects the photogenerated carrier extraction and conversion efficiency. In this paper, 4-trifluoromethyl-2-pyridinecarboxylic acid (TPCA) is used to modify the perovskite films. The introduction of TPCA can reduce the p-type Schottky barrier height (p-SBH) and thin the Schottky barrier width W, which greatly improves the hole transport ability and tunneling probability. Meanwhile, the n-type Schottky barrier height (n-SBH) shows a rising trend, which prevents the reverse electron transport to carbon, suppresses unnecessary carrier complexes, and greatly improves the device's optoelectronic performance. Besides, the pyridine nitrogen and C=O in TPCA interact with Pb2+ to raise the crystal quality of perovskite films while inhibiting nonradiative recombination. The results show that compared with the pristine device's 11.45% photoelectric conversion efficiency （PCE), the TPCA-modified device achieves 13.64% PCE. The device's long-term stability significantly improved post-TPCA modification. After 720h of storage at room temperature and 40-60% relative humidity in the air, the unencapsulated device retained 77% of its initial efficiency.

Copper Precursor-Driven Variations in Structural, Optical and Electrical Properties of SILAR-Deposited CTS Thin Films

Abstract This pioneering study elucidates, for the first time, the profound impact of copper precursors (copper acetate, copper sulfate, and copper chloride) on the structural, optical, and electrical properties of Copper Tin Sulfide (CTS) thin films synthesized via successive ionic layer adsorption and reaction (SILAR) deposition. Comprehensive characterization using X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and electrical and optical measurements revealed significant variations in crystallite size (59.3-76.4 nm), film thickness (1.235-4.75 µm), and conductance (3.7-6.4 × 10-11 S). Notably, copper chloride-derived films exhibited enhanced surface morphology, maximum bandgap energy (3.7 eV), and highest conductance, with displaying unique optical properties, including zero transmittance below 300 nm, low absorption above 300 nm, and a balanced absorption profile, making them ideal for photovoltaic cells, optical sensors, and UV-blocking applications. These results demonstrate the critical influence of copper precursors on CTS thin film properties, paving the way for tailored material design and enhanced device performance, with significant implications for the development of efficient and sustainable photovoltaic technologies.

Highly Efficient Lightweight Flexible Cu(In,Ga)Se2 Solar Cells with a Narrow Bandgap Fabricated on Polyimide Substrates: Impact of Ag Alloying, Cs and Na Doping, and Front Shallow Ga Grading on Cell Performance

Herein, lightweight, flexible Cu(In,Ga)Se2 (CIGS) solar cells with a narrow bandgap of ≈1 eV are grown on polyimide substrates. The poor performance of the CIGS solar cells owing to a low growth temperature (≈400 °C) is considerably improved via Ag alloying, Na doping using alkali‐silicate‐glass thin layers (ASTLs) and the CsF postdeposition treatment (CsF‐PDT), and front shallow Ga grading (surface field; SF). Along with improved device process, a notably high conversion efficiency of 21.2%, low VOC deficit of 0.346 V, and high JSC of ≈40 mA cm−2 are achieved. Ag alloying and Na doping using ASTLs predominantly improve the CIGS bulk quality, while the CsF‐PDT and SF reduce carrier recombination at the CIGS/CdS interface and vicinity. Device simulations reveal that the SF increases the electrical field at the CIGS surface under the forward bias voltage close to VOC owing to electron injection from the CdS side, which increases the chemical potential. Thus, the SF effectively repulses holes and improves the interfacial property. Device simulations also reveal that a high CIGS absorber's quality is prerequisite to benefit from the SF. Thus, CIGS solar cells showing improved bulk quality due to optimum alkali doping and Ag alloying considerably benefit from the SF.

Modeling of PV System Supported Intelligent Irrigation System in Iraq-Mosul Region

In this study, Matlab/Simulink is used to create a smart irrigation system that uses electricity generated by photovoltaic cells. In order to supply 90000 liters of water every irrigation period to meet the daily needs of farm irrigation, the system is intended for a rural location of Mosul city in the west. According to calculations, the necessary amount of water can be drawn from a 50 m water head well using a solar cell array that provides a submersible BLDC pump with a power of 1400 W. Employing smart irrigation demonstrated that the system's efficiency was increased and that it was more affordable than a standard pumping system. It is advised that Iraq, one of the solar-richest nations, employ smart irrigation systems, even though it now lacks energy.