Chalcogenide Solar Cells Research Articles

In situ seed layer bandgap engineering leading to the conduction band offset reversion and efficient Sb2Se3 solar cells with high open-circuit voltage

Sb2Se3 solar cells have achieved a power conversion efficiency (PCE) of over 10%. However, the serious open-circuit voltage deficit (VOC-deficit), induced by the hard-to-control crystal orientation and heterojunction interface reaction, limits the PCE of vapor transport deposition (VTD) processed Sb2Se3 solar cells. To overcome the VOC-deficit problem of VTD processed Sb2Se3 solar cells, herein, an in-situ bandgap regulation strategy is innovatively proposed to prepare a wide band gap Sb2(S,Se)3 seed layer (WBSL) at CdS/Sb2Se3 heterojunction interface to improve the PCE of Sb2Se3 solar cells. The analysis results show that the introduced Sb2(S,Se)3 seed layer can enhance the [001] orientation of Sb2Se3 thin films, broaden the band gap of heterojunction interface, and realize a “Spike-like” conduction band alignment with ΔEc = 0.11 eV. In addition, thanks to the suppressed CdS/Sb2Se3 interface reaction after WBSL application, the depletion region width of Sb2Se3 solar cells is widened, and the quality of CdS/Sb2Se3 interface and the carrier transporting performance of Sb2Se3 solar cells are significantly improved as well. Moreover, the harmful Se vacancy defects near the front interface of Sb2Se3 solar cells can be greatly diminished by WBSL. Finally, the PCE of Sb2Se3 solar cells is improved from 7.0% to 7.6%; meanwhile the VOC is increased to 466 mV which is the highest value for the VTD derived Sb2Se3 solar cells. This work will provide a valuable reference for the interface and orientation regulation of antimony-based chalcogenide solar cells.

Simulation study of cadmium-free CIGS solar cell for efficiency enhancement by minimizing recombination losses through back surface field mechanism

Thin-film photovoltaic cells provide benefits over conventional first-generation technology, including lighter weight, greater flexibility, and lower power generation costs. Chalcogenide solar cells offer good efficiency and technological maturity among thin-film technology. In this work, a solar cell device structure, Al/FTO/SnS2/CIGS/CuO/Ni, is examined using SCAPS-1D. Further, by incorporating the back surface field (BSF) layer, the conversion efficiency increased from 18.93 % to 29.88 %, followed by VOC of 0.96 V, JSC of 37.07 mA cm−2, and FF of 83.71 %. This increment in device performance is owing to the lowering back surface recombination velocity and the additional hole tunnelling activity offered by the BSF layer by forming a quasi-ohmic contact, i.e. metal-semiconductor contact with negligible junction resistance relative to the total resistance of the device. Throughout this research work, the authors studied several factors such as surface recombination velocity, temperature impact, front and back contact metal work functions, parasitic resistance impact, gallium proportion, and doping density impact on CIGS solar cells. The work also included a calibration with experimental data from published sources to validate the simulation results.This paper presents a new approach for producing high-efficiency, eco-friendly CIGS solar cells with CuO back surface field mechanism.

A Review on Suppressing Nonradiative Recombination Losses in Antimony Chalcogenide Thin‐Film Solar Cell

Antimony chalcogenide solar cells have captured considerable attention in recent years with an efficiency of over 10%, due to their use of Earth‐abundant materials and superior physical characteristics. Despite these achievements, significant nonradiative recombination processes within these solar cells present a substantial obstacle to further efficiency improvements. Therefore, this review delves into the primary mechanisms responsible for nonradiative recombination losses in antimony chalcogenide solar cells. Additionally, the latest advancements in addressing these losses are summarized. Finally, potential directions for future research efforts aimed at reducing nonrecombination losses and enhancing the overall performance of these devices are outlined.

A novel Se-diffused selenization strategy to suppress bulk and interfacial defects in Sb2Se3 thin film solar cell

In recent years, vacuum-based deposition of antimony selenide (Sb2Se3) thin films has garnered significant attention owing to its easy and impurity-free fabrication, along with exceptional power conversion efficiency (PCE). However, the necessary post-selenization process comes with a shortcoming of instigating buried Sb2Se3/molybdenum (Mo) back-contact interface defects. This study introduces a novel Se-diffusion post-selenization technique to precisely regulate the selenium reaction atmosphere, preventing void formation on the Sb2Se3 thin film surface and maintaining film quality for enhanced device efficiency. An optimized selenization condition with a precise Se precursor film thickness led to obtaining highly crystalline, preferentially (hk1) oriented, and large-grained Sb2Se3 films. Furthermore, a meticulous Se diffusion in Sb2Se3 film reduced the inevitable MoSe2 layer thickness at the Mo surface, thereby enhancing the quality of the back contact interface. The Sb2Se3 solar cell that was selenized to optimal level showed significant enhancements, raising the fill factor from 40.06 % to 45.12 % and improving the device efficiency from 2.89 % to 3.57 %. Our newly developed selenization strategy establishes a successful approach to regulate the Sb2Se3 film quality by addressing a crucial challenge in improving the efficiency of antimony chalcogenide solar cells.

Research on the Performance of Fmoc-amino Acid Passivated Peroverskite Solar Cells

This study investigates the effect of surface passivation of chalcogenide solar cells by introducing Fmoc-Gly-OH amino acids. The results show that the moderate amount of Fmoc-Gly-OH modification can significantly improve the photovoltaic performance and stability of chalcogenide solar cells. With the increase of Fmoc-Gly-OH concentration, the photovoltaic conversion efficiency firstly increases and then decreases, and the best effect is reached when the concentration is 1.0 mg/ml.XRD and SEM analyses show that the crystal structure of the Fmoc-Gly-OH modified chalcocite thin films is more regular, and the defect density is obviously reduced.XPS analysis shows that the Fmoc-Gly-OH modification is able to reduce the defect state density of the chalcogenide layer. The reduction of defects was further verified by steady-state fluorescence spectroscopy analysis. In addition, the electrochemical impedance spectra and dark-state I-V curve results of the devices showed that the Fmoc-Gly-OH modification was able to reduce the non-radiative complexation and charge transport resistance, and increase the fill factor and open-circuit voltage. Finally, the effectiveness of Fmoc-Gly-OH surface passivation in enhancing the performance of chalcogenide solar cells was confirmed by the analysis of J-V curves and box plots. This study provides new ideas and methods for surface engineering of chalcogenide solar cells, which has some practical application prospects.

Rational designing of derivatives of quinoline and iso-quinoline based hole transport materials for antimony chalcogenide and perovskite solar cells

For efficient and stable perovskite solar cells, small molecule hole transporting materials possessing robust hole mobility, hydrophobicity, and exceptional film fabrication are highly desirable. Herein, we have evaluated first-principle-based structural, electrochemical, photophysical, stability, and charge transport attributes of eight novel molecules (QT-M1 to QT-M4) and (IQT-M1-IQT-M4) attained via thiophene-spacer end-group acceptor engineering in quinoline and iso-quinoline based molecules Our results revealed that the freshly fabricated molecules showed effectual coherence in dispersion, transference, and excitation of charges, these are highly required attributes for ultrafast hole mobility. Drafted molecules showed exceptional band alignment along with the perovskite light-absorbing layer, which predicts effectual hole abstraction and transportation attributes. Comparatively, lower absorption in the visible region suggests the appropriate photophysical profile and the smaller hole reorganization energy values compared to the parent molecules estimate the ultrafast hole transport attributes. Moreover, the electron excitation states analysis predicts uniform charge transportation, reduced recombination losses, and greater charge dissociation. The high negative solvation-free energy of fabricated molecules exhibited easier film formation and processability. Overall, our results predict efficient strategies for optimizing solar cell devices with improved photophysical, electrochemical, and optoelectronic attributes.

Unveiling the Role of Ge in CZTSSe Solar Cells by Advanced Micro-To-Atom Scale Characterizations.

Kesterite is an earth-abundant energy material with high predicted power conversion efficiency, making it a sustainable and promising option for photovoltaics. However, a large open circuit voltage Voc deficit due to non-radiative recombination at intrinsic defects remains a major hurdle, limiting device performance. Incorporating Ge into the kesterite structure emerges as an effective approach for enhancing performance by manipulating defects and morphology. Herein, how different amounts of Ge affect the kesterite growth pathways through the combination of advanced microscopy characterization techniques are systematically investigated. The results demonstrate the significance of incorporating Ge during the selenization process of the CZTSSe thin film. At high temperature, the Ge incorporation effectively delays the selenization process due to the formation of a ZnSe layer on top of the metal alloys through decomposition of the Cu-Zn alloy and formation of Cu-Sn alloy, subsequently forming of Cu-Sn-Se phase. Such an effect is compounded by more Ge incorporation that further postpones kesterite formation. Furthermore, introducing Ge mitigates detrimental "horizontal" grain boundaries by increasing the grain size on upper layer. The Ge incorporation strategy discussed in this study holds great promise for improving device performance and grain quality in CZTSSe and other polycrystalline chalcogenide solar cells.

High-Efficiency Perovskite Solar Cells: Progress and Prospects

The quest for sustainable and efficient energy sources has intensified the exploration of alternative materials and technologies for photovoltaics. As an emerging thin-film photovoltaic technology, chalcogenide solar cells are unanimously at the forefront of research and development due to their excellent light-absorbing capacity, low manufacturing cost, simple structure, and remarkable photovoltaic conversion efficiency. First, this paper reviews the significant progress made in the development of high-efficiency chalcogenide solar cells, including the development of material compositions, device structures, and fabrication techniques that have propelled PSCs to achieve efficiencies over 25%. The paper then highlights innovative approaches in interface engineering, tandem cell configurations, and manufacturing methods that have contributed to the high-efficiency results. While emphasizing efficiency gains, the paper outlines stability challenges, recognizing their role in the practical application of PSC technology. Finally, the paper outlines promising research avenues and technological breakthroughs that could further enhance the efficiency and application of PSCs in the global energy mix, giving them the potential for a wide range of applications in photovoltaic power generation.

A CTL-free homo-heterojunction antimony chalcogenide solar cell: Theoretical study

Exploring antimony chalcogenide as photovoltaic (PV) absorber material for solar cell is an appealing strategy. However, the conversion efficiency (η) of antimony chalcogenide solar cells including antimony selenide (Sb2Se3), antimony sulfide (Sb2S3) and antimony sulfide–selenide (Sb2(S,Se)3) lag far behind their Shockley−Queisser limit efficiency. Generally, the device PV performance of thin film heterojunction solar cells is mainly affected by the material properties of each functional layer, as well as the device architecture and heterointerface characteristics. Herein, a novel homo-heterojunction antimony chalcogenide solar cell without any carrier transport layer (CTL) consisting of FTO/(n)Sb2Se3/(p)Sb2Se3/(p)Sb2S3/Metal has been proposed. The influence of thickness, doping concentration and bulk defect density of the functional layer materials, the interface defect density at (p)Sb2Se3/(p)Sb2S3 heterointerfaces, and back contact metal work function on device PV performance have been theoretically analyzed utilized wxAMPS software. After optimization, the proposed solar cell has an open-circuit voltage (Voc) of 0.885 V, a short-circuit current density (Jsc) of 36.14 mAcm−2, a filling factor (FF) of 84.30 %, and a η of 26.97 %. These results indicate that the novel homo-heterojunction antimony chalcogenide solar cell without any CTL have the potential to become a high-efficiency PV device.

Bulk Heterojunction Antimony Selenosulfide Thin‐Film Solar Cells with Efficient Charge Extraction and Suppressed Recombination

AbstractAs an emerging earth‐abundant light harvesting material, antimony selenosulfide (Sb2(S,Se)3) has received tremendous attention for photovoltaics. Manipulating the carrier separation and recombination processes is critical to achieve high device efficiency. Compared to the conventional planar heterojunction (PHJ), the bulk heterojunction (BHJ) configuration affords great potential to enable efficient charge extraction. In this work, BHJ Sb2(S,Se)3 solar cells are constructed based on CdS nanorod arrays (NRAs). Highly ordered CdS NRAs with appropriate nanorod lengths and diameters are obtained by regulating the growth environment and screening different substrates for CdS deposition. A low‐temperature oxygen doping strategy implemented on CdS NRAs is further developed to improve the optoelectronic and defect properties as well as form a favorable cascade band structure for CdS NRAs, so as to realize more efficient charge extraction and suppressed recombination at the heterointerface. As a result, the CdS NRAs‐based superstrated BHJ Sb2(S,Se)3 solar cell yields a considerable power conversion efficiency of 8.04%, outperforming that of the PHJ device. A careful comparative study of PHJ and BHJ based on electrostatic field simulations indicates that the BHJ allows more efficient charge extraction and transport. This work highlights the great potential of BHJ configuration for constructing high‐performance antimony chalcogenide solar cells.

Current Progress of Efficient Active Layers for Organic, Chalcogenide and Perovskite-Based Solar Cells: A Perspective

Photovoltaics has become one of the emerging alternatives to progressively supply/replace conventional energy sources, considering the potential exploitation of solar energy. Depending on the nature of the light harvester to influence on its light-absorption capability and the facility to produce electricity, different generations of solar devices have been fabricated. Early studies of organic molecules (dye sensitizers) with good absorption coefficients, going through metal chalcogenides and, lastly, the timely emergence of halide perovskites, have promoted the development of novel and low-cost solar cells with promising photoconversion efficiency (PCE), close to the well-established Si-based devices. However, main drawbacks such as the degradation/photocorrosion of the active layer, the existence of intrinsic defect sites, and the inherent toxicity of the material due to the presence of some harmful elements have blocked the future commercialization of the above kind of solar cells. In this review, we highlight the current progress in achieving efficient photomaterials for organic, chalcogenides and halide perovskites-based solar cells with the purpose of achieving high PCE values, some of which are breakthroughs in this research topic, and the diverse approaches used to extend the stability of the active layer and improve the performance of the solar devices.

Zinc Chloride‐Treated Indium Sulfide as Buffer Layer for Cd‐Free Antimony Selenide Solar Cells

In2S3, as a promising environmentally benign semiconductor, is used as a buffer layer in thin‐film solar cells due to its high electron mobility, low toxicity, and excellent thermal and chemical stability. The preparation of a high‐quality In2S3 film is crucial for the improvement of its carrier extraction ability and subsequent deposition of absorber layers. Herein, it is demonstrated for the first time that a posttreatment of In2S3 film with ZnCl2 solution is able to serve as buffer layer for constructing superstrate Sb2Se3 solar cells. The posttreatment with ZnCl2 not only prevents In2S3 from excessive oxidation during annealing process, but also facilitates the growth of (hk1) orientation of Sb2Se3, thereby improving the interfacial contact of In2S3/Sb2Se3. The improved heterojunction quality suppresses the carrier recombination at the interface, and enhances the charge extraction ability of In2S3. As a result, the power conversion efficiency of Sb2Se3 solar cell increases from 2.63% to 5.00%. Herein, a facile and effective strategy is provided for the application of In2S3 as the buffer layer in inorganic chalcogenide solar cells.

A Perspective of Antimony Chalcogenide Photovoltaics toward Commercialization

Recent developments in antimony chalcogenide (Sb2X3, X = S, Se, or SxSe1−x) solar cells attract significant scientific and technological interest in the renewable energy community. Over a relatively short period, the efficiency of Sb2X3 solar cells exhibits remarkable growth, escalating from 0.66% in 2000 to 10.75% in 2023. This substantial improvement suggests the potential of Sb2X3 solar cells for commercial applications. It is essential to discuss the prospects of Sb2X3 solar cells for commercial applications, yet there is no discussion on this. In this review, the potential of Sb2X3 solar cells is systematically assessed for industrialization from two key perspectives: the basic properties of Sb2X3 materials (including toxicity, physicochemical stability, and cost) and the device performance (including large area, efficiency, levelized cost of energy, and operational stability). Additionally, an outlook on the future development trends of Sb2X3 solar cells toward the potential commercialization is also provided. Also, the insights gained from this review can be applied to other emerging solar cell technologies as well such as Cu2ZnSn(S,Se)4, GeSe, etc.

Multi‐Phase Sputtered TiO2‐Induced Current–Voltage Distortion in Sb2Se3 Solar Cells

AbstractDespite the recent success of CdS/Sb2Se3 heterojunction devices, cadmium toxicity, parasitic absorption from the relatively narrow CdS band gap (2.4 eV) and multiple reports of inter‐diffusion at the interface forming Cd(S,Se) and Sb2(S,Se)3 phases, present significant limitations to this device architecture. Among the options for alternative partner layers in antimony chalcogenide solar cells, the wide band gap, non‐toxic titanium dioxide (TiO2) has demonstrated the most promise. It is generally accepted that the anatase phase of the polymorphic TiO2 is preferred, although there is currently an absence of analysis with regard to phase influence on device performance. This work reports approaches to distinguish between TiO2 phases using both surface and bulk characterization methods. A device fabricated with a radio frequency (RF) magnetron sputtered rutile‐TiO2 window layer (FTO/TiO2/Sb2Se3/P3HT/Au) achieved an efficiency of 6.88% and near‐record short–circuit current density (Jsc) of 32.44 mA cm−2, which is comparable to established solution based TiO2 fabrication methods that produced a highly anatase‐TiO2 partner layer and a 6.91% efficiency device. The sputtered method introduces reproducibility challenges via the enhancement of interfacial charge barriers in multi‐phase TiO2 films with a rutile surface and anatase bulk. This is shown to introduce severe S‐shaped current–voltage (J–V) distortion and a drastic fill–factor (FF) reduction in these devices.

High-efficiency Sb2Se3 thin-film solar cells based on Cd(S,O) buffer layers prepared via spin-coating

CdS films prepared via chemical bath deposition exhibit extremely good performance as a buffer layer of chalcogenide solar cells. However, their commercial application is very limited because of the production of a large amount of wastewater containing cadmium. In this study, we develop an efficient way to prepare CdS films using the spin-coating technique. The spin solution is anhydrous, and the oxygen content can be well controlled by changing the Cd/S content ratio in the solution. The crystal structure, morphology, and optical and electrical properties of CdS films with different Cd/S content ratios are characterized. The effect of the oxygen content on the device performance is investigated. We find that the introduction of an appropriate amount of oxygen can improve the carrier transport efficiency by decreasing the interface recombination. The spin-coated CdS films have good coverage of the substrate for film thicknesses below 50 nm. By the optimizing of Cd/S content ratio, we achieve an improved efficiency of 5.76% for the Sb2Se3 solar cells. This preparation technique is sufficiently simple for large-scale processing and produces much less wastewater containing cadmium; thus, it is promising for application to future large-scale solar cell production.

Confined‐Space Selenium‐Assisted Tellurization Posttreatment Strategy for Efficient Full‐Inorganic Sb2S3 Thin‐Film Solar Cells

Antimony sulfide is a promising photovoltaic material because of its high absorption coefficient, green and earth‐abundant constituents, and suitable bandgap. Sb2S3 planar solar cells from evaporation method without hole‐transport layer suffer from sulfur vacancy (VS) and a high back‐contact barrier. The same group anion exchange method demonstrates an efficient solution to fill VS and suppress the back‐contact barrier. However, the same group Te exchange with sulfur treatment has to implement at high temperature, which degrades the Sb2S3 film quality. Herein, a confined‐space selenium‐assisted tellurization (c‐SeTe) posttreatment strategy is developed to overcome aforementioned challenges. Material characterizations make certain that most tellurium is distributed at the back and there is a weak signal in bulk. Further physical characterizations unfold the c‐SeTe role in device performance. The back Se and Te alloying can suppress the back‐contact barrier to improve the extraction efficiency. And, Se and Te codoping in bulk helps to passivate the interface and bulk defects so as to improve the CdS/Sb2S3 heterojunction quality and enhance the long‐wavelength photon quantum yield. Finally, a champion power conversion efficiency of 4.95% is obtained, net 0.5% higher than the control one. The robust treatment method is expected to promote the fast development of antimony chalcogenide solar cells.

“Machine micro/nano optics scientist”: Application and development of artificial intelligence in micro/nano optical design

Micro/nano optical materials and devices are the key to many optical fields such as optical communication, optical sensing, biophotonics, laser, and quantum optics, etc. At present, the design of micro/nano optics mainly relies on the numerical methods such as Finite-difference time-domain (FDTD), Finite element method (FEM) and Finite difference method (FDM). These methods bottleneck the current micro/nano optical design because of their dependence on computational resources, low innovation efficiency, and difficulties in obtaining global optimal design. Artificial intelligence (AI) has brought a new paradigm of scientific research: AI for Science, which has been successfully applied to chemistry, materials science, quantum mechanics, and particle physics. In the area of micro/nano design AI has been applied to the design research of chiral materials, power dividers, microstructured optical fibers, photonic crystal fibers, chalcogenide solar cells, plasma waveguides, etc. According to the characteristics of the micro/nano optical design objects, the datasets can be constructed in the form of parameter vectors for complex micro/nano optical designs such as hollow core anti-resonant fibers with multi-layer nested tubes, and in the form of images for simple micro/nano optical designs such as 3dB couplers. The constructed datasets are trained with artificial neural network, deep neural network and convolutional neural net algorithms to fulfill the regression or classification tasks for performance prediction or inverse design of micro/nano optics. The constructed AI models are optimized by adjusting the performance evaluation metrics such as mean square error, mean absolute error, and binary cross entropy. In this paper, the application of AI in micro/nano optics design is reviewed, the application methods of AI in micro/nano optics are summarized, and the difficulties and future development trends of AI in micro/nano optics research are analyzed and prospected.

A comprehensive insight into deep-level defect engineering in antimony chalcogenide solar cells

Antimony chalcogenides (Sb2X3, X = S and Se) are intriguing materials for flexible/wearable, lightweight, and tandem photovoltaic devices. This work highlights the deep-level defect engineering strategies for Sb2X3 thin-film solar cells.

Self-passivation hole-transporting materials with pyridine-containing cores for antimony chalcogenide solar cells studied under dopant-free conditions

The pyridine heterocycle was applied as a passivation group for Sb2(S,Se)3 solar cells for the first time. Pyridine-containing HTMs could decrease the number of interfacial defects and improve the photovoltaic performance and long-term stability.

Asymmetric NDI electron transporting SAM materials for application in photovoltaic devices

New electron transporting materials containing 1,4,5,8,-naphtalenetetracarboxylic diimide central fragment along with various anchoring groups were synthesized and investigated for possible application in photovoltaic devices. These semiconductors demonstrated good thermal stability and suitable electrochemical properties for effective electron transport from absorber layer to cathode. Self-assembled monolayers of reported derivatives have shown increased contact angle, which indicates bond formation between monolayer forming molecules and Sb2S3, Sb2Se3 or perovskite surface. Favorable energetic band alignment and possibility to modify absorber layer surface makes them promising candidates for application in perovskite or antimony chalcogenide solar cells.