Alternative Absorber Materials Research Articles

Spectroscopic screening and performance parameters of hybrid perovskite (CH3CH2PH3PbI3) using WIEN2k and SCAPS-1d

Herein, we propose that the commonly used methylammonium cation (CH3NH3+) in CH3NH3PbI3 (MAPbI3) be replaced with ethyl-phosphonium cation CH3CH2PH3+ (EP+), allowing stronger electronic coupling between the PbI6 octahedra and the organic cation and thereby increasing its stability. This paper will examine EP + based hybrid perovskite (CH3CH2PH3PbI3 or EPPbI3) as an alternative absorber material for photovoltaic cells of high efficiency and that too at affordable processing costs. By using FP-LAPW + lo methodology as used in density functional theory (DFT), we have examined physical features such as the bandgap energy, distribution of valence electron density, DOS, and optical and thermodynamical coefficients. We also simulated the performance of solar cells by employing EPPbI3 as PVA material using SCAPS-1D. The findings of the current study viz. an absorption coefficient surpassing 104 cm−1, a direct forbidden energy gap of 1.388 eV and simulated PCE of 31.8%, is enough to support applicability EPPbI3 perovskite as a PVA material.

Designing next-generation kesterite solar cells: A systematic numerical investigation of innovative structures and design variants for enhanced photovoltaic performance

This paper presents a thorough numerical investigation of copper zinc tin sulfide (CZTS)-based solar cells utilizing the SCAPS-1D simulation tool. In light of the scarcity of indium and gallium, CZTS is explored as a promising alternative absorber material. The study encompasses an extensive array of 280 device simulations, including a systematic optimization process targeting enhanced power conversion efficiency (PCE). Notably, this iterative optimization procedure results in a notable PCE increase from 11.01% to 14.24%. By delving into the realm of electron transport layer (ETL) materials, the integration of a CdO layer culminates in a significant PCE milestone of 15.71%, and a new structure was extrapolated from this step Back contact/CZTS/CdO/ZnO. Furthermore, an exploration involving 172 diverse configurations incorporating various hole transport layer (HTL) materials unveils a remarkable peak PCE of 21.14% (Back contact/SnS/CZTS/CdSe/ZnO). These findings provide valuable insights and directives for the advancement and optimization of CZTS-based solar cells.

Attenuated phase shift masks: a wild card resolution enhancement for extreme ultraviolet lithography?

Background: The successful introduction of extreme ultraviolet (EUV) lithography to high volume manufacturing has increased the interest to push this technology to its ultimate limits. This will require photoresist materials, which enable a better tradeoff between resolution, linewidth roughness and sensitivity, and the adaptation of optical resolution enhancements that were originally developed for deep ultraviolet (DUV) lithography. Aim: We review published research on attenuated phase shift masks (attPSM) for EUV with special emphasis on modeling and fundamental understanding of the imaging characteristics of alternative absorber materials. The overview on previous work is intended to summarize typical observations and learning on obtained results and to serve as a reference for further research on this important topic. Review approach: The review starts with a summary of related work on attPSM for DUV lithography. It is shown that the understanding and mitigation of mask topography (or mask 3D) effects is key for the analysis and optimization of attPSM for EUV lithography. Observations from several research groups and application of dedicated modeling approaches help to understand the physical mechanisms behind observed lateral image shifts and pitch-dependent shifts of the best focus position. Results: The imaging physics of attPSM for EUV lithography differs significantly from attPSM imaging in DUV lithography. The “double diffraction” of EUV light from the absorber, the reflection characteristics of the multilayer blank, and the guidance of light through the openings in a low-refractive-index (low-n) absorber introduce important effects that need to be considered in the design and use of attPSM in EUV lithography. It is important to use the optical properties (n and k) and the thickness of the absorber as predictive design parameters of attPSM for EUV lithography (instead of phase and reflectivity). The refractive index of the absorber material is important for binary masks as well. The discussion of low-n absorbers includes both “traditional” attPSM for EUV and low reflectivity absorbers, which exploit the guidance of light inside patterned layers. Conclusions: In-depth modeling investigations of attPSM and first experiments suggest that absorbers with a refractive index around 0.9 (low-n materials) can help to push high NA EUV lithography into the low k1 regime. Comprehensive optimization of source and mask is required to exploit the advantages of low-n absorbers. Further enhancements can help to push EUV imaging to its ultimate limit.

The Role of SnF2 Additive on Interface Formation in All Lead‐Free FASnI3 Perovskite Solar Cells

AbstractTin‐based perovskites are promising alternative absorber materials for lead‐free perovskite solar cells but need strategies to avoid fast tin (Sn) oxidation. Generally, this reaction can be slowed down by the addition of tin fluoride (SnF2) to the perovskite precursor solution, which also improves the perovskite layer morphology. Here, this work analyzes the spatial distribution of the additive within formamidinium tin triiodide (FASnI3) films deposited on top of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting layers. Employing time‐of‐flight secondary ion mass spectrometry and a combination of hard and soft X‐ray photoelectron spectroscopy, it is found that SnF2 preferably accumulates at the PEDOT:PSS/perovskite interface, accompanied by the formation of an ultrathin SnS interlayer with an effective thickness of ≈1.2 nm.

Defects properties and vacancy diffusion in Cu2MgSnS4

Cu2ZnSnS4 (CZTS) is a promising photovoltaic absorber material, however, efficiency is largely hindered by potential fluctuation and a band tailing problem due to the abundance of defect complexes and low formation energy of an intrinsic CuZn defect. Alternatives to CZTS by group I, II, or IV element replacement to circumvent this challenge has grown research interest. In this work, using a hybrid (HSE06) functional, we demonstrated the qualitative similarity of defect thermodynamics and electronic properties in Cu2MgSnS4 (CMTS) to CZTS. We show SnMg to be abundant when in Sn- and Cu-rich condition, which can be detrimental, while defect properties are largely similar to CZTS in Sn- and Cu-poor. Under Sn- and Cu-poor chemical potential, there is a general increase in formation energy in most defects except SnMg, CuMg remains as the main contribution to p-type carriers, and SnMg may be detrimental because of a deep defect level in the mid gap and the possibility of forming defect complex SnMg+MgSn. Vacancy diffusion is studied using generalized gradient approximation, and we find similar vacancy diffusion properties for Cu vacancy and lower diffusion barrier for Mg vacancy, which may reduce possible Cu-Mg disorder in CMTS. These findings further confirm the feasibility of CMTS as an alternative absorber material to CZTS and suggest the possibility for tuning defect properties of CZTS, which is crucial for high photovoltaic performance.

Tin as an Emerging Surrogate for Lead-free Perovskite Solar Cells

Perovskite-based photovoltaic technology has gained significant attention owing to its tunable electrical and optical properties. Among them, lead-based perovskites are considered as the most efficient one that delivers maximum power conversion efficiency with ample stability. In the current scenario, the perovskite-based solar cells (PSCs) can be classified into two main categories, i.e. highly efficient lead-containing and underperforming lead-free based. Even though lead-based PSCs delivers high efficiency, it loses the charm in the context of lead toxicity. The toxicity issue related to lead stands as a barrier to the commercialization of lead-based PSCs. To date, various materials have been prepared and implemented as an alternative to lead in the absorber layer. Tin (Sn) based perovskites are explored as an alternative absorber material owing to their photovoltaic properties that are comparable to lead. Tin-based perovskites exhibit some drawbacks, such as rapid crystallization, lack of oxidation stability, etc. Many research groups have addressed the problems regarding tin-based perovskites and modified its structural and morphological aspects through compositional engineering and functional additives and managed to obtain an efficiency of around 10%. In this review, we portray the state of the art developments of tin-based PSCs and their future perspectives.

Thermodynamic calculation of S−Sb system and Cu−S−Sb system

Sb2S3 and CuSbS2 have been proposed as alternative earth-abundant absorber materials for thin-film solar cells. However, no thermodynamic study of the S−Sb binary system and the Cu−S−Sb ternary system were investigated. In this paper, The S−Sb system and the Cu−S−Sb system are calculated utilizing the so-called CALPHAD (CALculation of PHAse Diagrams) technique. Using TEM-EDS and XRD, Cu0.9Sb1S2 is experimentally confirmed at the Cu1Sb1S2 and Sb2S3 two-phases region in the isothermal section at 673 K of the Cu−S−Sb ternary system. Given the asymmetric shape and miscibility gap of the liquidus in the S−Sb phase diagram, the associate solution model for the liquid phase is adopted. The solution phases (liquid, bcc, fcc) are treated with the Redlich–Kister equation. The compounds S3Sb2, Cu3SbS3, Cu12Sb4S13, CuSbS2, and Cu3SbS4 are described as a stoichiometric compound. A set of self-consistent thermodynamic parameters of the S−Sb binary system and the Cu−S−Sb ternary system are obtained. The calculated results are in good agreement with the experimental data. This study provides a set of reliable thermodynamic parameters to the Cu−Sb−S thermodynamic database, and a cost-effective tool to design material synthesis experiments and manufacturing processes.

Analysis of Se Co-evaporation and Post-selenization for Sb2Se3-Based Solar Cells

Sb2Se3 is a promising alternative absorber material for thin-film solar cells. However, by a thermal evaporation technique, it appears to partially decompose, leading to Se deficiency. In this work, we propose two alternative routes for the supply of selenium in the deposition of Sb2Se3 thin films. The first method is the co-evaporation of Se and Sb2Se3, while the second is the post-deposition selenization. Superstrate glass/FTO/TO/CdS/Sb2Se3/Au-configured thin-film cells are grown using thermal evaporation. X-ray diffraction patterns confirm the presence of CdS peaks along with the preferred (hk1) oriented grains, which are suppressed upon selenization. Modified surface morphology for the selenized samples is observed by atomic force microscopy. Enhanced current density is observed by J–V characterization and also confirmed by a remarkable external quantum efficiency (EQE) gain at long wavelengths. However, CdS deterioration reduces the EQE response in the short wavelength region, acting as a limiting factor for the efficiency improvement. The champion cell shows a power conversion efficiency of 3.6% with an open circuit voltage of 352 mV and a fill factor of 44.2%, which results in, to our knowledge, the highest value for thermally evaporated Sb2Se3 in superstrate configuration.

Study on reactivity control strategies for the thermoelectric integrated space nuclear reactor

The Autonomous Circulation Miniature Integrated nuclear Reactor (ACMIR) has features of compact structure, high power density and high efficiency. The reactivity control strategy is an important aspect in the design of ACMIR, which is essential for reactor safe operation. In this paper, two ex-core reactivity control options, namely, the rotating control drums and sliding reflector segments, were investigated. Furthermore, an optimization design was conducted on both strategies, including alternative absorber materials, thickness of absorber, absorber angle and the thickness of reflector. Finally, we analyzed and compared the neutronic characteristics with different control schemes, including the reactivity insertion behavior, reactivity temperature coefficient, submersion criticality and spatial power distribution. This work helps to improve the safety characteristics of ACMIR in reactivity control and operation.

P-type Cu3BiS3 thin films for solar cell absorber layer via one stage thermal evaporation

Ternary copper sulphides, especially copper-bismuth-sulphide (Cu-Bi-S), are alternative solar absorber materials due to their earth-abundant and non-toxic constituent elements, compared to the conventional copper indium gallium sulphide and cadmium telluride films. In this study, Cu-Bi-S thin films were deposited onto soda lime glass substrates using a one stage co-evaporation process from Cu2S and Bi2S3 sources, with the deposition temperatures varied from room temperature to 400 °C. X-ray diffraction analysis confirmed that Cu3BiS3 was the dominant phase in the Cu-rich films, and the crystalline quality of the films was significantly improved with increasing the deposition temperature. An optical bandgap of 1.4 eV was achieved for the film deposited at 400 °C, which demonstrated a Hall mobility of 3.95 cm2/V-s and a carrier concentration of 7.48 × 1016 cm−3. Cu3BiS3 films deposited at 375 and 400 °C were implemented into superstrate solar cell structures (glass/ITO/n-CdS/p-Cu3BiS3/Al).

Assessing stability of metal tellurides as alternative photomask materials for extreme ultraviolet lithography

Tellurium (Te) is one of the elements with highest extinction coefficient κ at the 13.5 nm extreme-ultraviolet (EUV) wavelength. It is being considered as an alternative absorber material for binary photomasks in EUV lithography. The absorber material is required to remain chemically stable during EUV exposure, at elevated temperatures up to 150 °C, during mask cleaning, and in the low hydrogen pressure environment that is present in the EUV scanner. However, Te is known to react with oxygen and hydrogen, forming less EUV absorbing TeO2 and more volatile H2Te, respectively. Since the melting temperature of Te is only 449.5 °C at normal pressure, alloying Te with a more stable metal might result in a high κ material that will remain thermally and chemically stable over a wider range of operating conditions. In this paper, the authors report on the stability assessment of metal telluride (M-Te) alloys for the EUV absorber material. They combined Te with high κ metals, noble metals, and etchable metals. High κ and noble M-Te materials are both thermally more stable than etchable M-Te, but they cannot be patterned easily for use in an EUV photomask. High κ M-Te exhibits polycrystal morphology at room temperature compared to quasiamorphous noble M-Te though both can crystallize at a higher temperature. Hydrogen stability and cleaning solution stability of M-Te materials are improved considerably compared to Te, but their higher surface reactivity cannot be completely mitigated without the addition of an inert capping layer. Furthermore, etchable M-Te alloys are easily oxidized during deposition, resulting in lower electron density and hence lower κ. Nevertheless, M-Te alloys may be a way to stabilize Te for usage as the EUV absorber material.

Highly efficient and stable planar heterojunction solar cell based on sputtered and post-selenized Sb2Se3 thin film

Antimony selenide (Sb2Se3) is regarded as one of the key alternative absorber materials for conventional thin film solar cells due to its excellent optical and electrical properties. Here, we proposed a Sb2Se3 thin film solar cell fabricated using a two-step process magnetron sputtering followed by a post-selenization treatment, which enabled us to optimize the best quality of both the Sb2Se3 thin film and the Sb2Se3/CdS heterojunction interface. By tuning the selenization parameters, a Sb2Se3 thin film solar cell with high efficiency of 6.06% was achieved, the highest reported power conversion efficiency of sputtered Sb2Se3 planar heterojunction solar cells. Moreover, our device presented an outstanding open circuit voltage (VOC) of 494 mV which is superior to those reported Sb2Se3 solar cells. State and density of defects showed that proper selenization temperature could effectively passivate deep defects for the films and thus improve the device performance.

Co-sputtered Cu2ZnTi(S:Se)4 absorbers for thin film solar cells

Thin film solar cells are an exciting topic for low cost and high efficient solar cells. Owing to the high price of the indium metal in the fabrication of copper indium gallium diselenide (CIGS) solar cells, Cu2ZnSn(SSe)4 thin films are used as a new material to reduce the cost and increase the efficiency.As an alternative absorber material for solar cell production, Cu2ZnTi(S:Se)4 thin films were deposited by the co-sputtering method at various temperatures. During the deposition, Cu, ZnSe and Ti targets were used as metal sources. The Cu2ZnTi(S:Se)4 thin films were annealed in H2S:Ar (1:9) atmosphere. The morphological, structural and optical properties of Cu2ZnTi(S:Se)4 thin films was analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) Raman spectroscopy and UV–Vis–NIR spectrometer. It was seen that the thin films had good optical absorption till the infrared region and the band gap of the Cu2ZnTi(S:Se)4 thin films were smaller than the conventional Cu2ZnSnS4 thin films. Furthermore, fabrication of a solar cell with 1.96% power conversion efficiency was reported using a Cu2ZnTi(S:Se)4 thin film as a low cost absorber layer.

Characterization of evaporated tin sulfide and its application for hybrid solar cell

Tin sulfide (SnS) is a promising absorber material for photovoltaic cells, because of its optimum band gap, strong optical absorption, simple phase composition, earth-abundant and nontoxic constituents. However, this material is largely unexploited to date with only a handful of studies reporting SnS for photovoltaic application. We present systematic preparation of SnS thin films through thermal evaporation route and characterize phase composition of these films. We have observed that the films grown at the substrate temperature of 250 °C exhibit a single SnS phase, which could be alternative light absorber materials for photovoltaic devices fabrication. Hence, a solar conversion efficiency of 1.47% was obtained at standard one sun illumination using a planar device consisting of FTO/TiO2/SnS/P3HT/Au. The present findings offer novel directions for achieving high-efficiency solid-state solar cells by hybridization of inorganic-organic light harvesters and hole transporters.

Review of Recent Progress in Antimony Chalcogenide‐Based Solar Cells: Materials and Devices

Antimony chalcogenides such as Sb2S3, Sb2Se3, and Sb2(SxSe1−x)3 have emerged as very promising alternative solar absorber materials due to their high stability, abundant elemental storage, nontoxicity, low‐cost, suitable tunable bandgap, and high absorption coefficient. Remarkable achievements have been made in antimony chalcogenide solar cells in the past few decades, with the power conversion efficiency (PCE) currently reaching 9.2%, which is close to the PCE level required for industrial applications. To facilitate the realization of highly efficient antimony chalcogenide solar cells in the future, a comprehensive review of antimony chalcogenide‐based materials and photovoltaic devices is presented. First, the fundamental physical properties and preparation methods of antimony chalcogenide‐based materials are outlined, and then, notable recent developments in antimony chalcogenide‐based photovoltaic devices with various architectures are highlighted. Finally, the most prominent limitations are described, and approaches to achieving remarkable advances in antimony chalcogenide solar cells in the future are provided.

Structural, electronic and optical properties of pulsed laser deposited Cu2SnS3 photo absorber thin films: A combined experimental and computational study

Pulsed laser deposited thin films of Cu2SnS3 (CTS) are characterized for the structural, electronic and optical properties using X-ray diffraction, Raman, UV–Vis-NIR spectroscopy, scanning electron microscopic techniques, and density functional theory. It is observed that thin-film samples annealed at low temperature have a metastable tetragonal structure, whereas the films annealed at 450 °C have a predominant stable monoclinic phase. A direct band gap of 1.1 eV, measured from the transmittance spectra, in close agreement with the theoretical band gap value of 0.89 eV obtained from density functional theory calculations. Optical properties reveal that CTS has a large absorption coefficient ~0.5 × 104 cm−1 at 1.5 eV which is comparable to other CuS based materials like CuInS2 and Cu2ZnSnS4. The direct band gap and large absorption coefficient make CTS as one of the potential alternative absorber materials for thin-film solar cell applications.

Electromagnetic Characteristics Measurement of Organic Material Absorber

Electro Magnetic Compatibility (EMC) Chamber requires high performance absorber material to assure the quality of EMC chamber related to Radio Frequency (RF) shielding effectiveness of the corresponding chamber. RF shielding effectiveness is measured following EN 50147-1 testing method. EMC laboratory of BPPT (Indonesian Agency for the Assessment and Application of Technology uses polyurethane absorber material which absorbs the carbon-neoprene mixture to maintain consistent RF performance over a broad frequency band, especially in the frequency range of CISPR 22 radiated emission test between 30 MHz to 6 GHz, limits in CISPR 22 (Information technology equipment-radio disturbance characteristics-limits and methods of measurement). This paper proposes alternative absorber materials based on organic materials: rice husk, coconut husk, cotton and sawn wood crumbs. In the early phase of this research, the frequency under consideration are 900 MHz and 1800 MHz. These frequencies are mostly used by mobile phone devices, therefore at this phase the resulted organic material absorber may be used for alternative mobile phone casing before to be used as absorber material for EMC laboratory in a broader frequency band. The organic materials are produced by mixing them with cement, carbon, and resin. Free space testing method is used in the measurements. Results has shown a mixture of 50% coconut husk with resin absorb the most radiated emission in 900 MHz, while 30% of coconut husk will absorb the most radiated emission in 1800 MHz.

Construction of self-assembled vertical nanoflakes on CZTSSe thin films

Cu2ZnSn(S, Se)4 (CZTSSe) is a promising alternative absorber material to achieve high power conversion efficiencies, besides its property of involving low-cost and earth-abundant elements when compared to Cu(In, Ga)Se2 (CIGS) and cadmium telluride (CdTe), to be used in solar cell technology. In this study, a novel fabrication technique was developed by utilizing RF sputtering deposition of CZTSSe thin films having a surface decorated with self-assembled nanoflakes. The formation of nanoflakes was investigated by detailed spectroscopic method of analysis in the effect of each stacked layer deposition in an optimized sequence and the size of nanoflakes by an accurate control of sputtering process including film thickness. Moreover, the effects of substrate temperature on the formation of nanoflakes on the film surface were discussed at a fixed deposition route. One of the main advantages arising from the film surface with self-assembled nanoflakes is the efficient light trapping which decreases the surface reflectance. As a result of the detailed production and characterization studies, it was observed that there was a possibility of repeatable and controllable fabrication sequence for the preparation of CZTSSe thin films with self-textured surfaces yielding low surface reflectance.

Promising Sb2(S,Se)3 Solar Cells with High Open Voltage by Application of a TiO2/CdS Double Buffer Layer

Sb2(S,Se)3 has gathered a lot of attention recently as a promising alternative absorber material. However, the efficiencies of Sb2(S,Se)3 devices are seriously restricted by the low open circuit voltage (Voc). In this work, Sb2(S,Se)3 devices equipped with a TiO2/CdS double buffer layer are prepared by a hydro‐thermal method, which aims to overcome the Voc deficit. The obtained average Voc of the devices is 785 mV and the champion efficiency of 5.73% is also achieved with a highest Voc = 792 mV, Jsc = 12.03 mA cm−2, FF = 60.9%. The improvement of Voc is benefited from the reduced band gap offset after application of the double buffer layer. The non‐encapsulated device could keep an average power conversion efficiency of 5.69% after being stored in ambient air over a month. This indicates the great potential of a double buffer layer in new chalcogenide photovoltaic devices.

Improved efficiency of Sb2Se3/CdS thin-film solar cells: The effect of low-temperature pre-annealing of the absorbers

Sb2Se3 is one of the alternative absorber materials for thin-film solar cells (TFSCs) comprising non-toxic and low-cost elements. The duration of pre-annealing at 100 °C prior to rapid thermal annealing (RTA) influenced the final morphology, crystallinity, and preferred orientation of thermally evaporated Sb2Se3. Pre-annealing for 40 min promoted the crystallization of pure Sb2Se3 phase following RTA; however, a long pre-annealing time such as 100 min rendered morphology similar to that of the reference absorber that was not pre-annealed, as ascertained by detailed scanning electron microscopy, X-ray diffraction, and Raman spectroscopic analyses. Furthermore, Sb2Se3/CdS TFSCs were fabricated with Sb2Se3 pre-annealed for various durations. The highest efficiency of 1.47% was achieved for the optimized 40-min pre-annealed absorber, enabling a smooth current flow. Our results emphasize the detailed optimization of pre-annealing time for achieving efficient TFSCs.