Absorber Layer Research Articles

Printing Perovskite Solar Cells in Ambient Air: A Review

AbstractThe demand for cost‐effective and rapid processing of large‐area thin films in the photovoltaic industry has recently driven significant research interest. In this context, among the various approaches explored, printing devices, particularly perovskite solar cells (PSCs), have garnered considerable attention due to their potential for scalability and cost efficiency. Besides, solution printing is widely recognized as an appealing strategy for large‐area, cost‐effective, and high‐throughput production of PSCs. However, while substantial progress has been made in this process, challenges related to stability, uniformity, and scalability remain to be addressed. This review critically examines the key printing techniques and substrates employed in PSC fabrication. Then, given the significance of ambient air printing for industrial applications, fundamental challenges associated with achieving ambient air production of PSCs are discussed in detail. Moreover, the formulation strategies of perovskite ink in printing technologies are thoroughly explored, considering its crucial role in determining the performance and stability of printed PSCs. Finally, the printing process for various components of PSCs, including the perovskite absorber layer, charge transport layers (CTLs), and electrodes, is meticulously analyzed, highlighting current achievements and remaining hurdles.

Filtered spectrum modeling of high-performance perovskite tandem solar cells: Tailoring absorber properties and electron/hole transport layers for 31.55 % efficiency

In this study, the perovskite tandem solar cell (TPSC) has been accomplished using SCAPS-1D. The present study focuses on comprehensive exploration and detailed optimization using various strategies constructing a tandem device. To calculate high photovoltaic power conversion efficiency (PCE), the numerical analysis has been carried out for a wide-bandgap halide (WBH) FA0.75Cs0·25Pb(I0·8Br0.2)3 of bandgap 1.67eV and a Pb–Sn based narrow-bandgap halide (NBH) FA0.7MA0.3Pb0·5Sn0·5I3 of bandgap 1.22eV as absorber layer in top-cell (TCELL) and bottom-cell (BCELL) respectively. The WBH has huge potential as a front light absorber and the NBH based BCELL provides stability and high performance by accepting high and low energy photons respectively. This method mitigates thermalization and non-absorbed photon loss which results in the growth in PCE. The proposed work demonstrates the impact of active-layer thickness along with defect density on the solar-cell parameters. It has been observed that defect density is low for the optimal performance. An investigation for various electron transport medium (ETMs) and hole transport medium (HTMs) has been done to secure an optimum performing TCELL as well as BCELL. Using filtered-spectrum study along with current-matching method, every PV metric parameter has been analyzed after their deployment into tandem configuration. The numerical investigation has shown promising photovoltaic parameters with aa high open circuit voltage (VOC) of 2.33 V, a short circuit current density (JSC) of 17.07 mA/cm2, a fill factor (FF) of 79.34 % and PCE of 31.55 % in tandem configuration.

Solar thermal applications of graphene-based block-ring resonator solar absorber using TiC–W materials

Solar absorbers enable the use of solar energy, a renewable and plentiful resource, minimizing reliance on finite fossil fuels and contributing to sustainable energy practices. The solar absorber that is studied here has an average absorptance of 96.85 % with a simple design and inexpensive materials. This design has two layers of resonator and active layer Block Ring Base Solar Absorber (BRBSA) structure. This study employs tungsten (W) as a resonator and titanium carbide (TiC) as a dielectric layer. The absorption spans from 100 to 3200 nm, with an average absorption exceeding 94 % across the entire structure. Notably, over 97 % of absorption occurs within the range of 210–710 nm, and the highest absorption, reaching 99.9 %, is observed in the wavelength range of 1510–1650 nm. The structure demonstrates high absorption rates across various regions, including 95.85 % in the UV region, 97.89 % in the visible, 95.73 % in the near-infrared, 95.87 % in the mid-infrared, and 89.56 % in the far-infrared region. After analyzing various potential variations of the proposed structure, an optimal design was identified. The parametric study was conducted to determine the optimal physical properties. Additionally, the electric field intensity analysis confirmed the proposed structure's broadband and constant absorption response. This Block Ring Base Solar Absorber has various uses, including solar drying systems, cookers, vaporizers, and warmers.

Investigations of optical and thermal properties of surface layers of Cd1−xBexTe samples by the photoacoustic method

The work presents the results of a research on the photoacoustic spectra of thin surface layers of Cd1−xBexTe crystals formed by grinding and polishing their surfaces. As a result of matching the theoretical and experimental photoacoustic spectra, thermal and optical parameters of these layers were determined. Thermal parameters of the surface layers, such as thermal conductivity and thermal diffusivity, turned out to be much worse than the analogous parameters of the substrate. The increase in the optical absorption of surface layers for photon energies below Eg was also determined. Eg was also determined.

Effect of Base Type Variation on Physicochemical Properties of Ambon Banana Peel (Musa Paradisiaca L) Methanol Extract Nanoemulsions Ointment

Ambon banana peel (Musa Paradisiaca L) contains flavonoids, tannins, terpenoids and saponins which have potential to be in the wound healing process. One of topical preparations suitable for wound healing is ointment. The ointment base can affect the release of active substances and absorption in the skin layers, since the release of the drug from its base is an important factor in the success of therapy. The aim of this study was to analyze the effect of base type variations on the physicochemical properties of ointments from banana peel methanol extract nanoemulsions. Ambon banana peel extract was obtained by maceration using methanol solvent and made in the form of a nanoemulsion. Ambon banana peel extract nanoemulsion is then added to the ointment preparation with water-soluble, absorption and hydrocarbon base types. Ointments with variations in base types were observed for physicochemical properties including organoleptic, homogeneity, viscosity, pH and spreadability. The data obtained were analyzed statistically using One Way ANOVA. The results showed that variations in base type affected on organoleptic appearance, viscosity and spreadability but had no effect on the pH value and homogeneity. The absorption base produces a formula that meets the requirements for ointment preparations.

Hydrothermal synthesis of kesterite CZTSSe nanoparticles for highly efficient thin film

CZTSSe kesterite nanoparticles have been investigated for the efficient. The hydrothermal method has been used to prepare the material. The various characterization like X-ray diffraction (XRD), Raman scattering, Scanning Electron Microscopy (SEM) for (UV–Vis) ultraviolet–visible spectrophotometry and (EDS) energy-dispersive X-ray spectroscopy and of the prepared nano particles have been studied. Furthermore, numerical analysis of the synthesized material has also been investigated to optimize the performance for more characterization at the device level. For the optimization purpose, we have modelled a device structure of the hybrid buffer layer and optimized its physical parameters for the efficient. Theoretical efficiency is found to be 18.46 % for the prepared model. The results of this study show that Cu2ZnSn (S, Se)4 could be used as an absorbent layer for efficient solar cell.

Trenched microwave resonator integrated with porous PDMS for detection and classification of VOCs with enhanced performance

Microwave resonators combined with polymer absorption layers are widely used in volatile organic compound (VOC) detection based on their variable resonant frequencies. However, the response time is limited due to the polymer’s slow volumetric absorption of VOC molecules. By constructing a porous structure in Polydimethylsiloxane (PDMS), resulting in reduced the response time to as short as 71.1%. To mitigate the sensitivity decline caused by the porous PDMS, a trenched-substrate complementary split-ring resonator (CSRR) is proposed for enhancing the interaction between the electromagnetic fields (EMFs) and the porous PDMS with VOCs. The removal of the substrate beneath CSRR’s sensing region enhances the effective EMF, increasing frequency and amplitude sensitivities up to 175.5% and 137.8%, respectively. Responses to four common VOCs by the sensor show a maximum sensitivity of 217 Hz/ppm and a minimum limit of detection of 295 ppm. Additionally, resonant parameters and extracted lumped parameters are utilized to establish two decision-tree-based VOC classification models, achieving high accuracies of 98.71% and 99.59%, respectively. And the latter one fully utilizing responses throughout the swept band, proves superior in identifying similar substances. This sensor technology helps promote the sensitive detection and accurate classification of diverse VOCs.

Numerical modelling of CuBi2O4 thin film solar cells with SCAPS-1D: Bridging the gap ideal and non-ideal conditions

Several simulation studies have been conducted in copper bismuth oxide (CuBi2O4) based solar cells (SCs) using SCAPS-1D simulator, demonstrating a high photoconversion efficiency (PCE) of up to 33 % under ideal conditions. The introduction of non-ideal conditions such as resistive losses, optical, and recombination losses could provide the actual performance of the SCs. In this letter, we applied all nonideal conditions to the SCs structure consisting of Mo/CuBi2O4/TiO2/ITO/Al with varied thicknesses of absorber layer of CuBi2O4 from 50 nm to 2 µm and evaluated the photovoltaic (PV) parameters and PCE of SCs. Under ideal conditions, cells exhibited a PCE of 31.23 % and 3.55 % with an absorber layer thickness of 2000 nm and 50 nm, respectively. The introduction of nonideal conditions with an absorber layer thickness of 50 nm, exhibited a drastic reduction of PCE from 3.55 to 0.46 % and other PV parameters such as open circuit voltage (Voc) from 1.19 to 1.04 V, short circuit current density (Jsc) from 4.27 to 0.77 mA/cm2, and fill factor (FF) from 69.40 to 56.42 %. The increase in thickness of the absorber layer further to 2000 nm did not improve the PCE of SCs.

Numerical simulation of a highly efficient perovskite solar cell based on FeSi2 photoactive layer

AbstractThe primary aim of this work is to investigate the use iron di‐silicide (FeSi2) as a photoactive layer in order to achieve superior performance in the solar cell architecture—ITO/TiO2/FeSi2/CuSCN/Ni. The optimum thickness of the absorber layer was found to be 1000 nm, which gave optimal properties of the proposed cell—a short‐circuit current density (Jsc) of 51.41 mAm−2, an open‐circuit voltage (Voc) of 0.93 V, a fill factor (FF) of 77.99%, and power conversion efficiency (PCE) of 37.17%. The introduction of an ultrathin interfacial layer between the electron transport layer (ETL), the perovskite interface, and the hole transport layer (HTL) enhanced the electrical output of the proposed solar cell. The Jsc increased to 51.86 mAcm−2, Voc rose to 0.97 V, while FF and PCE increased to 82.86% and 41.84%, respectively. Accordingly, the proposed cell architecture is promising and can be introduced into the manufacturing workflow for commercial applications. Moreover, because of its exceptional photon absorption capabilities, FeSi2 is a potentially excellent photoactive material for solar cell fabrication. The detailed findings of this study have therefore indicated that high‐performance FeSi2‐based solar can be achieved in future.

Numerical Optimization of Thickness and Optical Band Gap of Absorber and Buffer Layers in Earth-Abundant Cu2ZnSnS4 Thin-Film Solar Cells

Numerical Optimization of Thickness and Optical Band Gap of Absorber and Buffer Layers in Earth-Abundant Cu2ZnSnS4 Thin-Film Solar Cells

Investigating the potential of WO3 and WS2 as Cd-free buffer layers in Sb2Se3-Based thin-film solar cells: A numerical study with SCAPS-1D software

In this numerical study, the performance of thin-film solar cells (TFSCs) based on Sb2Se3 with WO3 and WS2 materials as Cd-free buffer layers was investigated using SCAPS-1D software. WO3 and WS2 were chosen for their suitable band gaps, good electrical conductivity, and optical transparency. The proposed solar cell structures, Au/Sb2Se3/WO3/ITO and Au/Sb2Se3/WS2/ITO were theoretically examined, considering various factors such as conduction band offset, absorber and buffer layer thickness, doping concentrations, series and shunt resistances, temperature, activation energy, and C–V characteristic. The conduction band offset at the absorber/buffer interface showed spike-like configurations, with values of 0.38 eV and 0.23 eV for the WO3 and WS2 buffer layers, respectively. The optimized thickness for the absorber layer in both structures was 1 μm, while for WO3 and WS2 buffer layers, it was 0.1 μm and 0.05 μm, respectively. The optimized acceptor and donor doping concentrations were 1 × 1016 cm−3 and 1 × 1018 cm−3, respectively. The efficiency of the proposed photovoltaic devices was found to be 9.538 % (with Voc = 0.561 V, Jsc = 30.856 mA/cm2, FF = 55.84 %) and 10.151 % (with Voc = 0.558 V, Jsc = 29.189 mA/cm2, FF = 62.34 %) for structures with WO3 and WS2 buffer layers, respectively. These results suggest that using non-toxic materials like WO3 and WS2 as buffer layers can be an efficient and environmentally friendly alternative to toxic CdS for fabricating cost-effective and highly efficient Sb2Se3-based TFSCs.

Short-Wave Infrared Colloidal QD Photodetector with Nanosecond Response Times Enabled by Ultrathin Absorber Layers.

Ultrafast short-wavelength infrared (SWIR) photodetection is of great interest for emerging automated vision and spatial mapping technologies. Colloidal quantum dots (QDs) stand out for SWIR photodetection compared to epitaxial (In,Ga)As or (Hg,Cd)Te semiconductors by their combining a size-tunable bandgap and a suitability for cost-effective, solution-based processing. However, achieving ultrafast, nanosecond-level response time has remained an outstanding challenge for QD-based SWIR photodiodes (QDPDs). Here, record 4ns response time in PbS-based QDPDs that operate at SWIR wavelengths is reported, a result reaching the requirement of SWIR light detection and ranging based on colloidal QDs. These ultrafast QDPDs combine a thin active layer to reduce the carrier transport time and a small area to inhibit slow capacitive discharging. By implementing a concentration gradient ligand exchange method, high-quality p-n junctions are fabricated in these ultrathin QDPDs. Moreover, these ultrathin QDPDs attain an external quantum efficiency of 42% at 1330nm, due to a 2.5-fold enhanced light absorption through the formation of a Fabry-Perot cavity within the QDPD and the highly efficient extraction (98%) of photogenerated charge carriers. Based on these results, it is estimated that a further increase of the charge-carrier mobility can lead to PbS QDPDs with sub-nanosecond response time.

Towards the fabrication of flexible thin film CdTe solar cells: The significance of substrate surfaces

Thin film CdTe solar cells have been recognized as reliable alternative for the manufacture of cheap photovoltaic solar cells of the future, due to its excellent absorber characteristics and simple, low-cost manufacturability. However, for the attainment of higher cell performances, additional studies are needed to increase cell efficiency through further development of better quality films and new fabrication processes. In the substrate-structured CdTe thin film solar cells, the CdTe absorber layer is deposited directly onto the substrate or through a back contact layer. But the quality of deposited film is believed to depend on the type and smoothness of the substrate. In this work CdTe was deposited on different substrates by RF sputtering and the effects on the deposited films were studied in terms of their structural and morphological forms. The substrates used were: pure molybdenum sheets (Mo), molybdenum-sputtered on molybdenum (Mo/Mo), molybdenum-sputtered polyimide (PI/Mo) and molybdenum-sputtered glass (glass/Mo). The characterization tools used included XRD, SEM and AFM. The results showed that all surfaces produced uniform, compact and pinhole-free films; however, those on smoother surfaces produced larger as-deposited grain sizes of up to1.7μm as against 1.3 for rougher surfaces. Non-uniformities such as overgrowth and voids were observed, but only films on PI showed evidence of cracking and peel-offs.

Maximizing photovoltaic performance of all-inorganic perovskite CsSnI3-xBrx solar cells through bandgap grading and material design

In the modern era of technology, worldwide paradigms have been shifted toward the utilization of green energy. Sun energy is the most astonishing eco-friendly resource of energy and can be harnessed with the help of photovoltaic cells. Hybrid (Organic-Inorganic) perovskite solar cells (PSCs) are emerged with incredible photovoltaic (PV) performance. Nevertheless, a significant challenge lies in their lower stability under diverse environmental conditions. To deal with this challenge, all inorganic cesium-based PSC has been studied and analyzed, results improved stability in comparison to hybrid PSC. However, the noxious nature of lead is deleterious to the environment. So, this work primarily aimed, to study lead-free all inorganic tin-based perovskite compound CsSnI3-xBrx, as the main light absorber layer. Further, to elevate the PV performance of PSC, bandgap grading is performed on CsSnI3-xBrx by varying bromide concentration x from 0 to 3. Bandgap grading encourages the absorption of a wide range of the light spectrum, by modulating bandgap (Eg) / affinity(χ) through the distance of the CsSnI3-xBrx layer. Additionally, it enhances light-generated charge carrier separation and collection by end electrodes. In this work, two different strategies have been adopted, linear and parabolic. During linear grading, the impact of variation in x (0 to 3) has been analyzed over the thickness 50–––500 nm in 10 linear steps for CsSnI3-xBrx. The highest PCE fetched from linearly graded layered FTO / CeO2 / CsSnI3-xBrx / CFTS / Gold PSC is 21.68 %. Similarly, in the parabolic graded absorber layer, the influence of change in the bowing factor (0 to 1), has been analyzed relative to different values of x (0 to 3). With improvement in PV performance, the maximum PCE delivered by parabolic-graded PSC is 23.61 %. Additionally, this work extends to check the compatibility of distinct electron transport layers (ETLs) and hole transport layers (HTLs). Upon analysis, it has been found that the best PV performance was obtained while selecting SnO2 / PEDOT as ETL / HTL respectively.

Point-junction and alkali-assisted surface selenium diffusion: Unveiling a two-step method for enhancing the efficiency of VTD-SnS thin-film solar cells

Surface and interface engineering in thin-film solar cells (TFSCs) is vital for optimizing charge carrier dynamics, reducing recombination, enhancing material properties, and ultimately improving efficiency and overall performance. In this study, e-beam evaporation was used to deposit selenium (Se) onto tin sulfide (SnS) absorber layers with a thickness of 10 nm to 50 nm. The Se layer optimization was validated using various characterization techniques, which confirmed the formation of micro-sized openings via Se droplet deposition. This Se passivation-plus-local opening geometry plays a crucial role in forming point junctions with the n-type CdS during cell fabrication, presenting a novel approach in state-of-the-art technology. The results revealed a significant enhancement in the conversion efficiency of the SLG/Mo/SnS/Se/CdS/i-ZnO/AZO/Al device to 3.01 % (VOC = 0.326 V, JSC = 20.21 mA cm−2, and FF = 0.45) with 30 nm Se layer deposition. Furthermore, a 30 nm-thick NaF-assisted Se layer was deposited to improve device performance. The diffusion of both Se and Na into the SnS substrate was validated using XRD, SEM, EDS, AFM, and XPS. The power conversion efficiency (PCE) of the SLG/Mo/SnSSe-NaF/CdS/i-ZnO/AZO device was further enhanced to 3.70 % (VOC = 0.340 V, JSC = 22.56 mA cm−2, and FF = 0.48). This enhancement is attributed to the creation of localized junctions via Se surface passivation, and the concurrent SnSSe formation induces band gap tuning and increases the grain size, contributing to additional PCE improvement during Na-assisted Se diffusion.

Significant enhancement of optical absorption of graphene inside a metallic optical microcavity

The increase in the optical absorption of the graphene layers above the value of 2.3% of the bare layer in vacuum is of great interest for application in opto-electronics. A monolayer graphene sheet embedded in a stacked dielectric layers has been shown to reach an absorption up to 50%. Here, we theoretically show that the absorption could be significantly enhanced to greater than 50% via boosting the environmental permeability by using an empty optical cavity. This enhancement is nearly independent on the structure of the environment around the graphene sheet, except for the dimensional parameters of the cavity. The obtained results are crucial for motional control of graphene sheets by an all-optical method.

Investigation of FABr treatment's potential for triple-cation multi-halide perovskite solar cells

In order to preserve the effectual potential of triple-cation coupled with multi-halide perovskites (PVTs), the phase-related conflict amongst different precursors have to be resolved. There arises the necessity of post-growth passivation treatments, especially using formamidinium bromide (FABr) upon such PVT films. In this research, a methodical comparison assessment is performed on triple-cation, multi-halide (CsFAMAPbIBr)-based PVT solar cells (PSCs) with and without FABr passivation using numerical study. A meticulous estimation of all the performance parameters of both PSCs were implemented in accordance with transformations in thickness, effective density, and acceptor density of the PVT absorber layer together with the charge transport layer thickness variations. The investigation revealed that the charge carrier generation rate remained the same after FABr passivation, however,the recombination rate was lowered by ∼ 32 % (from 7.27 × 1021 to 4.92 × 1021 cm-3s−1). The analysis discerned that at minimum valence band effective density of PVT absorber: 1 × 1017 cm−3, FABr-treated CsFAMAPbIBr-based PSC ensures the highest power conversion efficiency of 24.62 % against its un-passivated correspondent of 22.25 %. Further, this investigation imparts the remarkableness of FABr passivation treatment in regulating the overall performance of triple-cation and multi-halide-based PSCs.

Complementary absorption effect to improve the optical efficiency of dual-absorption-layered PSCs

By taking advantage of the complementary absorption effect of germanium (Ge) and perovskite, a novel perovskite solar cell (PSC) was proposed by stacking Ge and perovskite thin films to serve as the dual absorption layer. Its absorption spectra and photocurrent were calculated and optimized as a function of the thickness of Ge film by finite element method (FEM). Then, the optical efficiency was further boosted by embedding an array of Ge semi-ellipsoidal nanoparticles within the perovskite film. The predicted maximum photocurrent is revealed to reach 45.72mA/cm2, which is 2.55 times larger than that of planar referenced PSC. Besides the complementary absorption effect, the localized surface plasmon resonance (LSPR) of Ge nanoparticles and the grating effects of Ge nanoparticle array are revealed to contribute to the obtained Jsc improvement. The present work is insightful for future design and applications of PSCs by introducing Ge thin film and Ge nanoparticles.

Molecular simulation of the regulation mechanism of surfactant on microscopic chemical wetting of coal

To explore the influence mechanism of surfactants on the wettability of coal, elemental analysis, Fourier-transform infrared spectroscopy, 13C nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy were applied to characterize the chemical structure of coal before and after modification with solutions having different concentrations of sodium dodecyl sulfate. Macromolecular models of four different coal samples before and after modification were constructed, and the mechanism of the change in the chemical structure of the coal before and after modification on its wettability was then studied with molecular dynamics (MD) simulations. The molecular formulas of the four coal samples were determined to be C160H114O34N2S, C203H144O44N3S, C196H137O42N3S, and C242H171O56N3S. Aromatic carbon accounts for a relatively high proportion of these formulas, mainly in the form of benzene rings and naphthalene. The ratios of aromatic bridge carbons to pericarbons are 0.3, 0.23, 0.21, and 0.22, respectively. Nitrogen (N) and sulfur (S) are present as pyrrole nitrogen and thiol thiophenol, respectively. MD simulations show that compared with the original coal sample, the thickness of the absorption layer between the modified coal and water molecules increases, and the interaction energy is enhanced. The maximum electrostatic potential of the surface of coal molecules in the four systems (−0.07826, −0.07915, −0.08511, and −0.10711 a.u.) is concentrated around the oxygenated functional groups. After the modification, the distribution of oxygenated functional groups is more extensive, and the content of water molecules adsorbed on the surface of the coal increases because of static electricity, which promotes the wettability of the coal. This research reveals the microscopic wetting mechanism of coal dust at the molecular level and provides a research path that offers important guidance for the reduction of coal dust that is generated during mining.

Preconcentrating extractive polymeric network in paper-based sensing of copper

The concept of using an extractive polymeric sensing network on a paper-based substrate for the pretreatment of samples in the colorimetric analysis of heavy metals is demonstrated with the determination of Cu2+ in aqueous samples. The newly developed paper-based device combines the advantages of both liquid–liquid extraction-based separation and the analytical capabilities of microfluidic paper-based analytical devices (μPADs). The preconcentrating extractive polymeric network composed of 53.5 wt% poly(vinyl chloride) (PVC), 45 wt% extractant (di-(2-ethylhexyl)phosphoric acid (D2EHPA)) and 1.5 wt% dye (1-(2′-pyridylazo)-2-naphthol (PAN)), coated on filter paper, shows good water-wicking properties, allowing the transmission of high sample volumes. This results in significant analyte preconcentration. The extractant (D2EHPA) selectively binds Fe3+ and Zn2+ which otherwise will compete with Cu2+ in its colour reaction with PAN at the chosen pH of 3.0. The device’s capacity to process higher sample volumes resulting in higher sensitivity is increased by the integration of several filter paper absorption layers. The optimized device is characterized by a limit of detection (LOD) for tap and environmental waters of 3.4 and 9.6 µg/L, respectively; stability of 51 days if stored in a refrigerator; and total analysis time (from sample insertion to colour detection) of less than 5 min.