•Solution-processed (hydrothermal) growth of Sb2S3 on Mo substrate.•Assessment of structural and morphological evolution of Sb2S3 growth via annealing.•Fabrication of substrate architecture Sb2S3 ...solar cell devices.•A power conversion efficiency of ~1.0% was achieved for optimized device.
The binary chalcogenide material antimony sulfide (Sb2S3) has attracted significant attention as a potential absorber material for photovoltaics (PVs) owing to its suitable bandgap of ~1.7 eV and other unique properties. However, only a few substrate-configured Sb2S3 thin-film solar cells (TFSCs) have been reported, and they demonstrated an extremely low power conversion efficiency (PCE, η < 2.5%) owing to the unfavorable (hk0) orientation of Sb2S3. In most studies, Sb2S3 absorber layers were grown through physical vapor deposition or high-vacuum methods. By contrast, we used a facile hydrothermal approach to deposit Sb2S3 thin films on molybdenum and investigated the effect of post-deposition annealing on the structure, orientation, and morphology of Sb2S3 thin films. Annealing at temperatures ranging from 0° to 350°C transformed the Sb2S3 thin films from nearly amorphous to polycrystalline with large, horizontally aligned plate-like grains. All the annealed Sb2S3 thin films were confirmed to have a preferred orientation along the (hk0) crystal direction. The fabricated substrate-configured TFSCs with SLG/Mo/Sb2S3/CdS/i-ZnO/Al-doped ZnO/Al configuration exhibited the highest PCE of ~1.0%. Further, over 95% of this initial efficiency was maintained after 90 days. We also addressed the underlying reasons for the low efficiency of Sb2S3 TFSCs to provide a pathway for improving the device performance in the future.
Background
Metformin an oral hypoglycemic has been widely used as a fist line of treatment of Type II Diabetes but in a very high dose 2–3 times a day and moreover suffers from a number of side ...effects like lactic acidosis, gastric discomfort, chest pain, allergic reactions being some of them. The present work was conducted with the aim of sustaining the release of metformin so as to decrease its side effects and also reduce its dosing frequency using a novel delivery system niosomes (non-ionic surfactant vesicles). Non-ionic surfactant vesicles of different surfactants were prepared using thin film hydration technique and were investigated for morphology, entrapment, in-vitro release, TEM (transmission electron microscopy) and physical stability. Optimized formulation was further studied for the effect of Surfactant concentration, DCP (Dicetyl phosphate), Surfactant: cholesterol ratio and volume of hydration. The release studies data was subjected to release kinetics models.
Results
The prepared vesicles were uniform and spherical in size. Optimized formulation MN3 entrapped the drug with 84.50±0.184 efficiency in the vesicles of the size 487.60±2.646 and showed the most sustained release of 73.89±0.126. Also it was resulted that 100 molar concentration of cholesterol and surfactant, Presence of DCP, equimolar ratio of span 60: cholesterol and 15 ml of volume of hydration were found to be optimum for miosome preparation.
Conclusions
The present work concluded metformin loaded niosomes to be effective in sustaining the drug release leading to decreased side effects and increased patient compliance.
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CIGS-based thin film solar cell (TFSC) technology is emerging as a promising contributor to the solar photovoltaic industry next to the presently leading Si-based technology. Although ...the theoretical limit of power conversion efficiency (PCE) is as high as 33.5%, the highest experimental PCE so far just exceeded 20% in the past several years. Therefore, significant efforts are still continuing for further performance enhancement of these cells. Considering that the buffer layer has been identified as one of the key factors, the efforts to replace state-of-the-art but toxic CdS buffer layer have yielded promising results. Several studies showed that the alternative buffer layers grown with environmentally benign materials could even produce a better performance than the CdS-based TFSCs. In this regard, atomic layer deposition (ALD) has been proved as one of the best techniques for depositing the alternative buffer layers. Several Zn-based ternary and few other binary (e.g. In2S3) compounds have been investigated to realize an optimum ALD-grown buffer layer. In the recent year, a record PCE of 23.35% was achieved using ALD-grown ZnMgO buffer layer along with chemical bath deposited Zn(O,S,OH) for CIGSSe TFSC. However, in general the ALD-grown buffer layers only could provide PCEs well below 20%. The article presents a comprehensive survey on rapid increase in PCE for several ALD-grown buffer layers during the early period followed by a trend of saturation. Finally, the article discusses the current challenges and future scopes/possibilities for the ALD-grown buffer layers as potential alternatives of CdS toward practical applications of CIGS TFSC.
Tin monosulfide (SnS) has promising properties as an absorber material for thin-film solar cells (TFSCs). SnS/CdS-based TFSCs have the following device structure: SLG/Mo/SnS/CdS/i-ZnO/AZO/Al. The ...optimization of thickness of intrinsic zinc oxide (i-ZnO) for SnS-absorber layers and its impact on SnS/CdS heterojunction TFSCs has been investigated at different thicknesses ranging from 39 nm to 73 nm. With the increase in thickness of i-ZnO from 39 nm to 45 nm, the overall performance improved. The highest PCE of 3.50% (with VOC of 0.334 V, JSC of 18.9 mA cm−2, and FF of 55.5%) was observed for 45 nm-thick i-ZnO layers. Upon a further increase in the i-ZnO thickness to 73 nm, the device performance deteriorated, indicating that the optimum thickness of the i-ZnO is 45 nm. The device performances were analyzed comprehensively for different i-ZnO thicknesses.
Optimization of the i-ZnO thickness for SnS/CdS TFSC shows that a ∼45 nm i-ZnO layer is suitable for efficient device performance. Display omitted
•Role of i-ZnO in planar heterojunction solar cells.•Effect of i-ZnO thickness on the performance of SnS thin-film solar cells.•Improving shunt resistance of devices by optimizing the i-ZnO thickness.
We simulated a tin selenide (SnSe) based solar cell device in a standard planar substrate configuration (glass/Mo/SnSe/CdS/i-ZnO/AZO/Al) using a Solar Cell Capacitance Simulator (SCAPS-1D) software ...to elucidate a path to higher power conversion efficiency (PCE). A baseline model for the device was simulated and established using the experimental results of our recent study on a 2.51% device. A stepwise fitting procedure observed a higher effective density of states in SnSe, along with a band offset of −0.11 eV for conduction between SnSe and CdS; these factors are responsible for limiting the open-circuit voltage (VOC). We optimized the buffer and absorber layer parameters to improve the working capabilities to achieve higher efficiency by improving VOC. In particular, the effects of carrier concentration, absorber–buffer interface recombination, absorber thickness, buffer layer thickness, and defect densities were studied and analyzed in detail via simulation. Interestingly, optimal absorber and buffer layer thicknesses of 1.2 μm and 60 nm were obtained for the baseline and simulated devices. Finally, a NiO back-surface field (BSF) layer was introduced, and its performance was evaluated. Significant improvements in VOC and fill factor (FF) were observed with implementing the NiO BSF layer at the SnSe/CdS interface. The optimal device without a BSF layer exhibited a maximum efficiency of 13.79% with a VOC of 0.590 V; a short-circuit current density (JSC) of 36.28 mA cm−2, and an FF of 64.33%. Finally, the highest PCE of 22.69% with a VOC of 0.818 V, JSC of 33.65 mA cm−2, and FF of 82.41% was observed after applying the BSF layer.
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•Simulation of SnSe/CdS-based solar cells using experimental results.•Role of NiO BSF in SnSe/CdS planar heterojunction solar cells.•Importance of VB and CB eDOS to enhance the solar cell performance.•Improvement in the fill factor and open-circuit voltage by introducing a NiO BSF layer.
•A Sb2Se3 based heterojunction solar cell is stimulated with the SCAPS software.•The tin sulfide (SnS) layer was applied as a back surface field (BSF) layer.•Severe open-circuit voltage (VOC) loss in ...the device was recovered with the BSF layer.•The device efficiency of 17.75% was achieved at an ultrathin absorber layer thickness of 700 nm.
Recently, Sb2Se3 based solar cells have shown severe open-circuit voltage (VOC) loss that results in low device efficiency. In the present work, a model of Sb2Se3 solar cell with tin sulfide (SnS) as a back surface field layer (BSF) layer was designed and investigated via a solar cell capacitance simulator (SCAPS)-1D simulation software. The influence of the ultrathin BSF layer was investigated as a function of Sb2Se3 absorber thickness, and the corresponding device performance was analyzed. Apart from this, the effect of high BSF layer thickness, doping concentration, interface defect density, and resistance were also examined. Applying the BSF layer decreased the valence band offset value, which eases the hole transport at the back interface. At the same time, the high electric field region generated at the back interface creates a barrier for the minority carriers. Synergistically, in the presence of the BSF layer, the carrier recombination current densities were found to be almost negligible. As a result, the introduction of the 10 nm thin BSF layer significantly improved the device's VOC and power conversion efficiency (PCE) from 0.416 to 0.603 V and 9.61 to 17.75%, respectively for the absorber layer thickness of 700 nm. The present simulation study performed with the full earth-abundant element-based low-cost materials may assist the photovoltaic community in combating the VOC loss and further improving the PCE of Sb2Se3 based solar cells.
The replacement of CdS buffer layer is desirable for the development of nontoxic, environmentally friendly kesterite thin‐film solar cells (TFSCs). Recently, several ternary compound semiconductors ...have been extensively investigated as an alternative buffer layer for Cd‐free TFSCs. Herein, the effectiveness of (NH4)2S treatment on the surface properties of the absorber, as well as the device performance of atomic layer deposited (ALD) Zn(O,S) buffer‐based CZTSSe solar cells, has been investigated. X‐ray photoelectron spectroscopy (XPS) results showed that the elemental compositions of CZTSSe surface were significantly influenced by (NH4)2S treatment, whereas the surface morphologies of the CZTSSe‐absorber layers remained unaffected. The XPS results further suggested that the (NH4)2S solution treatment substantially removed the native oxide layer from the CTZSSe absorber surface. The fabricated CZTSSe/Zn(O,S) device without (NH4)2S treatment displayed an initial cell efficiency of 7.46%. The energy conversion efficiency increased significantly to 9.82% after the (NH4)2S treatment of absorber layers for an optimum duration of 1 min; to the best of our knowledge, this is the highest efficiency achieved to date for Zn(O,S) buffer‐based kesterite solar cells. The improved device performance is predominantly attributed to the pronounced increase in the fill factor (FF) of TFSCs resulting from the removal of oxides/hydroxides from the CZTSSe surface and passivation of absorber surface with sulfur species. However, increasing the treatment duration to 3 or 5 min resulted in the deterioration of cell efficiency, primarily due to the progressive degradation in the FF of the device. This study demonstrates a plausible route to improve the performance of Zn(O,S) buffer layer‐based kesterite solar cells through a simple surface treatment of the absorber layers using (NH4)2S solution.
A power conversion efficiency of 9.82% is achieved for atomic layer deposited Zn(O,S) buffer layer‐based CZTSSe solar cells through a simple surface treatment of the absorber layers using (NH4)2S solution.
Substrate specific differential growth gradient of π-SnS.
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•Differential nucleation and growth gradient of π-SnS are examined on substrates.•Optical properties vary due to compressive ...strain during thin-film deposition.•UPS reveals EVBM and ECBM as 4.48 and 2.78 eV for π-SnS.•Solar-cell device with substrate configuration exhibits efficiency of ~ 0.12%
Thin-films and nanomaterials with asymmetrical centers are widely used, and a representative example is π-SnS. The cubic phase of SnS is a “thermodynamic metastable” polymorph of SnS that has not been investigated extensively. Maintaining the stability of π-SnS intact and device fabrication are challenging owing to the lack of proper understanding of the nucleation and growth properties. We report a substrate-specific differential growth attribute of π-SnS based on the chemical deposition route. We evaluated the optical properties and band structure of π-SnS and achieved an efficiency of ~ 0.12% for a preliminary thin-film solar cell device.
The present study demonstrates that precursor passivation is an effective approach for improving the crystallization process and controlling the detrimental defect density in high-efficiency Cu
...ZnSn(S,Se)
(CZTSSe) thin films. It is achieved by applying the atomic layer deposition (ALD) of the tin oxide (ALD-SnO
) capping layer onto the precursor (Cu-Zn-Sn) thin films. The ALD-SnO
capping layer was observed to facilitate the homogeneous growth of crystalline grains and mitigate defects prior to sulfo-selenization in CZTSSe thin films. Particularly, the Cu
and Sn
defects and deep defects associated with Sn were effectively mitigated due to the reduction of Sn
and the increase in Sn
levels in the kesterite CZTSSe film after introducing ALD-SnO
on the precursor films. Subsequently, devices integrating the ALD-SnO
layer exhibited significantly reduced recombination and efficient charge transport at the heterojunction interface and within the bulk CZTSSe absorber bulk properties. Finally, the CZTSSe device showed improved power conversion efficiency (PCE) from 8.46% to 10.1%. The incorporation of ALD-SnO
revealed reduced defect sites, grain boundaries, and surface roughness, improving the performance. This study offers a systematic examination of the correlation between the incorporation of the ALD-SnO
layer and the improved PCE of CZTSSe thin film solar cells (TFSCs), in addition to innovative approaches for improving absorber quality and defect control to advance the performance of kesterite CZTSSe devices.
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