Contact Silicon Research Articles

Hyaluronic Acid-Pluronic®F127-Laden Soft Contact Lenses for Corneal Epithelial Healing: In Vitro and In Vivo Studies.

Hyaluronic acid (HA) is widely used to treat various ocular diseases like dry eye syndrome, keratoconus, and other corneal epithelial injuries. The currently available eye drop solutions need frequent doses affecting the routine life style of patients. In this work, the silicone contact lens was designed to entrap HA and Pluronic®F127 to improve the wettability of the contact lens to treat various ocular diseases. The soaking method (HA-SM) was compared with the direct entrapment (DL-HA-PI) technique. The HA-Pluronic®F127-laden contact lenses (DL-HA-PI) showed acceptable optical transmittance with improved swelling (water content) properties. The in vitro release data showed high burst release with HA-SM contact lenses (12-36h), while DL-HA-PI contact lenses showed prolong release up to 96h. The in vivo release in the rabbit tear fluid showed high HA concentration (tear fluid) with DL-HA-PI contact lenses in comparison to the HA-SM contact lenses. The DL-HA-PI-3 batch with Pluronic®F127 showed more promising results in schirmer strip study in comparison to DL-HA-3 batch (without Pluronic®F127). The presence of Pluronic®F127 with HA showed high potential to improve hydration property of the contact lens. The corneal healing model showed reduction in the ocular inflammatory symptoms with DL-HA-PI-3 batch, thus demonstrating the potential of HA and Pluronic®F127 to be used in various ocular diseases.

Highly Transparent Covalent Mucin Coatings Improve the Wettability and Tribology of Hydrophobic Contact Lenses.

A stable, good coverage of the corneal tissue by the tear film is essential for protecting the eye. Contact lenses, however, constitute a foreign body that separates the tear film into two thinner layers, which are then more vulnerable toward disruption. This effect is even more pronounced if the contact lenses possess an insufficient surface wettability, which, in addition to friction, is suggested to be linked to discomfort and damage to the ocular surface. In this study, we establish covalent surface coatings with mucin macromolecules to overcome this issue for pure silicone contact lenses. This material class, which outperforms state-of-the-art silicone hydrogels in terms of oxygen permeability, is not yet used for commercial contact lens applications, which is due to its strongly hydrophobic surface characteristics. The applied process stably attaches a transparent mucin layer onto the contact lenses and thereby establishes hydrophilic surfaces that not only prevent lipid adsorption but also interact very well with liquid environments. Most importantly, however, we show that those mucin coatings are indeed able to prevent wear formation on corneal tissue that is subjected to the tribological stress applied by a contact lens. Our results open up great possibilities for a variety of hydrophobic materials that are, to date, not suitable for a contact lens application. Furthermore, the ability of mucin coatings to reduce wear in a tissue/synthetic material contact might be also beneficial for other biomedical applications.

Titanium Nitride Electron-Conductive Contact for Silicon Solar Cells By Radio Frequency Sputtering from a TiN Target.

Efficient and stable electron selective materials compatible with commercial production are essential to the fabrication of dopant-free silicon solar cells. In this work, we report an air-stable TiN (titanium nitride) polycrystalline film, deposited using radio frequency sputtering process, as an electron selective contact in silicon solar cells. TiN films deposited at 300 W and 1.5 mTorr exhibit a low contact resistivity of 2.0 mΩ·cm2. Furthermore, the main factors and mechanisms affecting the carrier selectivity properties are also explored. TiN layers as full area rear electron contacts in n-type silicon solar cells have been successfully implemented, even though TiN film contains some oxygen. This process yields a 17% increment in relative efficiency in comparison with reference devices (n-Si/Al contact). Hence, considering the low thermal budget, scalable technique, and low contact resistivity, the TiN layers can pave the way to fabricate high-efficiency selective contact silicon solar cells with a higher degree of reproducibility.

Development of High‐Efficiency n‐Type Front and Back Contact Passivated Emitter and Rear Locally Diffused Solar Cells Using Atmospheric Pressure Chemical Vapor Deposition of Phosphosilicate Glass and Laser Processing

Industrial bifacial n‐type front and back contact (nFAB) silicon solar cells, consisting of a boron‐doped p+ emitter and a phosphorus‐doped n+ back surface field (BSF), are known to give good bifaciality, high and stabilized efficiency. One possible approach to further enhance the cell efficiency is to convert conventional passivated emitter and rear totally diffused (PERT) into rear locally diffused (PERL) structure. Herein, bifacial nFAB PERT and PERL cells are fabricated by combining atmospheric pressure chemical vapor deposition (APCVD) of phosphosilicate glass (PSG) as doping source and laser processing. For PERL cells, two approaches are studied to locally form phosphorus‐doped BSF: 1) laser doping, and 2) laser ablation of a diffusion barrier layer. For ablation approach, an alkaline treatment is introduced immediately after laser process, which leads to the formation of locally textured BSF. Due to this locally textured contact, the resultant fill factor (FF) and series resistance (Rs) loss of the PERL cells are even less than that of the reference PERT cells. As a result, the champion cell of PERL shows a good efficiency of 21.3% with open‐circuit voltage (Voc) of 662 mV, short‐circuit current density (Jsc) of 39.6 mA cm−2, and a high FF of 81.1%.

Combined Optical-Electrical Optimization of Cd1-xZnxTe/Silicon Tandem Solar Cells.

Although the fundamental limits have been established for the single junction solar cells, tandem configurations are one of the promising approaches to surpass these limits. One of the candidates for the top cell absorber is CdTe, as the CdTe photovoltaic technology has significant advantages: stability, high performance, and relatively inexpensive. In addition, it is possible to tune the CdTe bandgap by introducing, for example, Zn into the composition, forming Cd1−xZnxTe alloys, which can fulfill the Shockley–Queisser limit design criteria for tandem devices. The interdigitated back contact (IBC) silicon solar cells presented record high efficiencies recently, making them an attractive candidate for the rear cell. In this work, we present a combined optical and electrical optimization of Cd1−xZnxTe/IBC Si tandem configurations. Optical and electrical loss mechanisms are addressed, and individual layers are optimized. Alternative electron transport layers and transparent conductive electrodes are discussed for maximizing the top cell and tandem efficiency.

Investigation of Sensitive Structures of Nanostructured Silicon – Melanin

The goal of this work is to study the current-voltage characteristics of structures of porous silicon – melanin and sensitivity of structures to glucose, to compare the characteristics between the samples obtained by different techniques. Object of study – structures of porous silicon – melanin. The subject of the study is the change of electrophysical parameters depending on the change in the analyte concentration. Organic-inorganic structures have recently attracted considerable interest in electronics due to the ability to create cheaper and simpler devices than traditional inorganic semiconductors. Melanin is an organic pigment that is present in many living organisms and has semiconductor properties. Melanin interacts with most biological substances, making it a promising material in the field of biosensors. Measuring glucose levels in the world today is very popular in the health and food sectors, so there is a constant need for easy-to-use and low-cost sensors. The purpose of this work was to investigate the heterojunction of melanin-porous silicon and the possibility of creating glucose sensors on such structures. For sample preparation metal-assisted chemical etching with three different types of metal nanoparticles (silver, copper, gold) was used. This technique allow formation of arrays of silicon nanowires with high aspect ratio. After porous silicon etching metal residuals were removed and thin layer of water-solube melanin was deposited at the surface and polymerized. Silver-based dot contacts was used for measurements. The I-V curves of the studied samples were measured in the work, such parameters as: resistance of structure, coefficient of rectification at contact of porous silicon – melanin, coefficient of rectification at contact of substrate – melanin, sensitivity to glucose were calculated. It was shown that I-V curves of both melanin/porous silicon and melanin/porous silicon/bulk silicon structures are diode-like with rectification factor at 5 V up to 80 for melanin/porous silicon heterojunction and up to 800 for melanin/porous silicon/bulk silicon structure. Resistor-like sencitive structures of melanin – nanostructured silicon are sensitive to glucose with a sensitivity coefficient of up to 1.83 mA /%. It was noticed that samples prepared with copper nanoparticles have opposite dependence (decreasing of current with increase of glucose concentration). No clear correlation was observed between the sensitivity, the rectifying properties and the technology of sample preparation, but the most stable results were obtained for structures made with silver nanoparticles.

The impacts of LPCVD wrap-around on the performance of n-type tunnel oxide passivated contact c-Si solar cell

In this paper, Tunnel Oxide Passivated Contact (TOPCon) silicon solar cells with the industrial area (244.32 cm2) are fabricated on N-type silicon substrates. Both the ultra-thin tunnel oxide layer and phosphorus doped polycrystalline silicon (polysilicon) thin film are prepared by the LPCVD system. The wrap-around of polysilicon is observed on the surface of borosilicate glass (BSG). The polysilicon wrap-around can form a leakage current path, thus degrades the shunt resistance of solar cells, and leads to the degradation of solar cell efficiency. Different methods are adopted to treat the polysilicon wrap-around and improve shunt resistance of solar cells. The experimental results indicate that a chemical etching method can effectively solve the problem of polysilicon wrap-around and improve the performance of solar cells. Finally, a conversion efficiency of 22.81% has been achieved by our bifacial TOPCon solar cells, with Voc of 702.6 mV, Jsc of 39.78 mA/cm2 and FF of 81.62%.

Multiple drug delivery from the drug-implants-laden silicone contact lens: Addressing the issue of burst drug release.

A fixed combination of bimatoprost/timolol eye drop solution is used to manage the elevated intra-ocular pressure in glaucoma patients, including individuals whose condition is poorly controlled by monotherapy. Eye drop solutions are generally given in high dose, due to poor ocular bioavailability. The high ocular dose of bimatoprost and timolol lead to hyperaemia and systemic cardiac side effects respectively. Here, we introduce multiple implant-laden contact lenses (IM) to passively deliver timolol, bimatoprost and hyaluronic acid at therapeutically relevant doses without high burst release. The drug-loaded implants were individually implanted in the outer periphery of the silicone contact lenses. Atomic force microscopy showed the smooth surface of the implant contact lens, as the implants were inside the contact lens matrix. The implant lens (IM) showed major loss of drugs [timolol=60.60%, bimatoprost=61.75% and HA=46.03%] during the monomer extraction and wet sterilization, while the option of dry radiation sterilization (IM-R lens) and hydration for 24h prior to use showed relatively lower loss of drugs [timolol=16.87%, bimatoprost=47.95% and HA=24.41%]. The in-vitro drugs release data of IM-R lens, showed sustained release for 72h, with low burst release in comparison to the soaked (SM) and direct drug-laden contact lenses (DL). The in vivo drug release data in the rabbit tear fluid showed sustained release using IM-R lens in comparison to the SM lens and eye drop therapy. The burst release with the IM-R lens was many folds reduced, which could bypass the side effects associated with multiple eye drop therapy. The in vivo pharmacodynamic study in the rabbit model showed peak and valley profile with multiple eye drop therapy, while IM-R lens showed prolong reduction in intra ocular pressure (IOP) for 120h. The study demonstrates the application of implantation technology to deliver multiple drug through contact lenses to treat glaucoma.

Toward High Solar Cell Efficiency with Low Material Usage: 15% Efficiency with 14 μm Polycrystalline Silicon on Glass

Liquid‐phase‐crystallized silicon (LPC‐Si) is a bottom‐up approach to creating solar cells with the potential to avoid material loss and energy usage in wafer slicing techniques. A desired thickness of silicon (5–40 μm) is crystallized with a line‐shaped energy source, which is a laser, herein. The first part reports the efforts to optimize amorphous silicon contact layers for better surface passivation. The second part covers laser firing on the electron contact. It enables a controllable trade‐off between charge collection and fill factor (FF) by creating a low resistance contact, while preserving a‐Si:H (i) passivation in other areas. Short‐circuit current density (JSC) is observed to be up to 33:1 mA cm−2, surpassing all previously reported values for this technology. Open‐circuit voltage (VOC) of up to 658 mV also exceeded every previous value published at a low bulk doping concentration (1 × 1016 cm−3). Laser firing reduced JSC by 0:6 mA cm−2 on average but improved the FF by 22.5% absolute on average, without any significant effect on VOC. Collectively, these efforts have helped in achieving a new in‐house record efficiency for LPC‐Si of 15.1% and show a potential to reach 16% efficiency in the near future with optimization of series resistance.

Investigation of anomalous behaviour in J-V and Suns-Voc characteristics of carrier-selective contact silicon solar cells

Process and configuration dependent carrier-selective Ag/ITO/MoOx/n-Si/LiFx/Al silicon solar cells having conversion efficiencies from 6.5% to 14.5% are investigated. Some of the cells’ anomalous characteristics in light J-V and Suns-VOC graphs are analysed by photo-induced capacitance-voltage (C-V), impedance spectroscopy (IS), and voltage- plus light-biased (white, blue and infrared) quantum efficiency (QE). Correlated analysis of cells revealed the physical origin of S-shape in light J-V and turnaround in Suns-VOC graphs. After air exposure of the MoOx film, the charge carrier accumulation at the front interface and inefficient transport through the MoOx layer have led to the anomalous features in light J-V and Suns-VOC graphs of the cell. This is reflected as an additional peak and arc in C-V and IS graphs, respectively. In the absence of the LiFx layer, the cell has shown the only turnaround in Suns-VOC graph due to the Schottky barrier. The IS analysis resolved carrier transport issues at the front junction and back contact of the cells with a distinguished response. The light-bias dependent QE analysis has confirmed the presence of carrier collection barrier at the MoOx/c-Si interface, and the Schottky contact at the back with a different response in EQE spectra.

Influence of Interfacial Oxides at TCO/Doped Si Thin Film Contacts on the Charge Carrier Transport of Passivating Contacts

Minimizing transport losses in novel solar cell concepts is often linked to improvements at the transparent conductive oxide (TCO)/doped silicon contact. A detailed understanding of the determining factors for an efficient transport at this heterojunction is essential, such as work function matching and efficient tunneling transport. In this article, we analyze the different TCO contact parameters experimentally and by numerical device simulations. We show that work function matching by using a proper interlayer [e.g., tungsten oxide (WO x )] can be an effective means to improve the fill factor of silicon heterojunction solar cells. However, we showcase that an improved work function matching achieved by changing the doping of a TCO interlayer can be superimposed by a less efficient tunneling transport, for e.g., due to an interfacial oxide. Furthermore, we show that for n-tunnel oxide passivating contacts, an unintentionally grown oxide at the TCO/poly-Si contact could be a possible explanation for recently observed transport losses.

26.7% Efficient 4-Terminal Perovskite–Silicon Tandem Solar Cell Composed of a High-Performance Semitransparent Perovskite Cell and a Doped Poly-Si/SiOxPassivating Contact Silicon Cell

The rapid rise in single-junction perovskite solar cell (PSC) efficiencies, tunable bandgap, and low-cost solution processability make PSCs an attractive candidate for tandems with Si bottom cells. However, the challenge is to fabricate a high-performance semitransparent perovskite top cell in combination with an appropriate silicon bottom cell with high response to long wavelength photons that are filtered through the perovskite top cell. Currently, semitransparent perovskite cells show much lower performance compared with their opaque counterparts, while high-performance silicon bottom cells, such as heterojunction with intrinsic thin layer and interdigitated back contact, may be too expensive to meet the cost and efficiency targets for commercial viability. Here, we demonstrate a 26.7% perovskite-Si four terminal (4T) tandem cell comprising a highly efficient 17.8% CsFAMAPbIBr semitransparent, 1.63-eV bandgap perovskite top cell, and a ≥22% efficiency n-type Si bottom cell fabricated with a conventional boron diffused emitter on the front and carrier selective n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> poly-Si/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> passivated contact on the rear. This is among the highest efficiency perovskite/Si 4T tandems published to date and represents the first report of the use of the high temperature-resistant single side n-tunnel oxide passivated contact Si cell in a 4T configuration.

Origin of the tunable carrier selectivity of atomic-layer-deposited TiOx nanolayers in crystalline silicon solar cells

Titanium oxide (TiOx) nanolayers grown by atomic layer deposition are investigated with respect to their application as carrier selective contacts for crystalline silicon (c-Si) solar cells. Although TiOx is known to act as an electron contact, in this work the selectivity of TiOx layers is found to be widely tunable from electron to hole selective depending on deposition conditions, post-deposition treatments, and work function of the metal electrode used. Using TiOx and an intrinsic hydrogenated amorphous silicon buffer layer, solar cell test structure exhibiting open-circuit voltages (Voc) as high as 720 and 650 mV are shown for electron and hole selective contacts, respectively. Surface photovoltage and capacitance-voltage measurements reveal that carrier selectivity is correlated with the amount of c-Si band bending induced by TiOx, which are governed not only by the effective work function difference at the Si/TiOx interface, but also by the negative fixed charge present in the TiOx layer. This new finding is in contrast to the previous model for carrier transport where selectivity is determined only by the asymmetric band offsets at the Si/contact interface. It highlights the influence of induced band bending to produce carrier depletion/inversion conditions, and the importance of its selectivity effect in a c-Si absorber.

Front contact optimization for rear-junction SHJ solar cells with ultra-thin n-type nanocrystalline silicon oxide

In this work, ultra-thin n-type hydrogenated nanocrystalline silicon oxide [(nc-SiOx:H (n)] film was used to replace amorphous silicon [a-Si:H (n)] as electron transport layer (ETL) in rear-junction silicon heterojunction (SHJ) solar cell to reduce front parasitic absorption. The contact resistivity between the transparent conductive oxide (TCO) and ultra-thin ETL interface plays an important role on the cell performance. A nanocrystalline silicon (nc-Si:H) contact or seed layer was introduced in the solar cell with ultra-thin nc-SiOx:H and the impact of the nc-Si:H thickness on the cell performance was investigated. To demonstrate scalability, bifacial solar cells with 10 nm ETL were fabricated on the M2 (244 cm2) wafer. The best cell performance is obtained by the solar cell with 5 nm nc-SiOx:H (n) and 5 nm nc-Si:H (n) contact layer and it exhibits open-circuit voltage (Voc) of 738 mV, fill factor (FF) of 80.4%, short-circuit current density (Jsc) of 39.0 mA/cm2 and power conversion efficiency (η) of 23.1% on M2 wafer. Compared to the one with nc-SiOx:H (n), an increase of 3%abs of FF and 0.5%abs of η and lower front contact resistivity is demonstrated for the solar cells with nc-Si:H (n) / nc-SiOx:H (n) double layer, which is caused by the lower energy barrier for electrons, according to the band diagram calculated by the AFORS-HET simulator. A simulation on the solar cell optical and electrical losses was done by the Quokka 3 simulator and shows much lower electrical transport loss and a bit higher front surface transmission loss for the one with double layer than nc-SiOx:H (n) single layer.

In Vitro and In Vivo Studies of Polyvinyl Pyrrolidone–Coated Sparfloxacin-Loaded Ring Contact Lens to Treat Conjunctivitis

Currently, conjunctivitis is treated by frequent high dose administration of sparfloxacin eye drop solution. However, the eye drops are inconvenient because of low bioavailability, short ocular drug residence time, and need of frequent instillation, which lead to patient noncompliance affecting the routine life style of patients. Silicone contact lenses can be used to sustain the release of sparfloxacin. However, the presence of sparfloxacin alters the optical and physical properties of the contact lens. To overcome the issues, a novel polyvinyl pyrrolidone (PVP)-coated sparfloxacin-laden ring contact lens was designed to provide sustained ocular drug delivery without altering the optical and swelling properties of contact lens. The ring was implanted within the periphery of the lens. Sparfloxacin was loaded by soaking (Sp-S), direct loading (Sp-L), and ring casting method (Sp-R). PVP (comfort agent) was coated on the surface of contact lens by novel short surface curing technique. The in vitro sparfloxacin release data of Sp-S (up to 12-36 h) and Sp-L batches (up to 12-24 h) showed high burst release, whereas Sp-R batch showed sustained release up to 36-48 h without significant (p > 0.05) alteration of the optical and swelling properties. All the batches showed sustained release of PVP up to 48 h. The in vivo release studies in the rabbit tear fluid showed improvement in the sparfloxacin [>MIC for Staphylococcus aureus] and PVP retention time in comparison to eye drop solution. The in vivo efficacy study in the S aureus-induced conjunctivitis showed improved healing effect with the single PVP-coated Sp-R-300 contact lens in comparison to the frequent high-dose sparfloxacin eye drop therapy. The study demonstrated the successful application to codeliver sparfloxacin and PVP from the contact lens for the extended period to treat conjunctivitis.

Contrast sensitivity function with soft contact lens wear

PurposesTo compare contrast sensitivity function (CSF) with soft contact lens (SCL) and spectacles wear. To investigate the effect of a three-month period of SCL wear on CSF. MethodsForty-seven myopic subjects with no history of contact lens (CL) wear were included in this longitudinal prospective study. CSF was measured with spectacles using the CSV-1000 (VectorVision, Greenvile, OH). Subsequently, subjects were fitted with a daily disposable lens (Nelfilcon-A, Stenofilcon-A or Nesofilcon-A) in one eye and a monthly disposable lens (Lotrafilcon-B, Comfilcon-A or Balafilcon-A) in the other eye and wore the same type of CLs for three months. CSF was measured again on the same day and after three months wearing CLs. Differences in CSF with spectacles and CLs on baseline and changes to CSF after three months of CLs wear were assessed. The effect of lens materials and wearing modality on CSF change was also investigated. ResultsCSF was higher with CLs in comparison to the values with spectacles for spatial frequencies of 3, 6 and 12 cycles per degree (cpd) (p<0.05) while there was no difference for spatial frequency of 18 cpd (p=0.114). No significant difference was found in the CSF with CLs between baseline and after three months of lens wear (p>0.05). There was no difference in CSF between hydrogel and silicone CLs as well as when comparing daily with monthly wear CLs (p>0.05). ConclusionCSF is better with CLs than with spectacles. CSF values with CL are similar between baseline and after 3 months of lens wear.

Quantifying the pressure-dependence of work of adhesion in silicon–diamond contacts

Continuum mechanics models for contacting surfaces assume a constant interfacial energy, or work of adhesion, between materials. Recent studies have challenged this assumption, instead demonstrating that stress-dependent chemical reactions across the interface modify the work of adhesion. Here, we perform 77 adhesion tests on diamond–silicon contacts using in situ transmission electron microscopy and atomistic simulations to quantify how the adhesion changes as a function of applied pressure. The results show a sevenfold increase in the work of adhesion (from approximately 1 to 7 J/m2) with an increase in the mean applied pressure from 0 to 11 GPa, where the most significant increase occurs above 5 GPa. We rule out alternative explanations for the changing work of adhesion, such as electron-beam artifacts, bulk shape change by inelastic deformation, and time-dependent processes such as creep. Therefore, these results confirm the presence of stress-driven chemical reactions in the contact and quantify the resulting change in the adhesion of these materials with applied pressure.

Review of Rear Emitter Silicon Heterojunction Solar Cells

This inclusive study provides detailed information regarding the evolution of rear emitter silicon heterojunction solar cells. Silicon heterojunction (SHJ) solar cells of a p-type on the rear side have garnered increasing attention for various reasons. First, owing to a limitation of the p-type hydrogenated amorphous silicon layer, further optimization relative to an n-type cannot be achieved, and an accumulation of electrons at the front side allows utilizing an n-type wafer to affirm a lateral current transport. Second, better thin n-type nanocrystalline silicon (oxide) contact layers compared to p-type wafers are grown, and allow greater freedom in the structural design. The optical properties of the front side’s transparent conductive oxide (TCO) layer can be emphasized owing to a lateral transport on the cells, and majority of the carriers are affirmed through a Si substrate. In the instance of a rear emitter, the TCO layer is in relief to an adjustment inhibiting the contact resistance between TCO/a-Si:H(p). The fabrication was done in such a manner of SHJ rear emitter solar cells that they achieve greater optimization and overall efficiency of 23.46%.

Novel Polyvinyl Pyrrolidone–Loaded Olopatadine HCl–Laden Doughnut Contact Lens to Treat Allergic Conjunctivitis

Olopatadine HCl is an antiallergic drug used for the management of allergic conjunctivitis. Currently, it is delivered via eye drop solution, which is highly inefficient due to low bioavailability. Silicone contact lenses can be used to sustain the release of ophthalmic drugs. However, the presence of drug alters the optical transmittance and physical properties of the contact lens. The objective was to design a novel polyvinyl pyrrolidone (PVP)-coated olopatadine-ethyl cellulose microparticles–laden doughnut contact lens to sustained ocular delivery with limited alteration to the optical and swelling properties of the contact lens. The doughnut was implanted within the periphery of the lens using modified casting technique. Olopatadine HCl was loaded by soaking (SM-OL), direct loading (DL-OL), and doughnut casting method (DNT-OL). PVP (comfort agent) was loaded on the surface of contact lens for all the batches via novel curing technique. The in vitro olopatadine HCl release data of SM-OL (up to 48-72 h) and DL-OL batches (up to 72 h) showed high burst release, whereas DNT-OL batch showed sustained release up to 120 h without significant (p > 0.05) alteration in the optical and swelling properties of contact lens. All the batches showed sustained release of PVP up to 120 h. The in vivo studies in the rabbit tear fluid showed improvement in the olopatadine HCl and PVP retention time in comparison to eye drop solution. The PVP-loaded DNT-OL-500 lens showed tear stabilization (comfort wear) in Schirmer strip test (rabbits) with no protein adherence in comparison to DNT-OL-500 lens without PVP. The study demonstrated the successful delivery of olopatadine HCl and PVP-K30 from the doughnut contact lens for the extended period with limited alteration to the optical and swelling properties of contact lens.

High Efficiency Perovskite‐Silicon Tandem Solar Cells: Effect of Surface Coating versus Bulk Incorporation of 2D Perovskite

AbstractMixed‐dimensional perovskite solar cells combining 3D and 2D perovskites have recently attracted wide interest owing to improved device efficiency and stability. Yet, it remains unclear which method of combining 3D and 2D perovskites works best to obtain a mixed‐dimensional system with the advantages of both types. To address this, different strategies of combining 2D perovskites with a 3D perovskite are investigated, namely surface coating and bulk incorporation. It is found that through surface coating with different aliphatic alkylammonium bulky cations, a Ruddlesden–Popper “quasi‐2D” perovskite phase is formed on the surface of the 3D perovskite that passivates the surface defects and significantly improves the device performance. In contrast, incorporating those bulky cations into the bulk induces the formation of the pure 2D perovskite phase throughout the bulk of the 3D perovskite, which negatively affects the crystallinity and electronic structure of the 3D perovskite framework and reduces the device performance. Using the surface‐coating strategy with n‐butylammonium bromide to fabricate semitransparent perovskite cells and combining with silicon cells in four‐terminal tandem configuration, 27.7% tandem efficiency with interdigitated back contact silicon bottom cells (size‐unmatched) and 26.2% with passivated emitter with rear locally diffused silicon bottom cells is achieved in a 1 cm2 size‐matched tandem.