Unencapsulated Cells Research Articles

Ultrastable and efficient slight-interlayer-displacement 2D Dion-Jacobson perovskite solar cells

Stability has been a long-standing concern for solution-processed perovskite photovoltaics and their practical applications. However, stable perovskite materials for photovoltaic remain insufficient to date. Here we demonstrate a series of ultrastable Dion−Jacobson (DJ) perovskites (1,4-cyclohexanedimethanammonium)(methylammonium)n−1PbnI3n+1 (n ≥ 1) for photovoltaic applications. The scalable technology by blade-coated solar cells for the designed DJ perovskites (nominal n = 5) achieves a maximum stabilized power conversion efficiency (PCE) of 19.11% under an environmental atmosphere. Un-encapsulated cells by blade-coated technology retain 92% of their initial efficiencies for over 4000 hours under ~90% relative humidity (RH) aging conditions. More importantly, these cells also exhibit remarkable thermal (85 °C) and operational stability, which shows negligible efficiency loss after exceeding 5000-hour heat treatment or after operation at maximum power point (MPP) exceeding 6000 hours at 45 °C under a 100 mW cm−2 continuous light illumination.

Angle-Resolved Direct Emissivity Measurements on Unencapsulated Solar Cells for Passive Thermal Control

Angle-Resolved Direct Emissivity Measurements on Unencapsulated Solar Cells for Passive Thermal Control

Self-healing efficiency of later-age cracked microbial mortar embedded with unencapsulated microorganisms under long-term water and ambient exposure conditions

To ensure the long-term self-healing ability of concrete structures throughout their lifespan is a crucial requirement for Microbially Induced Carbonate Precipitation (MICP) technology. In this study, unencapsulated microbial cells were directly mixed into the fresh mortar as a component to investigate their efficiency in repairing later-age cracks, respectively exposed to long-term water environment and ambient conditions. The crack width repair ratio for samples with cracks initially created by splitting tests was calculated at healing intervals of 6 and 12 days, revealing a sixfold higher repair ratio in 150-day samples with initial widths below 200 μm than those cases with 500 μm-wide cracks. The 26.3 % reduction in water absorption content after a 12-day healing period reflected an effective healing result for cracks and capillary pores. The microbially induced calcite precipitations were confirmed through SEM, XRD, and EDS analysis, with complete crack closure observed for 150-day samples with widths less than 200 μm. However, it was also found that the self-healing efficiency decreased with increasing crack width due to the limited availability of healing agents, with the maximum completely healed crack width of 507.8 μm. Despite prolonged exposure, no further reduction in crack width and sorptivity was observed, highlighting the challenges in achieving a complete healing effect. Surface images obtained from microscopes revealed the enduring presence of unencapsulated microorganisms, corroborating their role in continuous calcite precipitation and crack filling.

Room Temperature Ionic Liquid Capping Layer for High Efficiency FAPbI3 Perovskite Solar Cells with Long-Term Stability.

Ionic liquid salts (ILs) are generally recognized as additives in perovskite precursor solutions to enhance the efficiency and stability of solar cells. However, the success of ILs incorporation as additives is highly dependent on the precursor formulation and perovskite crystallization process, posing challenges for industrial-scale implementation. In this study, a room-temperature spin-coated IL, n-butylamine acetate (BAAc), is identified as an ideal passivation agent for formamidinium lead iodide (FAPbI3) films. Compared with other passivation methods, the room-temperature BAAc capping layer (BAAc RT) demonstrates more uniform and thorough passivation of surface defects inthe FAPbI3 perovskite. Additionally, it provides better energy level alignment for hole extraction. As a result, the champion n-i-p perovskite solar cell with a BAAc capping layer exhibits a power conversion efficiency (PCE) of 24.76%, with an open-circuit voltage (Voc) of 1.19V, and a Voc loss of ≈330mV. The PCE of the perovskite mini-module with BAAc RT reaches 20.47%, showcasing the effectiveness and viability of this method for manufacturing large-area perovskite solar cells. Moreover, the BAAc passivation layer also improves the long-term stability of unencapsulated FAPbI3 perovskite solar cells, enabling a T80 lifetime of 3500h when stored at 35% relative humidity at room temperature in an air atmosphere.

Uniaxial-Oriented Perovskite Films with Controllable Orientation.

Perovskite films with large crystal size, preferred orientation, and facile fabrication process, combining advantages of single-crystal and polycrystalline films, have gained considerable attention recently. However, there is little research on the facet properties of perovskite films. Here, (111)- and (001)-oriented perovskite films with bandgaps ranging from 1.53 to 1.77eV, and systematically investigated their orientation-dependent properties are achieved. The (111)-oriented films show electron-dominated traps and the (001)-oriented films show hole-dominated traps, which are related to their atomic arrangement at the surface. Compared with the (001)-oriented films, the (111)-oriented films exhibit lower work function and superior water/oxygen robustness. For the wide-bandgap films, the lattice of the (001)-oriented film provides an unobstructed passage for ion migration. Comparably, the (111)-oriented films exhibit suppressed ion migration and excellent phase stability. The optimized unencapsulated solar cells based on both (001) and (111) orientations show a similar high efficiency of ≈23%. The (111)-oriented solar cell exhibits excellent stability, maintaining 95% of its initial efficiency after 1500h maximum power point (MPP) tracking test, and 97% initial efficiency after 3000h aging in ambient conditions. This work paves the way for the rational design, controllable synthesis, and targeted optimization of uniaxial-oriented perovskite films for various electronic applications.

Antioxidant activity, GABA (γ-aminobutyric acid) production, and potential for colonization of Lactobacillus fermentum InaCC B1295 encapsulated with cellulose microfiber hydrogel from oil palm solid waste during storage

Lactobacillus fermentum InaCC B1295 is a probiotic bacterium that improves intestinal and immune systems, positively impacting human health. It produces various bioactive compounds, including bacteriocin, antioxidant enzymes, and gamma-aminobutyric acid (GABA), and colonizes the human gastrointestinal system. This study aimed to evaluate the antioxidant activity (IC50), GABA production, and colonization potential of L. fermentum InaCC B1295 with encapsulation by cellulose microfiber from oil palm solid waste (trunk, frond, leaf, and empty bunches) at room and refrigeration temperature with storage time 0, 14, and 28 days. The strain InaCC B1295 showed a high activity to scavenging ability against DPPH (1,1-diphenyl-2-picrylhydrazyl) for the treatment with encapsulation with oil palm empty bunches at refrigeration temperature after storage 14 days, which reached 88.56 ppm. Furthermore, L. fermentum InaCC B1295 produced GABA ranging from 0.435 mg/L to 2.215 mg/L. Lactobacillus fermentum InaCC B1295 encapsulated with oil palm leaf produced the most GABA at 0-day storage with a concentration of 2.215 mg/L and decreased during storage for all treatments. L. fermentum InaCC B1295 cells encapsulated in CMF hydrogel from empty oil palm fruit bunches had a lower autoaggregation value than free cells. The cells encapsulated with CMF hydrogel from oil palm empty bunches, on the other hand, had higher coaggregation and hydrophilicity values than the free cells (unencapsulated cells).

Effect of different oxygen precursors on alumina deposited using a spatial atomic layer deposition system for thin-film encapsulation of perovskite solar cells

An atmospheric-pressure spatial atomic layer deposition system operated in atmospheric-pressure spatial chemical vapor deposition conditions is employed to deposit alumina (AlO x ) thin films using trimethylaluminum and different oxidants, including water (H2O), hydrogen peroxide (H2O2), and ozone (O3). The impact of the oxygen precursor on the structural properties of the films and their moisture-barrier performance is investigated. The O3-AlO x films, followed by H2O2-AlO x , exhibit higher refractive indexes, lower concentrations of OH− groups, and lower water-vapor-transmission rates compared to the films deposited using water (H2O-AlO x ). The AlO x films are then rapidly deposited as thin-film-encapsulation layers on perovskite solar cells at 130 °C without damaging the temperature-sensitive perovskite and organic materials. The stability of the p–i–n formamidinium methylammonium lead iodide solar cells under standard ISOS-D-3 testing conditions (65 °C and 85% relative humidity) is significantly enhanced by the encapsulation layers. Specifically, the O3-AlO x and H2O2-AlO x layers result in a six-fold increase in the time required for the cells to degrade to 80% of their original efficiency compared to un-encapsulated cells.

High‐Quality Pure‐Phase MA‐Free Formamdinium Dion‐Jacobson 2D Perovskites for Stable Unencapsulated Photovoltaics

AbstractIt is generally difficult to achieve high quality in low‐n‐value (MA‐free) FA‐based Dion‐Jacobson (DJ) 2D perovskites due to their low crystallinity, random well‐width distribution of multiple quantum wells (QWs) with disordered orientation, which has seriously hindered further advances in photovoltaics. Meanwhile, pure‐phase DJ 2D perovskites with uniform QWs width and fixed low‐n values are highly desirable for high efficiency and stability. Herein a novel 4APP(FA)3Pb4I13‐based quasi‐DJ‐2D perovskite is presented first, where 4APP is 4‐aminopiperidinium. The remarkable rigidity of 4APP and its strong hydrogen bonding with the perovskites prolong the perovskite intrinsic stability. the tri‐solvent engineering approach is further established by matching solvent properties to achieve pure‐phase DJ‐2D perovskites with uniform QWs width structure and finely oriented crystal grains, which enhance the power conversion efficiency of unencapsulated solar cells by 48%, representing one of the highest values in MA‐free DJ 2D perovskite with n≤4. Remarkably, the unencapsulated devices retain 95% of their initial PCE after 2000 h of operation under 1‐sun illumination at 40 °C, and 3000 h exposure in the air at 85 °C and 60–90% relative humidity (RH). The simultaneous control of rigidity and phase purity in DJ‐2D perovskites will open up new directions for fundamental research and application exploration.

Dual‐Interface Engineering in Perovskite Solar Cells with 2D Carbides

AbstractPassivating the interfaces between the perovskite and charge transport layers is crucial for enhancing the power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). Here we report a dual‐interface engineering approach to improving the performance of FA0.85MA0.15Pb(I0.95Br0.05)3‐based PSCs by incorporating Ti3C2Clx Nano‐MXene and o‐TB‐GDY nanographdiyne (NanoGDY) into the electron transport layer (ETL)/perovskite and perovskite/ hole transport layer (HTL) interfaces, respectively. The dual‐interface passivation simultaneously suppresses non‐radiative recombination and promotes carrier extraction by forming the Pb−Cl chemical bond and strong coordination of π‐electron conjugation with undercoordinated Pb defects. The resulting perovskite film has an ultralong carrier lifetime exceeding 10 μs and an enlarged crystal size exceeding 2.5 μm. A maximum PCE of 24.86 % is realized, with an open‐circuit voltage of 1.20 V. Unencapsulated cells retain 92 % of their initial efficiency after 1464 hours in ambient air and 80 % after 1002 hours of thermal stability test at 85 °C.

Dual-Interface Engineering in Perovskite Solar Cells with 2D Carbides.

Passivating the interfaces between the perovskite and charge transport layers is crucial for enhancing the power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). Here we report a dual-interface engineering approach to improving the performance of FA0.85 MA0.15 Pb(I0.95 Br0.05 )3 -based PSCs by incorporating Ti3 C2 Clx Nano-MXene and o-TB-GDY nanographdiyne (NanoGDY) into the electron transport layer (ETL)/perovskite and perovskite/ hole transport layer (HTL) interfaces, respectively. The dual-interface passivation simultaneously suppresses non-radiative recombination and promotes carrier extraction by forming the Pb-Cl chemical bond and strong coordination of π-electron conjugation with undercoordinated Pb defects. The resulting perovskite film has an ultralong carrier lifetime exceeding 10 μs and an enlarged crystal size exceeding 2.5 μm. A maximum PCE of 24.86 % is realized, with an open-circuit voltage of 1.20 V. Unencapsulated cells retain 92 % of their initial efficiency after 1464 hours in ambient air and 80 % after 1002 hours of thermal stability test at 85 °C.

Generation of cell-laden GelMA microspheres using microfluidic chip and its cryopreservation method

Gelatin methacrylate (GelMA) hydrogels have been widely used in tissue engineering because of their excellent biological and physical properties. Here, we used a microfluidic flow-focusing chip based on polymethyl methacrylate to fabricate cell-laden GelMA hydrogel microspheres. Structures of the throat region and photo crosslinking region on the chip, flow rate ratio of GelMA and oil phase, and GelMA concentration were optimized to obtain the stable and suitable size of microspheres. Cell-laden GelMA microspheres can be cryopreserved by slow freezing and rapid freezing. The survival rate of encapsulated cells after rapid freezing was significantly higher than that of unencapsulated cells. There was no significant difference between the results of the rapid freezing of encapsulated cells with 5% DMSO and the traditional slow freezing of suspended cells with 10% DMSO. It demonstrates the possibility that GelMA hydrogel itself can replace some of the cryoprotective agents and has some protective effect on cells. Our study provides new ideas to optimize GelMA hydrogels for cell cryopreservation, facilitating the off-the-shelf availability of tissue-engineered constructs.

Overcoming Moisture‐Induced Degradation in Organic Solar Cells

Unencapsulated organic solar cells are prone to severe performance losses in the presence of moisture. Accelerated damp heat (85 °C/85% RH) studies are presented and it is shown that the hygroscopic hole‐transporting PEDOT:PSS layer is the origin of device failure in the case of prototypical inverted solar cells. Complementary measurements unveil that under these conditions a decreased PEDOT:PSS work function along with areas of reduced electrical contact between active layer and hole‐transport layer are the main factors for device degradation rather than a chemical reaction of water with the active layer. Replacements for PEDOT:PSS are explored and it is found that tungsten oxide (WO3) or phosphomolybdic acid (PMA)—materials that can be processed from benign solvents at room temperature—yields comparable performance as PEDOT:PSS and enhances the resilience of solar cells under damp heat. The stability trend follows the order PEDOT:PSS << WO3 < PMA, with PEDOT:PSS‐based devices failing after few minutes, while PMA‐based devices remain nearly pristine over several hours. PMA is thus proposed as a robust, solution‐processable hole extraction layer that can act as a one to one replacement of PEDOT:PSS to achieve organic solar cells with significantly improved longevity.

Dual Functions of Defect Passivation and Hole Transport Dopant Enabled by Piperidyl Ionic Liquid for Stable and Efficient Perovskite Solar Cells

Perovskite solar cells (PSCs) have recently attracted rapid interest for harvesting solar energy. However, the defects in perovskite absorber and vulnerability of charge‐transporting layer lead to unsatisfying stability, which limits their practical applications. Herein, we demonstrate that the addition of a piperidyl ionic liquid, that is, 1‐butyl‐1‐methylpiperidinium bis(trifluoromethyl sulfonyl)imide ([BMP]+[TFSI]−), can serve as a dual functional additive for passivating the intrinsic defects in perovskite and simultaneously improving the hydrophobicity of hole transport layer. Consequently, the power conversion efficiency for the optimal planar PSCs significantly increases from 21.07% to 23.34%. Impressively, the unencapsulated champion cells display promising stability with a reservation over 80% of the initial efficiency after exposure to moisture air (65% ± 5% relative humidity) for 1600 h. This work provides a facile strategy toward enhancing the efficiency and stability of PSCs.

Surface Passivation of Organic-Inorganic Hybrid Perovskites with Methylhydrazine Iodide for Enhanced Photovoltaic Device Performance

Organic-inorganic hybrid perovskites are highly efficient in photovoltaic applications, making the commercialization of perovskite solar cells (PSCs) possible. However, the high density of defects on the surface significantly affects the performance of PSCs. To address this issue, we have demonstrated a facile post-treatment strategy utilizing methylhydrazine iodide (MHyI) to passivate the surface of the perovskite film. MHyI could co-ordinate with the dangling bonds on the surface of perovskite films, effectively passivating defects in the film and suppressing carrier non-radiative recombination. As a result, PSCs with MHyI modification exhibit a champion power conversion efficiency (PCE) of 23.19% and a high open-circuit voltage (VOC) of 1.14 V (0.43 V voltage deficit). Moreover, unencapsulated solar cells maintain their initial efficiency of 88% after 30 days of exposure to ambient air with 30% humidity, and the devices with encapsulation retained 57% of their initial efficiency after 200 h of maximum power point (MPP) loading under constant light irradiation in ambient air. Overall, our results provide a facile method for improving the performance and stability of PSCs.

Green tea polysaccharide conjugates and gelatin enhanced viability of L. acidophilus by layer-by-layer encapsulation

Adverse environments such as the gastrointestinal tract can affect the efficacy of probiotics. Therefore, the adequate protection of probiotics and their total effect exertion are probiotics application research hotspots. Green tea polysaccharide conjugate (gTPC), an anionic polymer, and gelatin as the encapsulation materials, and layer-by-layer self-assembly technology as the method, were applied to encapsulate Lactobacillus acidophilus. Microscopic results showed that with the increase in the number of deposited layers, the encapsulation was more complete. After continuous exposure to simulated gastrointestinal fluid for 120 min, the survival rate of unencapsulated cells was 53.26%, and encapsulated cells with different deposited layers were 66.00%, 71.99%, 76.94%, and 79.89%, respectively. In addition, Gel/gTPC bilayers can efficiently improve cell thermotolerance and freezing resistance. Results indicated that the more the number of Gel/gTPC bilayers, the more significant the protection is. Therefore, gTPC and Gel are viable materials to protect probiotics through microencapsulation by Layer-by-layer self-assembly.

Impact of concentration of DMF and H2O on photovoltaic properties of SnO2-based planar perovskite solar cells

SnO2-based planar perovskite solar cells were prepared via the sol-gel method and DMF was used to coordinate with SnCl4 which ensures to form a stable Sn-sol. A certain amount of H2O was added to induce SnCl4 to convert to SnO2 and reduce the remaining of OH− and Cl− on the surface of SnO2 film. Compared with the PCE of pristine SnO2-based cells (17.14%), the W-SnO2-based cell in revers scan under simulated AM1.5G illumination increases to 19.07%. The open-circuit voltage of the W-SnO2-based cells increases to 1128 mV, compared with that of the pristine SnO2-based cell (1090 mV). The unencapsulated cells maintain 90% of initial efficiency after stored in Ar glovebox for 30 days.

Synergistic Surface Modification of Tin-Lead Perovskite Solar Cells.

Interfaces in thin-film photovoltaics play a pivotal role in determining device efficiency and longevity. Herein, we study the top surface treatment of mixed tin-lead (∼1.26eV) halide perovskite films for p-i-n solar cells. We are able to promote charge extraction by treating the perovskite surface with piperazine. This compound reacts with the organic cations at the perovskite surface, modifying the surface structure and tuning the interfacial energy level alignment. In addition, the combined treatment with C60 pyrrolidine tris-acid (CPTA) reduces hysteresis and leads to efficiencies up to 22.7%, with open-circuit voltage values reaching 0.90V, ∼92% of the radiative limit for the band gap of this material. The modified cells also show superior stability, with unencapsulated cells retaining 96% of their initial efficiency after >2000 hours of storage in N2 and encapsulated cells retaining 90% efficiency after >450 hours of storage in air. Intriguingly, CPTA preferentially binds to Sn2+ sites at film surface over Pb2+ due to the energetically favoured exposure of the former, according to first-principles calculations. This work provides new insights into the surface chemistry of perovskite films in terms of their structural, electronic, and defect characteristics and we use this knowledge to fabricate state-of-the-art solar cells. This article is protected by copyright. All rights reserved.

Scalable Non-Halogenated Co-solvent System for Large-Area, Four-Layer Slot-Die-Coated Organic Photovoltaics

Sustainable processing solvents, photoactive materials, and scalable manufacturing will play a key role in commercializing printed organic photovoltaics (OPVs). The record-breaking pioneering OPV reports have done an outstanding job in accelerating the discovery of champion photoactive materials and device engineering practices; however, these works predominantly involve health-hazardous halogenated processing solvents/additives and non-scalable thin-film coating methods. Herein, large-area slot-die-manufactured OPV cells from eco-friendly halogen-free solvents and synthetically scalable materials are showcased. All the four layers; electron transport layer (SnO2), cathode interlayer (PDIN-H), bulk-heterojunction (BHJ, PTQ-10:BTP-4F-12), and hole transport layer [poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) (PEDOT:PSS] are slot-die-coated in air. A non-halogenated co-solvent mixture of toluene and 2-methyl tetrahydrofuran is presented as an optimal processing solvent to realize the high-quality thin films of PTQ10:BTP-4F-12. The unencapsulated champion solar cells characterized in ambient conditions (RH = 30%, T = 22 °C) exhibit power conversion efficiencies (PCEs) of 12.1 and 17.8% under 1 Sun (100 mW/cm2) and indoor light-emitting diode lighting (580 μW/cm2) conditions, respectively. Additionally, PEDOT:PSS is successfully slot-die-coated atop BHJ by mitigating wettability challenges with the aid of surface treatment. The all four-layer slot-die-coated OPVs exhibit a PCE of 9.55%.

Pre-annealing treatment for high-efficiency perovskite solar cells via sequential deposition

<h2>Summary</h2> Grain boundaries (GBs) have been shown to initiate metal halide perovskite degradation under light, moisture, and/or heat stresses due to the existence of various defects, making them extremely vulnerable in perovskite solar cells (PSCs). Although various post-treatments have been proven to be effective in repairing GBs, preventing the degradation from perovskite GBs remains an extremely difficult challenge. We report here a generic pre-annealing treatment for reconstructing sequentially deposited perovskite crystallites and GBs. With this strategy, robust GBs are created upon defect suppression with preferred oriented large perovskite grains. As a result, the resultant n-i-p-structured PSCs deliver an impressive power conversion efficiency of nearly 25% and an extremely high fill factor of 85.5%. The unencapsulated cells maintain 81% of their initial efficiencies after 1,000 h of continuous operation at maximum power point at about 55°C in an inert atmosphere, showing greatly improved light stability.

π-Conjugated Carbazole Cations Enable Wet-Stable Quasi-2D Perovskite Photovoltaics

Quasi-two-dimensional halide perovskites are commonly used in solar cells, as they are more stable than their three-dimensional analogues. Nevertheless, it is still challenging to meet the stability requirements under high-humidity conditions. Here, we design π-conjugated carbazole (CA) cations to increase the water resistance of perovskite. We control the crystallization kinetics by the anti-solvent strategy to locate the hydrophobic low-⟨n⟩-value phase on the surface of the perovskite film. The resulting CA2MA4Pb5I16 film does not decompose after being immersed in water for several minutes. We further regulate the vertical orientation of perovskite crystals by introducing NH4SCN additive, resulting in improved carrier transport dynamics. As a result, the optimized CA2MA4Pb5I16 device achieves a notable power conversion efficiency (PCE) of 18.23% and retains more than 85% of the original PCE after 2000 h under a relative humidity of 65% at 25 °C. This is one of the most stable reported unencapsulated perovskite solar cells in high-humidity environments.