Interface Passivation Research Articles

Optimization of rear surface morphology in n-type TOPCon c-Si solar cells

Tunnel oxide passivated contact (TOPCon) crystalline silicon (c-Si) solar cells have attracted much attention because of their superior electrical properties such as the lower contact resistivity and better interface passivation at high temperatures. However, the TOPCon c-Si solar cells also have room for further improvement in optical performance, and the embodiment of optical advantages needs to be matched synchronously in electrical aspect. Here, the rear silicon pyramids with different angles have been achieved through solution corrosion to maximize the light absorption in the c-Si substrate. The light absorption for the pyramid angle of less than 30° is better. Compared with the cell samples with rear pyramid for a certain angle, the samples with flat back surface possess better surface passivation, and the contact resistivity can be reduced effectively by increasing the phosphorus doping concentration and adjusting the annealing temperature. Furthermore, the TOPCon c-Si solar cells with flat rear surface covered by 70 nm poly-Si have been demonstrated to increase the conversion efficiency by about 0.15 % vs. the counterpart for poly-Si of 130 nm thickness, and the improvement is mainly due to the increase of JSC and FF by 0.07 mA/cm2 and 0.72 %, respectively.

Multifunctional molecular bridge enabled interface passivation and strain release for stable and efficient all-inorganic perovskite solar cells

The precise management of the buried interface in n-i-p perovskite solar cells (PSCs) to achieve efficient charge extraction and transport is crucial for improving the photovoltaic performance. Here, a 4-chloro-2,5-dimethoxyaniline (CDA) modifier with multifunctional groups is utilized as a molecular bridge at the TiO2/CsPbBr3 buried interface to enhance the qualities of TiO2 and CsPbBr3 films and the arrangement of interface energy level. The chlorine atom in CDA can heal the oxygen vacancies defects on the TiO2 film surface, thereby improving its electron mobility and conductivity. The –O– and -NH2 groups in CDA play a passivation effect on the ions defects of CsPbBr3 film, and especially the two –O– groups can anchor the lattice Pb atoms of CsPbBr3 perovskite, which effectively reduce the trap states of CsPbBr3 film and release the residual lattice strain. The modification of CDA also improves the wettability and energy level of TiO2 film to optimize CsPbBr3 crystal growth and charge transport, respectively. Consequently, the CsPbBr3 PSCs with CDA molecular bridge free of encapsulation achieve a highly increased power conversion efficiency of 10.85%, in contrast with 8.16% value of the control device. After 720 h of storage at 85 °C and in air environment with 85% relative humidity, the efficiency of the CDA-modified device retains 93.1% of the initial value, demonstrating excellent long-term humidity and thermal stability.

Enhancement of Cd‐Free All‐Dry‐Processed Cu(In1‐x,Gax)Se2 Thin‐Film Solar Cells by Simultaneous Adoption of an Enlarged Bandgap Absorber and Tunable Bandgap Zn1‐xMgxO Buffer

Attempts to remove environmentally harmful materials in mass production industries are always a major issue and draw attention if the substitution guarantees a chance to lower fabrication cost and to improve device performance, as in a wide bandgap Zn1‐xMgxO (ZMO) to replace the CdS buffer in Cu(In1‐x,Gax)Se2 (CIGSe) thin‐film solar cell structure. ZMO is one of the candidates for the buffer material in CIGSe thin‐film solar cells with a wide and controllable bandgap depending on the Mg content, which can be helpful in attaining a suitable conduction band offset. Hence, compared to the fixed and limited bandgap of a CdS buffer, a ZMO buffer may provide advantages in Voc and Jsc based on its controllable and wide bandgap, even with a relatively wider bandgap CIGSe thin‐film solar cell. In addition, to solve problems with the defect sites at the ZMO/CIGSe junction interface, a few‐nanometer ZnS layer is employed for heterojunction interface passivation, forming a ZMO/ZnS buffer structure by atomic layer deposition (ALD). Finally, a Cd‐free all‐dry‐processed CIGSe solar cell with a wider bandgap (1.25 eV) and ALD‐grown buffer structure exhibited the best power conversion efficiency of 19.1%, which exhibited a higher performance than the CdS counterpart.

Chemistry and Formation of Solid-Electrolyte Interphase (SEI) at Li-Metal Potential

Li metal batteries (LMBs) have long been considered a solution to address the energy density limitations of Li-ion batteries. However, the widespread adoption of LMBs has faced challenges due to operational issues, notably safety concerns arising from the formation of Li dendrites and uncontrolled reactivity at the interfaces, leading to continuous consumption of the electrolyte. To enhance the reversibility of the Li-metal anode (LMA), a promising approach has emerged involving the development of a novel liquid electrolyte comprising an ether solvent and LiFSI salt. Notably, this electrolyte formulation has achieved impressive Coulombic efficiency (CE) values surpassing 99.5%. Despite this progress, the underlying causes of Coulombic inefficiency (CI) and its connection with the formation of a solid-electrolyte interphase (SEI) on the Li metal surface remain inadequately understood.Gaining fundamental insights into these essential processes occurring during continuous cycling of the LMA can provide valuable guidance for optimizing CE more effectively. This presentation focuses on recent advancements that systematically unravel the underlying chemistry and formation of SEI derived from FSI anions at the interface of the Li metal anode in contact with various liquid electrolytes. By employing a non-washing protocol and a Cu current collector, we successfully captured and identified crucial reaction intermediates from SEI chemistry, enabling precise determination of the decomposition pathway for FSI anions. Our discoveries unveil a dynamic scenario at the electrode/electrolyte interface, where these reaction byproducts can significantly dissolve into the liquid layer, and their relative solubility dictates their role in passivating the electrode surface. Furthermore, we demonstrate a strong correlation between faster interfacial passivation in higher-performing electrolytes and the reduced solubility of diverse inorganic species within the liquid electrolyte. These fresh insights into SEI chemistry and formation open new avenues for enhancing LMA performance by mitigating undesired side reactions at the interface.

High‐Performance Perovskite Solar Cell via Chirality‐Engineered Graphene Quantum Dot Interface Passivation

High‐Performance Perovskite Solar Cell via Chirality‐Engineered Graphene Quantum Dot Interface Passivation

Photocontrolled interfacial defect passivation of coumarin 151 with enhanced hydrophobicity for stable perovskite solar cell

Defect passivation has been recognized as an efficient strategy to boost the performance of perovskite solar cells (PSCs) for commercial applications. However, most reported strategies overly emphasize passivation of undesirable defects, while ignoring the inherent instability of perovskite materials caused by environmental risks. In this study, we explore a groundbreaking strategy to integrate various functions of defect passivation, photoresponsivity and photocontrolled hydrophobicity in one device via the surface engineering of 7-amino-4-trifluoromethylcoumarin (C151). The detailed experiments demonstrate that C151 based PSCs have regulated power conversion efficiency and stability responding to UV illumination due to the photodimerization of coumarin. On the one hand, the photodimer of C151 (C151-L) can form stronger chelation with various defect sites in comparison with C151, resulting in optimized energy level arrangement, superior charge extraction/transport and significantly inhibited nonradivation recombination. One the other hand, morphological changes of the perovskite film triggered by UV illumination also bring convertible surface hydrophobicity transition. As a result, the unpackaged C151-L modified device exhibits excellent stability maintaining 91% of its initial PCE after aging for 1000 h under a relative humidity of 30%–40% at 20 °C. Moreover, C151-L plays a positive role in improving the operation stability against high humidity, continuous UV radiation, and heating stress. This work may offer more choices for materials with tunable properties in high-efficiency optoelectronic devices.

Interfacial Passivation of Kesterite Solar Cells for Enhanced Carrier Lifetime: Ab Initio Nonadiabatic Molecular Dynamics Study

AbstractNonradiative recombination at the front contact interface of kesterite solar cells hinders the extraction of photo‐generated carriers, significantly restricting the efficiency enhancement. However, identifying the recombination centers and proposing effective passivation strategies remain open questions. First‐principles calculations combining with nonadiabatic molecular dynamics (NAMD) simulations unveil that the interfacial translational symmetry breaking in elemental valence states leads to a detrimental donor‐like Cu2ZnSnS4/CdS interface with deep states originating from the interfacial Sn‐5s orbital, which serve as significant nonradiative recombination centers. Here, two mechanisms are proposed for eliminating the deep interface states: 1) directly replacing Sn‐5s with higher outer orbital levels by substituting group IIIA elements (In and Ga) for the interfacial Sn atom; 2) introducing an extra defect‐level coupling with Sn‐5s by substituting group VA elements (N, P, and As) for the S atoms bonded with the interfacial Sn atom. The representative InSn and PS acceptor defects, which are energetically favorable at the detrimental donor‐like interface, effectively passivate the deep interface states, markedly improving the carrier lifetimes by weakening nonadiabatic coupling between the band edge and the interfacial states. This study reveals the origin of the interfacial nonradiative recombination of kesterite solar cells and offers insights into interfacial passivation in semiconductor devices.

NiOx Passivation in Perovskite Solar Cells: From Surface Reactivity to Device Performance.

Nonstoichiometric nickel oxide (NiOx) is one of the very few metal oxides successfully used as hole extraction layer in p-i-n type perovskite solar cells (PSCs). Its favorable optoelectronic properties and facile large-scale preparation methods are potentially relevant for future commercialization of PSCs, though currently low operational stability of PSCs is reported when a NiOx hole extraction layer is used in direct contact with the perovskite absorber. Poorly understood degradation reactions at this interface are seen as cause for the inferior stability, and a variety of interface passivation approaches have been shown to be effective in improving the overall solar cell performance. To gain a better understanding of the processes happening at this interface, we systematically passivated specific defects on NiOx with three different categories of organic/inorganic compounds. The effects on NiOx and the perovskite (MAPbI3) deposited on top were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Here, we find that the perovskite's structural stability and film formation can be significantly affected by the passivation treatment of the NiOx surface. In combination with density functional theory (DFT) calculations, a likely origin of NiOx-perovskite degradation interactions is proposed. The surface passivated NiOx layers were incorporated into MAPbI3-based PSCs, and the influence on device performance and operational stability was investigated by current-voltage (J-V) characterization, impedance spectroscopy (IS), and open circuit voltage decay (OCVD) measurements. Interestingly, we find that a superior structural stability due to interface passivation must not relate to high operational stability. The discrepancy comes from the formation of excess ions at the interface, which negatively impacts all solar cell parameters.

Interfacial engineering and defect passivation of SnO2 through agmatine sulfate in carbon-based perovskite solar cells

Electron transport layer has always played a crucial role in the performance of the perovskite solar cells (PSCs). Particularly, SnO2-based PSC has sparked considerable interest due to its superior properties. Even with such remarkable properties, certain challenges persist such as agglomeration of SnO2 particles which can lead to interfacial defects and poor morphology. To solve this problem, Agmatine Sulfate (AGTS) has been introduced as an interfacial modification agent which with the help of its active functional group including amide (-NH2) and hydroxyl (OH) has allowed to facilitate the interaction at the interface between SnO2 and perovskite. The interaction facilitates the growth of perovskite crystals while tuning the energy levels which has boosted the charge transfer capability of the layer. All these improvements in the properties have led to enhanced power conversion efficiency (PCE) from 11.17 % to 15.20 % for the encapsulated device. Furthermore, the modification also improved the long-term stability of the device as the AGTS-modified devices retained 87 % of their performance at 15–25 °C with humidity levels between 10 and 20 % for over a period of 31 days. Finally, the devices prepared with the AGTS also showed repeatability in their performance while boosting the overall performance of carbon-based PSCs (C–PSCs) and indicating a novel approach to not only increase but also accelerate the commercialization of C-PSC.

Spiro-OMeTAD Anchoring perovskite for gradual homojunction in stable perovskite solar cells

The role of interface energetics-modification in interface-defect passivation and optimal interface energy-level matching is assumed to be a crucial aspect. Enhancing the performance and durability of perovskite solar cells (PSCs) can be achieved through this strategy. Here, spiro-OMeTAD [2,2′,7,7′-tetrakis (N, N-di-p-methoxyphenylamine)-9,9′-spirobifluorene] has been pipetted onto the spinning perovskite precursor film via a chlorobenzene anti-solvent strategy. It is found that spiro-OMeTAD serves as not only the filler at grain boundaries, but also the coverage on perovskite’s grain, and then forms the gradual homojunction interface from perovskite to spiro-OMeTAD hole transport layer, which can make spiro-OMeTAD anchor perovskite via the reaction between Pb2+ and C-O groups to decrease the interface barrier and obtain the optimal interface energy-level match between them for hole −migration and −collection. Moreover, these fillers or coverages can prevent moisture invading perovskite. Consequently, the counterpart PSC achieves a champion efficiency of 24.46 %, and has retained more than 88 % of the initial efficiency after 224 days of storage.

Columnar self-assembled heteroatom bay-annulated perylene bisimide as passivating layer for high performance perovskite solar cells

The interfaces within Perovskite solar cells (PSCs) are imperative for regulating defects, managing carrier dynamics, preventing ion migration, optimizing energy band alignment, and controlling morphology. The interfaces amidst the absorber layer and the hole transport layer (HTL) pose challenges related to ineffective charge extraction and charge recombination, necessitating enhancement. Spiro-OMeTAD is commonly utilized as p-type material in the HTL of planar architecture, entailing the inclusion of diverse additives to enhance solar cell efficiency, which can restrict device performance and stability. Herein, we explore the influence of a discotic liquid crystalline (DLCs) based semiconductor, a heteroatom bay-annulated perylene bisimide (PBI-SeO10), which is derived from tri-n-alkoxy anilines. Our study examines the function of PBI-SeO10 as an interfacial passivation layer within the perovskite/Spiro-OMeTAD interface, assessing its effects on both device performance and stability. Our results indicate that integrating PBI-SeO10 as a surface passivation layer not only aids in effective hole extraction from the perovskite layer but also substantially diminishes defects, leading to an improvement in overall device performance by approximately 7 %. Furthermore, PBI-SeO10 passivation also reduces ionic/molecular species diffusion into the device and provides good moisture resistivity leading to improved device stability.

23.81%-Efficiency Flexible Inverted Perovskite Solar Cells with Enhanced Stability and Flexibility via a Lewis Base Passivation.

Lewis base molecules bind the undercoordinated lead atoms at interfaces and grain boundaries, leading to the high efficiency and stability of flexible perovskite solar cells (PSCs). We demonstrated a highly efficient, stable, and flexible PSC via interface passivation using a Lewis base of tri(o-tolyl)phosphine (TTP). It not only induced an intimate interface contact and a complete deposition of the perovskite thin layers on hole transport layers (HTLs) but also led to a better perovskite with a raised crystallinity, fewer defects, and a better morphology, including fewer gullies, high uniformity, and low roughness. Furthermore, the TTP treatments induced a good alignment of energy levels among the perovskites, HTLs, and C60. The resultant flexible inverted PSCs exhibited a high power conversion efficiency (PCE) of 23.81%, which is one of the highest PCEs among these flexible inverted PSCs. Moreover, the optimized flexible PSCs exhibited high storage stability, superior operation stability, and enhanced mechanical flexibility. This study presents an effective method to substantially raise the PCE, stability, and mechanical flexibility of the flexible inverted perovskite photovoltaics.

Fabrication of a Porous Copper/Graphite/Zirconium Oxide Hybrid Anode via Screen Printing for Lithium‐Ion Batteries

AbstractRedesigning anode structures in Li‐ion batteries (LIBs) has been a focus of research aimed at surpassing the energy density of conventional LIBs. Although anode‐free LIBs present a promising architecture, their low Coulombic efficiency is a major drawback. This paper introduces a novel hybrid anode that integrates the current collector (CC) and active materials into a single, cohesive porous structure, which supports both de/intercalation and de/plating reactions. The hybrid anode consists of a porous Cu matrix with embedded ZrO2 powders and graphite; the quantity of graphite is only a third of that present in a traditional graphite anode. The porous structure and additives enhance the electrochemical performance of the hybrid anode by minimizing the Li–electrolyte interactions, forming a stable solid–electrolyte interface and Li4Zr3O8 passivation layer, and reducing the nucleation overpotential. Especially, the unique surface morphology, characterized by a negative curvature between sintered Cu particles, lowers the diffusion potential, which further reduces the nucleation overpotential. Additionally, the periodic mesh‐imprinted top surface, created via screen printing, promotes uniform Li plating. The results demonstrate that the cycling performance and energy density offered by the fabricated hybrid anode are superior to those of conventional graphite anodes.

Tailoring perovskite crystallization and interfacial passivation in efficient, fully textured perovskite silicon tandem solar cells

Tailoring perovskite crystallization and interfacial passivation in efficient, fully textured perovskite silicon tandem solar cells

Additive and interface passivation dual synergetic strategy enables reduced voltage loss in wide-bandgap perovskite solar cells

The open-circuit voltage (VOC) loss for wide-bandgap (WBG) perovskite solar cells (PSCs) is a significant obstacle to their further development. Herein, we introduce a dual approach involving mixed potassium thiocyanate and potassium chloride (KSCN+KCl) additives combined with 2-thiophene methylamine iodine (2-ThMAI) post-passivation strategy to mitigate VOC loss in WBG PSCs. In the mixed additives, KSCN can expand the grains and reduce the grain boundary, while KCl can inhibit the migration of halogen ions, effectively preventing phase segregation in WBG perovskites under the combination of both. However, due to the substantial energy level mismatch at the perovskite/electron transport layer (ETL) interface, suppressing phase segregation alone is insufficient to reduce the VOC loss. Therefore, introducing 2-ThMAI interface passivation could uniform spatial distribution of perovskite surface potential, promote energetic alignment at perovskite/electron transport layer interface, and further reduce the VOC loss. With these optimizations, the champion WBG PSCs achieved an enhanced VOC of 1.327 V and a promising power conversion efficiency (PCE) of 19.44 %. Additionally, these modified WBG PSCs retained 94 % of their initial efficiency after 500 hours of continuous light soaking at maximum power point tracking in ambient conditions.

Effects of Al2O3 Rear Interface Passivation on the Performance of Bifacial Kesterite‐Based Solar Cells with Fluorine‐Doped Tin Dioxide Back Contact

Herein, ultrathin Al2O3 is investigated as a rear interface passivation layer for kesterite solar cells with F:SnO2 (FTO) back contact for potential performance improvement. On the passivation layer, a thin Mo layer is deposited to improve the FTO's ohmicity. Further, NaF is evaporated on the copper zinc tin sulfide (CZTS) precursors to create openings at the passivation layer and achieve Na‐induced benefits in the absorber. The CZTS absorbers deposited directly on the Al2O3‐coated FTO peel off, while those with Mo interlayer do not. For pure sulfide kesterite devices, the Al2O3 layer reduces the short‐circuit current density (JSC), resulting in poor device efficiency. On the other hand, significantly higher JSC is realized for mixed sulfide and selenide kesterite devices with Al2O3 passivation layer, with the current density–voltage curve suggesting a reduced barrier height at the rear interface. As a result, the efficiency is improved from 1.5% for devices without Al2O3 to 4.6% for those with Al2O3. Likewise, improved external quantum efficiency response is observed in the devices with passivation layer for backside and frontside illumination. Therefore, contribution of Al2O3 passivation layer to the performance of kesterite‐based solar cells is evident from the results of this study.

Silicon‐Inspired Analysis of Interfacial Recombination in Perovskite Photovoltaics

AbstractPerovskite solar cells have reached an impressive certified efficiency of 26.1%, with a considerable fraction of the remaining losses attributed to carrier recombination at perovskite interfaces. This work demonstrates how time‐resolved photoluminescence spectroscopy (TRPL) can be utilized to locate and quantify remaining recombination losses in perovskite solar cells, analogous to methods established to improve silicon solar cell passivation and contact layers. It is shown how TRPL analysis can be extended to determine the bulk and surface lifetimes, surface recombination velocity, the recombination parameter, J0, and the implied open‐circuit voltage (iVoc) of any perovskite device configuration. This framework is used to compare 18 carrier‐selective and passivating contacts commonly used or emerging for perovskite photovoltaics. Furthermore, the iVoc values calculated from the TRPL‐based framework are directly compared to those calculated from photoluminescence quantum yields and the measured solar cell Voc. This simple technique serves as a practical guide for screening and selecting multifunctional, passivating perovskite contact layers. As with silicon solar cells, most of the material and interface analysis can be done without fabricating full devices or measuring efficiency. These purely optical measurements are even preferable when studying bulk and interfacial passivation approaches, since they remove complicating effects from poor carrier extraction.

Enhancing efficiency in inverted perovskite solar cells: The role of dual-site binding ligands

Despite the rapid progress in efficiency, PSCs encounter substantial challenges regarding durability and scalability. Inverted p-i-n PSCs provide enhanced long-term operating stability over the conventional n-i-p structures but lag in PCE (Park and Zhu, 2020 [3]). This limitation is mainly due to the interface between the perovskite light-absorbing layer and charge transport materials, where energy band misalignment and energy level pinning hinder PCE. Furthermore, surface defects exacerbate these constraints. In the endeavor to improve performance of PSCs, surface passivation is crucial for reducing nonradiative recombination at the interface. A recent study by Chen et al., published in the journal Science, introduces an innovative interface passivation strategy for p-i-n PSCs that could set a new benchmark for efficiency and stability (Chen et al., 2024 [4]). This commentary assesses the potential impact of dual-site-binding ligands on PSCs and anticipates their transformative effect on the field.

Atomic-scale understanding on the influence of sliding angle on the interfacial structure and friction behavior of textured amorphous carbon films

Textured amorphous carbon (T:a-C) films have received great attention in the fields of hard drives, MEMS, and NEMS due to their excellent tribological properties. However, there is still a lack of research on the dependence of its friction behavior on different sliding angles. Especially, owing to the limitations of in-situ characterization in capturing the friction interface information, the potential friction mechanisms are still unclear. Hence, in this work T:a-C film with a rectangular shape was constructed and the impact of different sliding angles on friction behavior under dry friction condition was mainly explored through reactive molecular dynamics simulation. Results unveil that the friction properties of T:a-C films are closely dependent on the sliding angle. When the sliding angle increases from 0° to 45°, the decrease in the number of CC covalent bonds at the friction interface weakens the interfacial crosslinking effect, leading to a decrease in the friction coefficient by 20.11 %. However, as the sliding angle further increases from 45° to 90°, an increase in friction coefficient is observed, which is due to the increase of unsaturated bond content, weakening the interface passivation effect. These results reveal the friction mechanism of T:a-C films, induced by sliding angle, and effectively guide the design and technical application of textured a-C films.

Preparation and characterization of medium entropy alloy CrCoNi toughened SiC ceramics

SiC is a promising structural material for future advanced nuclear energy systems. However, the inherent brittleness and difficulty of densification of SiC limits its practical application. In this study, medium entropy alloy (CrCoNi) reinforced silicon carbide composites (CCN/SiC) were sintered at 1950–2200°C by spark plasma sintering (SPS). The influence of CCN addition on the CCN/SiC composites was investigated in terms of microstructure, mechanical and thermal properties. The results show that SiC sintered at 2200℃ has the highest density, and the addition of 7.5 wt% CCN can significantly improve the fracture toughness of SiC. Transgranular fracture, crack deflection, and premature crack termination due to interfacial passivation are considered as potential toughening mechanisms. Although the addition of CCN can degrade the thermal conductivity of SiC ceramics, it has little effect on the structural stability of the SiC matrix at high temperatures.