Passivating Agent Research Articles

Citric Acid in the Passivation of Titanium Dental Implants: Corrosion Resistance and Bactericide Behavior.

The passivation of titanium dental implants is performed in order to clean the surface and obtain a thin layer of protective oxide (TiO2) on the surface of the material in order to improve its behavior against corrosion and prevent the release of ions into the physiological environment. The most common chemical agent for the passivation process is hydrochloric acid (HCl), and in this work we intend to determine the capacity of citric acid as a passivating and bactericidal agent. Discs of commercially pure titanium (c.p.Ti) grade 4 were used with different treatments: control (Ctr), passivated by HCl, passivated by citric acid at 20% at different immersion times (20, 30, and 40 min) and a higher concentration of citric acid (40%) for 20 min. Physical-chemical characterization of all of the treated surfaces has been carried out by scanning electronic microscopy (SEM), confocal microscopy, and the ‘Sessile Drop’ technique in order to obtain information about different parameters (topography, elemental composition, roughness, wettability, and surface energy) that are relevant to understand the biological response of the material. In order to evaluate the corrosion behavior of the different treatments under physiological conditions, open circuit potential and potentiodynamic tests have been carried out. Additionally, ion release tests were realized by means of ICP-MS. The antibacterial behavior has been evaluated by performing bacterial adhesion tests, in which two strains have been used: Pseudomonas aeruginosa (Gram–) and Streptococcus sanguinis (Gram+). After the adhesion test, a bacterial viability study has been carried out (‘Life and Death’) and the number of colony-forming units has been calculated with SEM images. The results obtained show that the passivation with citric acid improves the hydrophilic character, corrosion resistance, and presents a bactericide character in comparison with the HCl treatment. The increasing of citric acid concentration improves the bactericide effect but decreases the corrosion resistance parameters. Ion release levels at high citric acid concentrations increase very significantly. The effect of the immersion times studied do not present an effect on the properties.

Interfacial engineering from material to solvent: A mechanistic understanding on stabilizing [formula omitted]-formamidinium lead triiodide perovskite photovoltaics

Formamidinium lead triiodide (FAPbI3) has recently been considered as the most promising candidate to achieve highly efficient perovskite solar cells (PSCs). Excitingly, the state-of-the-art highest efficiency of FAPbI3 based PSCs have reached over 25%. However, their device stability still lags behind other compositions of mixed-cation and mixed-halide perovskites. Interfacial engineering is a very powerful method to address this issue and passivation agents have been intensively developed, however there is a lack of in-depth understanding regarding the solvent selection during post-treatment. Here, we employed cyclohexylmethylammonium iodide (CMAI) as passivation agent, which is investigated using either isopropanol (IPA) or chloroform (CF) as carrier mediator to study the solvent influence on the stabilization of FAPbI3. We observed a suppressed-defect perovskite surface toward distinguished composition with 2D CMA2PbI4 domain and CMAI domain induced by IPA and CF, respectively. Remarkably, post-treatment with solution of CMAI in CF creates a strain-free environment on the perovskite surface, leading to an improved efficiency of approaching 24% and concurrently an extraordinarily stable α-phase FAPbI3 PSCs under operation condition, retaining 95% of its initial efficiency after 1050-hour aging. Our resulting device stability is one of the most stable FAPbI3 based PSCs reported in literature.

Silk fibroin induced homeotropic alignment of perovskite crystals toward high efficiency and stability

The photoactive lead halide perovskites with a highly crystalline structure and low trap state density were regarded as the prerequisites for achieving high photovoltaic performance. The perovskite thin films were typically synthesized by simple wet chemistry routes, where the fluctuations in the fabrication readily generate lattice defects and induce stacking faults during the crystal growth. The growth of highly crystalline and low-defect perovskite usually needs complicated synthetical manipulation and well-designed additive engineering. Here in this work, we reported a naturally available protein, silk fibroin (SF), whereby the highly ordered β-sheets component can adequately interact with perovskite intermediates and work as the crystal growth template and trap passivation agent, which induced facile self-assembly of the perovskite crystals with homeotropic alignment structure and low defect concentrations. As a result, the SF incorporated perovskite layer exhibited a much-improved conversion efficiency with charge carrier mobility 1000 times higher than that of pristine film, as well as showed robust stability under various harsh conditions.

Ionic and poly(ionic liquid)s as perovskite passivating molecules for improved solar cell performances

Ionic liquids and poly(ionic liquid)s act as bulk and/or passivation agents when used as additives in methylammonium-free lead perovskites, leading to devices showing enhanced power conversion efficiencies, reduced hysteresis and improved stability.

Synthesis and characterization of thermally-evaporated CdS thin-films

Cadmium sulfide (CdS) thin films (thickness: 200 nm) were grown over silicon (Si) substrate via thermal evaporation deposition method, where the ultimate pressure and deposition rate were 1 × 10−6 torr and 1.0-1.2 Å/sec, respectively. X-ray diffraction established polycrystalline films with a hexagonal crystal structure and preferred orientation (002). The energy dispersive analysis of X-ray has recognized pure and stoichiometric films. The uniform, dense and smooth films with low roughness (1.4 nm) appeared in atomic force microscopy. The scanning electron microscopy characterization has recognized a continuous and defects-free film (like cracks, pinholes and overhang) with a uniform distribution of interconnected nanoparticles (size: 24.5–35.1 nm). The good adhesion of the film was confirmed via a scotch tape test. Ellipsometry revealed that the grown CdS film has a refractive index of 2.42–2.45. Thus, polycrystalline CdS film with hexagonal phase (highly stable, wide bandgap, high transmission, environmentally tolerable, and good mechanical strength) could be utilized as a suitable window material and passivation agent in the fabrication of solar cell and infrared detector, respectively.

Facile green synthesis of fluorescent carbon nanoparticles using spider silks

Carbon nanoparticles (CNPs) have emerged as a promising candidate because of their interesting properties. They can be synthesized by chemical method as well as through green chemistry. Herein, we report a green synthesis approach for the CNPs from spider silk by pyrolysis at temperature 400°C without using any carbonizing or passivating agent. The structural and optical properties of the synthesized CNPs have been characterized by using X-Ray diffraction (XRD), Raman spectroscopy, SEM (scanning electron microscope) - Energy Dispersive X-Ray (EDAX) analysis, UV – Visible and photoluminescence (PL) spectroscopy. The results obtained show that prepared carbon nanoparticles (CNPs) have a great potential for bio-sensing, bio-imaging, disease diagnosis, and other different optoelectronic device applications.

Surface-Passivated CsPbBr3 for Developing Efficient and Stable Perovskite Photovoltaics

All-inorganic perovskites consisting of only inorganic elements have been recently considered as highly stable semiconductors for photoactive layer of optoelectronics applications. However, the formation of high-quality thin film and trap-reduced interface has still remains an important task, which should be solved for improving the performances of all-inorganic perovskite-based photovoltaics. Here, we adopted facile method that could reduce charge-carrier recombination by depositing a passivation agent on the top surface of the CsPbBr3 all-inorganic perovskite layer. We also found that the CsPbBr3 perovskite photovoltaic prepared from surface treatment method using n-octylammonium bromide provides an improved stability in ambient environment and 1-sun illuminating condition. Therefore, the perovskite photovoltaics fabricated from our approach offered an improved power conversion efficiency of 5.44% over that of the control device without surface treatment (4.12%).

Monodisperse Carbon Nitride Nanosheets as Multifunctional Additives for Efficient and Durable Perovskite Solar Cells.

Two-dimensional (2D) materials are promising components for defect passivation of metal halide perovskites. Unfortunately, commonly used polydisperse liquid-exfoliated 2D materials generally suffer from heterogeneous structures and properties while incorporated into perovskite films. We introduce monodisperse multifunctional 2D crystalline carbon nitride, poly(triazine imide) (PTI), as an effective defect passivation agent in perovskite films via typical solution processing. Incorporation of PTI into perovskite film can be readily attained by simple solution mixing of PTI dispersions with perovskite precursor solutions, resulting in the highly selective distribution of PTI localized at the defective crystal grain boundaries and layer interfaces in the functional perovskite layer. Several chemical, optical, and electronic characterizations, in conjunction with density functional theory calculations, reveal multiple beneficial roles from PTI: passivation of undercoordinated organic cations at the surface of perovskite crystal, suppression of ion migration by blocking diffusion channels, and prevention of hole quenching at perovskite/SnO2 interfaces. Consequently, a noticeably improved power conversion efficiency is achieved in perovskite solar cells, accompanied with promoted stability under humid air and thermal stress. Our strategy highlights the potential of judiciously designed 2D materials as a simple-to-implement material for various optoelectronic devices, including solar cells, based on hybrid perovskites.

Studies of Surface Preparation for the Fluorosequencing of Peptides.

Silica passivating agents have shown great success in minimizing nonspecific protein binding to glass surfaces for imaging and microscopy applications. Amine-derivatized surfaces are commonly used in conjugation with amide coupling agents to immobilize peptides/proteins through C-terminal or side-chain carboxylic acids. In the case of the single-molecule fluorosequencing of peptides, attachment occurs via the C-terminus and nonspecific surface binding has previously been a source of error in peptide identification. Here, we employ fluorosequencing as a high-throughput, single-molecule sensitivity assay to identify and quantify the extent of nonspecific binding of peptides to amine-derivatized surfaces. We show that there is little improvement when using common passivating agents in combination with the surface derivatizing agent 3-aminopropyl-triethoxysilane (APTES) to couple the peptides to the modified surface. Furthermore, many xanthene fluorophores have carboxylic acids in the appended phenyl ring at positions ortho and meta or ortho and para, and the literature shows that conjugation through the ortho position is not favored. Because xanthene-derived fluorophores are commonly used for single-molecule applications, we devised a novel assay to probe the conjugation of peptides via their fluorophores relative to their C-termini on silane-derivatized surfaces. We find significant attachment to the ortho position, which is a warning to those attempting to immobilize fluorophore-labeled peptides to silica surfaces via amide coupling agents. However, eliminating all amines on the surface by switching to 3-azidopropyl-triethoxysilane (AzTES) for coupling via copper-catalyzed azide-alkyne cycloaddition (CuAAC) and omitting additional passivation agents allowed us to achieve a high level of C-terminally bound peptides relative to nonspecifically or ortho-phenyl-bound, fluorophore-labeled peptides. This strategy substantially improves the specificity of peptide immobilization for single-molecule fluorosequencing experiments.

On the role of carboxylated polythiophene in defect passivation of CsPbI 2 Br surface for efficient and stable all‐inorganic perovskite solar cells

Improved film surface is a prerequisite to achieve high photovoltaic performance of inorganic perovskite solar cells because defective (under-coordinated) lead ions derived from imperfect lattice structure of the film surface or grain boundaries the principal nonradiative recombination centers in the inorganic perovskite absorber. In this study, we suggest poly[3-(4-carboxybutyl)thiophene-2,5-diyl] (P3CT), a carboxylated p-type conjugated polymer, as a passivating agent of the CsPbI2Br layer to tailor electronic properties of a perovskite absorber. With the P3CT passivation, the defective sites of the perovskite film surface were improved and stabilized, which can suppress nonradiative recombination to promote charge transport of CsPbI2Br-based all-inorganic perovskite solar cells. Consequently, the P3CT passivation delivers a power conversion efficiency (PCE) of 12.25% and decent long-term stability of CsPbI2Br perovskite solar cells, which surpasses the pristine device without the passivation. The electricity generation capability under indoor light source of the passivated device is also studied, demonstrating a promising PCE of 27.47%. This work unveils the role of P3CT as a passivating agent to passivate the defective sites of CsPbI2Br perovskite film surface and grain boundaries, which facilitates charge transport and reduced carrier recombination of CsPbI2Br absorber in solar cell devices.

Green synthesis of silver nanoparticles using aqueous extract of Citrus sinensis peels and evaluation of their antibacterial efficacy

Abstract The resistance of microorganisms towards antibiotics remains a big challenge in medicine. Silver nanoparticles (AgNPs) received attention recently for their characteristic nanosized features and their ability to display antimicrobial activities. This work reports the synthesis of AgNPs using the Citrus sinensis peels extract in their aqueous, mild, and less hazardous conditions. The effect of concentration variation (1%, 2%, and 3%) of the plant extracts on the size and shape of the AgNPs was investigated. The antimicrobial activities were tested against gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae. Absorption spectra confirmed the synthesis by the surface Plasmon resonance peaks in the range 400–450 nm for all the AgNPs. FTIR spectra confirmed that Citrus sinensis peels extract acted as both reducing and surface passivating agent for the synthesized AgNPs. TEM revealed spherical AgNPs with average size of 12 nm for 3% concentration as compared to the agglomeration at 1% and 2%. All the AgNPs synthesized using Citrus sinensis peels extracts (1%, 2%, and 3%) exhibited antimicrobial activity against both gram-positive and negative bacteria. These results indicated a simple, fast, and inexpensive synthesis of silver nanoparticles using the Citrus sinensis peels extract that has promising antibacterial activity.

Enhanced Activation Energy Released by Coordination of Bifunctional Lewis Base d-Tryptophan for Highly Efficient and Stable Perovskite Solar Cells.

Perovskite defect passivation with molecule doping shows great potential in boosting the efficiency and stability of perovskite solar cells (PSCs). Herein, an efficient and low-cost bifunctional Lewis base additive d-tryptophan is introduced to control the crystallization and growth of perovskite grains and passivation defects. It is found that the additive doped in the solution precursors could retard crystal growth by increasing activation energy, resulting in improved crystallization of large grains with reduced grain boundaries, as well as inhibiting ion migration and PbI2 aggregation. As a result, the PSCs incorporated with d-tryptophan additives achieve an improved power conversion efficiency from 18.18 to 21.55%. Moreover, the d-tryptophan passivation agent improves the device stability, which retains 86.85% of its initial efficiency under ambient conditions at room temperature after 500 h. This work provides Lewis base small-molecule d-tryptophan for efficient defect passivation of the grain boundaries toward efficient and stable PSCs.

Quinary Nanocrystal‐Based Passivation Strategy for High Efficiency and Stable Perovskite Photovoltaics

Despite the rapid progress of perovskite materials in emerging perovskite photovoltaic devices, they still suffer from the polycrystalline nature associated with grain boundaries (GBs) which are vulnerable to moisture permeation and/or ion migration. Besides, charge carrier recombination of GBs through defect states plays a crucial role in restricting the performance and stability of perovskite photovoltaics. To address such detrimental issues, quinary kesterite nanocrystals, namely Cu2NiSn(S,Se)4 (CNTSSe), having narrow size distribution below 10 nm by a facile hot‐casting method are rationally designed and employed as a passivation agent for the GBs/surface of perovskite films. This passivation strategy greatly reduces defect states at perovskite GBs and promotes continuity between adjacent grains, resulting in accelerated hole transport ability and suppressed interfacial recombination. Thereupon, champion power conversion efficiency of 20.8% (20.5 ± 0.3% in average) (Cs0.05(FA0.90MA0.10)0.95Pb(I0.90Br0.10)3), 18.9% (MAPbI3), and 18.7% (FAPbI3) is achieved with a negligible hysteresis and outstanding stability by retaining over 85% of initial performance under ambient conditions with continuous illumination over 900 h. Herein, not only a universal approach to effectively passivate the GBs of the perovskite films by inorganic nanocrystals is presented, but also a deep understanding of detrimental defects on the photovoltaic performance and stability of perovskite solar cells is ensured.

High performance sky-blue perovskite light-emitting diodes enabled by a bifunctional phosphate molecule

Defects such as uncoordinated lead ions and surface charged defects are still one of critical issues for perovskite light-emitting diodes (PeLEDs). The presence of these defects can trap excitons, resulting in enhanced nonradiative recombination and thus poor efficiencies of PeLEDs. Defect passivation via passivation agents is an effective way to solve this issue. In this work, we introduce a bifunctional phosphate molecule 6,6′-(ethane-1,2-diyl)bis(dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (DIDOPO) as a passivation agent into the perovskite, where DIDOPO can bind with the perovskite via the chemical interaction between the PO groups and uncoordinated Pb ions. Thus, the incorporation of DIDOPO effectively passivates the defects, leading to improved radiative recombination. Simultaneously, the as-prepared perovskite film produces dense and smooth morphology, which is favorable to good contact with the adjacent charge transport layers and the reduction of leakage current. As a result, the sky-blue PeLEDs modified by DIDOPO show improved efficiency with the maximum external quantum efficiency (EQEmax) of 5.52% and the average EQEmax of 5.09%. Furthermore, attributed to the alkyl chain as the bridge between the phosphate groups, DIDOPO accumulated at the perovskite surface is able to decrease hydrophilic behavior of the perovskite. The PeLEDs containing DIDOPO possess enhanced moisture resistance, remaining ca. 91–92% of the initial EQE after storage for 120 h in ambient atmosphere with the humidity of ca. 40%.

Multifunctional passivation agents for improving efficiency and stability of perovskite solar cells: Synergy of methyl and carbonyl groups

Recently, the incorporation of passivation agents to reduce perovskite recombination has been proven to be one of the best approaches to achieving high-performance perovskite solar cells (PeSCs). Although several passivation compounds have been discovered, the mechanisms of passivation in diverse functional groups remain a mystery. In this work, we design bi-functional passivation agents, including methyl and carboxyl groups, as well as multi-functional passivation agent structures, including both methyl and carboxyl groups, and then we systematically study their passivation- and crystallinity control-abilities for PeSCs. Through electrostatic interactions with perovskite precursors, bi-functional passivation agents combined with piperidine ring and methyl (CH3) can passivate defects, and the carboxyl group (C = O) can increase the grain size and reduce the grain boundaries. Importantly, different functional groups, such as COCH3 groups comprising piperidine rings, CH3, and C = O, further improved the defect passivation effect. As the interaction between Pb2+ and COCH3 increased, the slow nuclear growth process of perovskite films introducing COCH3 increased the film quality and their charge extraction/collection capability, thus resulting in a PCE of 19.67%. In addition, the COCH3-based PesC's VOC and long-term stability are substantially enhanced.

Use of Polyhedral Oligomeric Silsesquioxane (POSS) in Drug Delivery, Photodynamic Therapy and Bioimaging.

Polyhedral oligomeric silsesquioxanes (POSS) have attracted considerable attention in the design of novel organic-inorganic hybrid materials with high performance capabilities. Features such as their well-defined nanoscale structure, chemical tunability, and biocompatibility make POSS an ideal building block to fabricate hybrid materials for biomedical applications. This review highlights recent advances in the application of POSS-based hybrid materials, with particular emphasis on drug delivery, photodynamic therapy and bioimaging. The design and synthesis of POSS-based materials is described, along with the current methods for controlling their chemical functionalization for biomedical applications. We summarize the advantages of using POSS for several drug delivery applications. We also describe the current progress on using POSS-based materials to improve photodynamic therapies. The use of POSS for delivery of contrast agents or as a passivating agent for nanoprobes is also summarized. We envision that POSS-based hybrid materials have great potential for a variety of biomedical applications including drug delivery, photodynamic therapy and bioimaging.

Interface States Passivation for p-Channel 4H-SiC MOS Devices

Impressive material properties such as wide band gap, high breakdown electric field and thermal conductivity makes silicon carbide (4H-SiC) an attractive semiconductor for high power and high temperature electronics. Applications include, but are not limited to, power and control systems in hybrid and electric vehicles, space crafts and renewable energy sources [1-2]. In addition to discrete power components, an advanced 4H-SiC complementary metal-oxide-semiconductor (CMOS) integrated circuit technology has the potential to revolutionize high temperature electronics, for operational temperatures greater than 200 ºC [3-4], where Si is not efficient or usable. CMOS requires both n-channel (electron) and p-channel (hole) metal-oxide-semiconductor field effect transistors (MOSFETs) and it is critical for both polarities to have adequate performance. In n-channel 4H-SiC devices, nitrogen incorporation at the SiO2/4H-SiC interface reduces interface state density (Dit) energetically located in the upper half of the 4H-SiC band gap and near the conduction band-edge [5]. Research on p-channel is less extensive, but prior research motivates hydrogen [6] and more recent studies suggest nitrogen [7] as effective passivation agents for donor like traps in the lower half of the 4H-SiC band gap. In this work, we investigated several post-oxidation annealing (POA) processes involving nitrogen and hydrogen for Dit reduction in p-type MOS capacitors. For a comparative study, n-type capacitors were also fabricated and characterized. All samples were oxidized at 1150 °C to grow a ~60 nm oxide film and some samples were subjected to POA as summarized in Table 1. The results show that NO and H2 both reduce Dit in the lower half of the 4H-SiC band gap, with NO having a much larger effect. The reduction of positive trapped charge lowers the flat band voltage for p-type 4H-SiC MOS capacitors with different degrees of passivation as shown in Figure 1. The Dit profile near the band-edges, extracted from simultaneous high (100 kHz) - low frequency CV at room temperature, highlights the large reduction associated with NO, as shown in Figure 2. The effect of hydrogen is primarily in the reduction of energetically deep interface traps. To measure the density of the deep traps (Nit, deep), photon assisted CV measurements [8] were carried out, from which Nit, deep was calculated as shown in Figure 3 and summarized in Table 1. Overall, the results confirmed that 2 hour NO annealing at 1175 °C results in the lowest Dit in the lower half of the band gap. Longer NO annealing times or combination of NO with hydrogen resulted in higher Nit, deep as listed in Table 1. Therefore, long channel 4H-SiC p-MOSFETs were fabricated using the 2 hour NO POA process to investigate hole transport and gate control in devices operating at high temperature. The results from the transfer characteristics in Figure 4 indicate that with the increase of temperature, threshold voltage reduces which can be attributed to the reduction of occupied Dit at higher temperatures. A weak temperature dependence of the hole field effect mobility with temperature is present most likely due to surface roughness scattering limitations at higher channel hole concentrations. In this presentation, the field-effect mobility will be compared to Hall measurements for additional insights into surface hole transport. In addition, details of the CV analyses, FET fabrication procedure and high temperature bias instability will be discussed. Acknowledgements: The authors gratefully acknowledge the funding support from US Army Research Laboratory grant ARMY-W911NF-18-2-0160 and National Renewable Energy Laboratory/ US Department of Energy grant NREL-AHL-9-92362-01. References : [1] S. Srdic et al., IEEE Appl. Power Elec. Conf. and Expo.(APEC), 2714 (2016)[2] M. Abbasi et al., in IEEE Trans. Emerg. Sel. Topics Power Electron., 7, 798 (2019)[3]A. M. Francis et al., Proc. IMAPS High Temperature Electron. Conf., 2016, 242, (2016)[4] A. S. Kashyap et al., IEEE (WiPDA), 60 (2013)[5] G. Liu et al. Appl. Phys. Rev. 2, 021307 (2015)[6] M. Okamoto et al. Appl. Phys. Lett., 89, 023502 (2006)[7] K. Tachiki and T. Kimoto IEEE Trans. Elec. Dev., 68, 638 (2021)[8] J. A. Cooper, Jr., phys. stat. sol. 162, 305 (1997) Figure 1

Green synthesis of Spirulina-based carbon dots for stimulating agricultural plant growth

In this study, photoluminescent carbon quantum dots (CQDs) were synthesized by thermal pyrolysis of the microalgae spirulina without any surface passivating agent. The CQDs showed ~10 nm average size and exhibited blue photoluminescence emission around 450 nm under 340–400 nm excitation wavelength. A quantum yield of 23.5% was attained at 300 °C for 2 h. Thermodynamic and kinetic investigations about pyrolysis reaction showed that CQDs synthesis occurs slowly and non-spontaneously, with a mean activation energy of 192.6 kJ/mol. The final product showed a broad range of solubility, besides being efficient for lentil seed growth when dispersed in 0.05–0.1 mg/mL aqueous solutions. The CQDs reported here may be considered a promising renewable bio-based fertilizer for crop species in the sustainable agriculture field.

Interfacial modification of perovskite solar cells via Cs2CO3: Computational and experimental approach

Interfacial materials in perovskite solar cells (PSCs) between the absorber layer and charge selective layers are stimulants to boost performance and stability. Incorporation of a low-temperature processed passivating agent at electron selective layer/perovskite interface can enhance the performance of PSCs; however, the interface at SnO2/(FAPbI3)0.85(MAPbBr3)0.15 suffers from surface phenomena that retard the overall performance of the PSCs. By adopting a synergistic approach, drift–diffusion simulation, and experimental validation, we unravel the interaction of the passivation layer at the electron selective layer/perovskite. Firstly, we elucidated the impact of defect density (Nt) at electron selective layer/perovskite and the conduction band of SnO2 using drift–diffusion simulation to yield a power conversion efficiency of 23.18 %. Secondly, we validate the simulation trend experimentally by depositing the Cs2CO3 passivation layer on the top of the electron selective layer. The impact of Cs2CO3 on electro-optical properties, charge collection, and recombination rate at the interfaces of PSCs was unraveled. The PSC fabricated with Cs2CO3 treatment achieves a higher open-circuit voltage, Voc ∼ 1090 mV. Our findings put forward a combinatorial protocol of drift–diffusion simulation and experimental studies to address the interfacial issues in PSCs.

Defect Passivation for Perovskite Solar Cells: from Molecule Design to Device Performance.

Perovskite solar cells (PSCs) are a promising third-generation photovoltaic (PV) technology developed rapidly in recent years. Further improvement of their power conversion efficiency is focusing on reducing the non-radiative charge recombination induced by the defects in metal halide perovskites. So far, defect passivation by the organic small molecule has been considered as a promising approach for boosting the PSC performance owing to their large structure flexibility adapting to passivating variable kinds of defect states and perovskite compositions. Here, the recent progress of defect passivation toward efficient and stable PSCs was reviewed from the viewpoint of molecular structure design and device performance. To comprehensively reveal the structure-performance correlation of passivation molecules, it was separately discussed how the functional groups, organic frameworks, and side chains affect the corresponding PV parameters of PSCs. Finally, a guideline was provided for researchers to select more suitable passivation agents, and a perspective was given on future trends in development of passivation strategies.