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[Display omitted] • SAM-NH 2 improves interfacial thermal conductance by 140% in EP/Si systems. • Bilateral covalent bonds enhance interfacial adhesion and phonon matching. • Interfacial adhesion strength can improve interfacial heat transport. • Single side covalent bond may reduce interface heat transport. Epoxy resin (EP) based composite materials, due to their advantages such as light weight, ease of processing, and mechanical properties, have been widely applied across thermal packaging field. However, the overall thermal conductivity is constrained by the interfacial thermal resistance between the filler and the substrate. Existing studies suggest that self-assembled monolayers (SAM) can enhance the interfacial thermal conductance (ITC) by forming covalent bonds. Nevertheless, limited research has focused on using SAM to form bilateral covalent bonds to regulate ITC. Therefore, SAM capable of forming bilateral covalent bonds at the EP/silicon (Si) interface were employed to enhance ITC. In this study, time-domain thermoreflectance (TDTR) experiments and molecular dynamics (MD) simulations were conducted to investigate the EP/SAM/Si system. The results demonstrate that SAM-NH 2 modification, which forms bilateral covalent bonds at the EP/Si interface, increased the interfacial adhesion strength and enhanced ITC to 140%, thereby significantly promoting interfacial heat transfer. Conversely, ITC was reduced with SAM-CH 3 due to the formation of single covalent bond. Subsequently, the differential effective medium (DEM) model was used to determine that the thermal conductivity of the composite modified with SAM-NH 2 was improved by 11%. This study provides new insights into adjusting ITC using SAM. [ABSTRACT FROM AUTHOR]

Prof. George Whitesides' pioneering contributions to the field of self-assembled monolayers (SAMs) have profoundly influenced biointerface science and beyond. This review explores the development of SAMs as highly organized molecular structures, focusing on their role in advancing surface science, biointerface research, and biomedical applications. Prof. Whitesides' systematic investigations into the effects of SAMs' terminal group chemistries on protein adsorption and cell behavior culminated in formulating "Whitesides' Rules", which provide essential guidelines for designing bioinert surfaces. These principles have driven innovations in anti-fouling coatings for medical devices, diagnostics, and other biotechnological applications. We also discuss the critical role of interfacial water in SAM bioinertness, with studies demonstrating its function as a physical barrier preventing protein and cell adhesion. Furthermore, this review highlights how data science and machine learning have expanded the scope of SAM research, enabling predictive models for bioinert surface design. Remarkably, Whitesides' Rules have proven applicable not only to SAMs but also to polymer-brush films, illustrating their broad relevance. Prof. Whitesides' work provides a framework for interdisciplinary advancements in material science, bioengineering, and beyond. The enduring legacy of his contributions continues to inspire innovative approaches to addressing challenges in biomedicine and biotechnology. [ABSTRACT FROM AUTHOR]

Area-selective atomic layer deposition (AS-ALD) is a technique utilized for the fabrication of patterned thin films in the semiconductor industry due to its capability to produce uniform and conformal structures with control over thickness at the atomic scale level. In AS-ALD, surfaces are functionalized such that only specific locations exhibit ALD growth, thus leading to spatial selectivity. Self-assembled monolayers (SAMs) are commonly used as ALD inhibiting agents for AS-ALD. However, the choice of organic molecules as viable options for AS-ALD remains limited and the precise effects of ALD nucleation and exposure to ALD conditions on the structure of SAMs is yet to be fully understood. In this work, we investigate the potential of small molecule carboxylates as ALD inhibitors, namely benzoic acid and two of its derivatives, 4-trifluoromethyl benzoic acid (TBA), and 3,5-Bis (trifluoromethyl)benzoic acid (BTBA) and demonstrate that monolayers of all three molecules are viable options for applications in ALD blocking. We find that the fluorinated SAMs are better ALD inhibitors; however, this property arises not from the hydrophobicity but the coordination chemistry of the SAM. Using nanoscale infrared spectroscopy, we probe the buried monolayer interface to demonstrate that the distribution of carboxylate coordination states and their evolution is correlated with ALD growth, highlighting the importance of the interfacial chemistry in optimizing and assessing ALD inhibitors. [ABSTRACT FROM AUTHOR]

Polymeric hole‐selective materials (P‐HSMs) offer advantages like solution processability, tunable energy levels, and improved mechanical stability, making them suitable for large‐scale and flexible substrates. Poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] (PTAA) based p–i–n perovskite solar cells exhibit promising power conversion efficiency (PCE), but wettability, dopant, and cost challenges necessitate the development of advanced next‐generation P‐HSMs. To provide a clear understanding of the structural property with photovoltaic performance, this review classifies such newly developed P‐HSMs into five distinct structural categories. Specifically, this review discusses the current status, advancements, challenges, and prospects in structural design and synthetic variations, focusing on enhancing photovoltaic performance, wettability, mitigating surface defects, and stability. Notably, incorporating polar units into P‐HSMs enhances wettability and mitigates ion instabilities and uncoordinated lead defects. Promising structural designs like polymeric self‐assembled monolayers and in situ polymerized hole‐selective materials are examined. Despite performance advancements, emerging, P‐HSMs face significant challenges such as limited thermal stress analysis (55–85 °C) and scalability restricted to small‐scale devices. To bridge this gap, this review emphasizes the urgent need for prioritizing thermal stability testing and large‐scale device fabrication in future research, paving the way for commercial viability of P‐HSMs in p–i–n perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

The effect of solution pH on the formation and surface structure of 2-pyrazinethiolate (2-PyzS) self-assembled monolayers (SAMs) formed by the adsorption of 2-mercaptopyrazine (2-PyzSH) on Au(111) was investigated using scanning tunneling microscopy (STM) and X-ray photoelectron microscopy (XPS). Molecular-scale STM observations clearly revealed that 2-PyzS SAMs at pH 2 had a short-range ordered phase of (2√3 × √21)R30° structure with a standing-up adsorption structure. However, 2-PyzS SAMs at pH 8 had a very unique long-range ordered phase, showing a "ladder-like molecular arrangement" with bright repeating rows. This ordered phase was assigned to the (3 × √37)R43° structure, consisting of two different adsorption structures: standing-up and tilted adsorption structures. The average arial density of 2-PyzS SAMs on Au(111) at pH 8 was calculated to be 49.47 Å2/molecule, which is 1.52 times more loosely packed compared to the SAMs at pH 2 with 32.55 Å2/molecule. XPS measurements showed that 2-PyzS SAMs at pH 2 and pH 8 were mainly formed through chemical interactions between the sulfur anchoring group and the Au(111) substrates. The proposed structural models of packing structures for 2-PyzS SAMs on Au(111) at different pHs are well supported by the XPS results. The results of this study will provide new insights into the formation, surface structure, and molecular orientation of SAMs by N-heteroaromatic thiols with pyrazine molecular backbone on Au(111) at the molecular level. [ABSTRACT FROM AUTHOR]

Great efforts have been made to improve the composition and structure of perovskite light‐emitting diodes (PeLEDs) through methods such as dimensional reduction or halide engineering, thereby reducing non‐radiative recombination. However, deep‐blue PeLEDs still face a deep valence band issue. The mismatched energy level alignment between the perovskite and the hole transport layer (HTL) leads to charge accumulation, resulting in imbalanced carrier transport and injection. Herein, to address the issues of imbalanced carrier injection and defect states in PeLEDs, a deep‐blue perovskite emitter using [4‐(3,6‐Dimethyl‐9H‐carbazol‐9‐yl)butyl]phosphonic acid (Me‐4PACz) as the material to promote hole transport and passivate defects is presented. The stepwise energy level structure design can effectively reduce the hole injection barrier and improve the carrier injection efficiency. Additionally, the electron‐rich P═O bond can effectively passivate the unsaturated Pb2+ in perovskite, reducing non‐radiative recombination caused by defects. Ultimately, stable deep‐blue PeLEDs (≈458 nm) are successfully fabricated with an external quantum efficiency (EQE) of 4.33%. This study provides new insights into the application of self‐assembled monolayers (SAMs) in PeLEDs. [ABSTRACT FROM AUTHOR]

Inverted perovskite solar cells (PSCs) have gained great attention owing to their advantageous low-temperature preparation processes, high operational stability and compatibility with tandem solar cell architectures. The integration of self-assembled monolayers (SAMs) as effective hole-selective contacts in inverted PSCs has contributed to incredible advancements in device performance. In this review, we first discuss the structure and characteristics of the SAM molecules and then give an overall understanding of the bonding mechanism between SAMs and the substrate, as well as the preparation methods for SAMs. Besides, the advances of SAM-based inverted PSCs have been introduced in terms of energy band alignment and interfacial passivation and cost-effectiveness. Finally, the current issues associated with SAMs in inverted PSCs and the corresponding strategies to overcome those limitations are discussed. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of inverted perovskite solar cells (PSCs) relies on effectively managing the interface between the hole extraction layer and the light‐absorbing perovskite layer. In this study, we have synthesised (4‐(3,6‐bis(methylthio)‐9H‐carbazol‐9‐yl)butyl)phosphonic acid (MeS‐4PACz), which forms a self‐assembled monolayer (SAM) on the fluorine‐doped tin oxide (FTO) electrode. The molecule‘s methylthio substituents generate a favourable interfacial dipole moment and interact with the perovskite layer. This interaction results in well‐aligned energy levels among the FTO/SAM/perovskite layers, promoting efficient hole extraction and significantly reducing carrier recombination losses. Additionally, the methylthio groups passivate iodide vacancies and interact with Pb2+ ions of the perovskite, reducing defect‐induced trap states and enhancing the crystalline growth of the perovskite layer. Consequently, inverted PSCs incorporating MeS‐4PACz achieve a power conversion efficiency of 25.13 %, along with outstanding photostability. [ABSTRACT FROM AUTHOR]

Aromatic linker‐constructed self‐assembled monolayers (Ar‐SAMs) with enlarged dipole moment can modulate the work function of indium tin oxide (ITO), thereby improving hole extraction/transport efficiency. However, the specific role of the aromatic linkers between the polycyclic head and the anchoring groups of SAMs in determining the performance of perovskite solar cells (PSCs) remains unclear. In this study, we developed a series of phenothiazine‐based Ar‐SAMs to investigate how different aromatic linkers could affect molecular stacking, the regulation of substrate work function, and charge carrier dynamics. When served as hole‐selective layers (HSLs) in PSCs and monolithic perovskite/silicon tandem solar cells (P/S‐TSCs), we found that the Ar‐SAM with naphthalene linker along the 2,6‐position axis (β‐Nap) could form dense and highly ordered HSLs, enhancing interfacial interactions and favoring optimal energy level alignment with the perovskite films. Using this strategy, the optimized wide‐band gap PSCs achieved an impressive power conversion efficiency (PCE) of 21.86 % with negligible hysteresis, utilizing a 1.68 eV perovskite. Additionally, the encapsulated devices demonstrated enhanced stability under damp‐heat conditions (ISOS‐D‐2, 50 % RH, 65 °C) with a T91 of 1000 hours. Notably, the fabricated P/S‐TSCs, based on solution‐processed micron‐scale textured silicon heterojunction (SHJ) solar cells, achieved an efficiency of 28.89 % while maintaining outstanding reproducibility. This strategy holds significant promise for developing aromatic linking groups to enhance the hole selectivity of SAMs. [ABSTRACT FROM AUTHOR]

In recent years, self‐assembled monolayers (SAMs) anchored on metal oxides (MO) have greatly boosted the performance of inverted (p‐i‐n) perovskite solar cells (PVSCs) by serving as hole‐selective contacts due to their distinct advantages in transparency, hole‐selectivity, passivation, cost‐effectiveness, and processing efficiency. While the intrinsic monolayer nature of SAMs provides unique advantages, it also makes them highly sensitive to external pressure, posing a significant challenge for long‐term device stability. At present, the stability issue of SAM‐based PVSCs is gradually attracting attention. In this minireview, we discuss the fundamental stability issues arising from the structural characteristics, operating mechanisms, and roles of SAMs, and highlight representative works on improving their stability. We identify the buried interface stability concerns in three key aspects: 1) SAM/MO interface, 2) SAM inner layer, and 3) SAM/perovskite interface, corresponding to the anchoring group, linker group, and terminal group in the SAMs, respectively. Finally, we have proposed potential strategies for achieving excellent stability in SAM‐based buried interfaces, particularly for large‐scale and flexible applications. We believe this review will deepen understanding of the relationship between SAM structure and their device performance, thereby facilitating the design of novel SAMs and advancing their eventual commercialization in high‐efficiency and stable inverted PVSCs. [ABSTRACT FROM AUTHOR]

The strategy of incorporating self‐assembled monolayers (SAMs) with anchoring groups is an effective and promising method for interface engineering in perovskite solar cells with metal oxide charge‐transporting layers. However, coating SAM layers in upscaled perovskite solar modules (PSMs) using slot‐die coating is challenging due to the low viscosity and wettability of the solutions. In this study, a triphenylamine‐based polymer poly([{5‐[4‐(diphenylamino)phenyl]‐2‐thienyl}(4‐fluorophenyl)methylene]malononitrile) (pTPA)–TDP, blended with SAM based on 5‐[4‐[4‐(diphenylamino)phenyl]thiophene‐2‐carboxylic acid, is integrated to address these challenges. And, p–i–n‐oriented PSMs on 50 × 50 mm2 substrates (12 sub‐cells) are fabricated with a NiO hole‐transport layer and organic interlayers for surface modification. Wetting angle mapping shows that ununiform regions of the slot‐die‐coated SAM has extreme hydrophobicity, causing absorber thickness fluctuations and macro‐defects at buried interfaces. The blended interlayer at the NiO/perovskite junction homogenizes surface wettability and mitigates lattice strain, enabling the effective use of SAM properties on large surfaces. This improved energy level alignment, enhancing the power conversion efficiency of the modules from 13.98% to 15.83% and stability (ISOS‐L‐2, T80 period) from 500 to 1630 h. In these results, the complex effects of using SAM in slot‐die‐coating technology for large‐scale perovskite photovoltaics are highlighted. [ABSTRACT FROM AUTHOR]

The antisolvent‐assisted spin‐coating still lags behind the thermal evaporation method in fabricating perovskite films atop industrially textured silicon wafers in making monolithic perovskite/silicon solar cells (P/S‐TSCs). The inhomogeneity of hole‐selective self‐assembled monolayers (SAMs) often arises from the insufficient bonding between hygroscopic phosphonic acid anchors and metal oxide. To address this, a mixed‐SAM strategy (Mx‐SAM) is proposed to enhance the adsorption energy of SAMs on the ITO surface, facilitate the formation of dense and humidity‐resistant hole‐selective layer (HSL) on substrates, and improve hole transport capabilities. With the aid of the Mx‐SAM strategy, the optimized wide‐bandgap PSCs achieved an impressive power conversion efficiency (PCE) of 22.63% with an exceptionally high fill factor (FF) of 86.67% using the 1.68 eV perovskite. Moreover, they exhibited enhanced stability under damp‐heat conditions (ISOS‐D‐3, 85% RH, 85 °C) with a T90 of 900 h for encapsulated PSCs, representing one of the best performances for wide‐bandgap PSCs. When further extending the Mx‐SAM strategy to making P/S‐TSCs using silicon wafers from industry, a remarkable efficiency of 28.07% is reached while upholding outstanding reproducibility. This strategy holds significant promise for the feasibility of fabricating industrially‐compatible P/S‐TSCs. [ABSTRACT FROM AUTHOR]

P‐type carbazole‐derived self‐assembled monolayers (SAMs) have garnered significant attention as promising hole transport layers (HTLs) in the development of highly efficient organic solar cells (OSCs). However, it still lacks the effective navigation to modulate the terminal functional groups of SAMs to achieve a compromise between the highest occupied molecular orbital (HOMO) energy levels and self‐aggregation behavior. Herein, the terminal functional groups are adjusted and three SAMs are synthesized, namely, t‐Bu‐3PACz, Ph‐3PACz, and Bz‐3PACz to comprehensively investigate their intrinsic properties and influence on photovoltaic performance. Among them, Ph‐3PACz featuring an exceptionally suitable conjugated region and steric hindrance exhibits the best compatibility with the active layer, superior electrical conductivity, HOMO energy level aligning with polymer donor, and ordered film packing. As a result, the photovoltaic devices based on Ph‐3PACz exhibit an open‐circuit voltage (VOC) of 0.850 V, a short‐circuit current density (JSC) of 28.7 mA cm−2, and a fill factor (FF) of 78.5%, thus resulting in a remarkable power conversion efficiency (PCE) of 19.2%. This work provides an effective and easily navigable method to modulate the molecular packing and energy levels of SAMs, thereby achieving highly efficient OSCs. [ABSTRACT FROM AUTHOR]

Voltage-responsive biosensors capable of monitoring real-time adsorption behavior of biological analytes onto electroactive surfaces offer attractive strategies for disease detection, separations, and other adsorption-dependent analytical techniques. Adsorption of biological analytes onto electrically switchable surfaces can be modelled using neutravidin and biotin. Here, we report self-assembled monolayers formed from voltage-switchable biotinylated molecules on gold surfaces with tunable sensitivity to neutravidin in response to applied voltages. By using electrochemical quartz crystal microbalance (EQCM), we demonstrated real-time switchable behavior of these bio-surfaces and investigate the range of sensitivity by varying the potential of the same surfaces from −400 mV to open circuit potential (+155 mV) to +300 mV. We compared the tunability of the mixed surfaces to bare Au surfaces, voltage inert surfaces, and switchable biotinylated surfaces. Our results indicate that quartz crystal microbalance allows real-time changes in analyte binding behavior, which enabled observing the evolution of neutravidin sensitivity as the applied voltage was shifted. EQCM could in principle be used in kinetic studies or to optimize voltage-switchable surfaces in adsorption-based diagnostics. [ABSTRACT FROM AUTHOR]

This study aims to improve our understanding of some differences in odd and even chain-length alkanethiol self-assembled monolayers (SAMs) using infrared reflection absorption spectroscopy (IRRAS) and density functional theory (DFT). Xe, Kr, CH2Cl2, CD2Cl2, and CDCl3 were used experimentally to perturb the CH2 and CH3 stretches arising from the tail region of the SAM films and changes in position and intensity were monitored in the infrared. Using DFT methods, noble gases and CH2Cl2 were added to models of the SAM monolayers, and energies and vibrational spectra were calculated. It was observed that perturbing species affected the CH3 symmetric and asymmetric stretches on hexadecanethiol SAMs (an "even" SAM with a 16-carbon backbone) while on pentadecanethiol SAMs (an "odd" SAM with a 15-carbon backbone) both CH2 and CH3 symmetric and asymmetric stretches were affected. Films formed with shorter chain-length species, hexanethiol (even) and pentanethiol (odd), had less consistent results, likely due to more disorder in the alkanethiol chains from weaker van der Waals interactions. Adsorption energies for different perturbing species on the monolayers were higher for the hexanethiol than the pentanethiol. The vibrational spectrum of pentanethiol monolayers with adsorbed species mainly showed shifts to higher frequencies for CH2 and CH3 stretches; for hexanethiol, shifts to lower frequencies for CH2 stretches and higher frequencies for CH3 stretches were observed. Thus, the odd and even alkanethiol SAMs were affected differently by the perturbing species as observed both experimentally and computationally. [ABSTRACT FROM AUTHOR]

Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3 catalysts to modify the support to enable control over CO2 adsorption and CO2 hydrogenation activity. Significant differences in catalytic activity toward CO2 hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3 with PAs, suggesting that the reaction was mediated by CO2 adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2 as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2 adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2 adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2 hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3 support by the PAs. [ABSTRACT FROM AUTHOR]

Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3 catalysts to modify the support to enable control over CO2 adsorption and CO2 hydrogenation activity. Significant differences in catalytic activity toward CO2 hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3 with PAs, suggesting that the reaction was mediated by CO2 adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2 as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2 adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2 adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2 hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3 support by the PAs. [ABSTRACT FROM AUTHOR]

Carbazole‐based self‐assembled molecules (SAMs) are widely applied in inverted perovskite solar cells (iPSCs) due to their unique molecular properties. However, the symmetrical structure of the carbazole‐based SAMs makes it difficult to finely regulate their performance, which impedes the further enhancement of the efficiency and stability of iPSCs. This work demonstrates that by constructing an asymmetric carbazole core, 9H‐thieno[2′,3′ : 4,5]thieno[3,2‐b]indole) (TTID), the key properties of SAM molecules can be effectively regulated. It has been confirmed that the hybrid thieno[2,3‐b]thiophene unit of this asymmetric core governs the energy level, the surface wettability, and the defect passivation capability of the SAMs, while the substituent of core has a greater impact on the molecular dipole and device stability. The synergistic effects from thieno[2,3‐b]thiophene and fluorine lead to the KF‐derived iPSC demonstrating a certified power conversion efficiency (PCE) of 25.17 % and excellent operational stability. This hybrid design concept offers a promising approach for the further structural modification of SAMs in iPSCs. [ABSTRACT FROM AUTHOR]

In this study, a new electrochemical sensor based on self-assembled monolayers of Cys-GA-Gln-Cu2+ modified gold electrode was fabricated. The electrocatalytic activity of adsorbed copper ions was utilized to determine the quantitative concentration of curcumin. Techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with an external redox probe were used to investigate the layer-bylayer modification on the gold electrode surface. This electrode showed selective and reproducible adsorption for Cu2+In the absence of curcumin, the DPV redox peak for Cu2+ was observed at about 276 mV with an anodic current of 1.36 μA vs. Ag/AgCl for 5.0x10-4M of copper. In the presence of curcumin, an anodic peak was observed at 292 mV vs. Ag/AgCl with 3.86 μA for 5x10-4 M of Cu2+. The results demonstrated that the electrocatalytic properties of copper in the presence of curcumin could be used as a precise sensor for the determination of trace concentrations of curcumin in human blood serum. The differential pulse voltammetric response of the modified SAM electrode was linear against curcumin concentration in the range of 1 x 10-6 to 1 x 10-10 M with an R²=0.9982 at pH= 5. The relative standard deviation (RSD) determined by DPV was 4.1%. Advantages of the sensor include good sensitivity, selectivity, simple recovery, and an inexpensive preparation method. The detection limit could be estimated 1.31x10-11 M according to the IUPAC recommendation (3σ). [ABSTRACT FROM AUTHOR]

Self-assembled monolayers were first described in the 1980s and have now become ubiquitous in many interfacial technologies. In this account, we discuss different self-assembled monolayer systems, outlining their positives and negatives. We then overview other researchers' work and our own group's journey in using self-assembled monolayers to develop new concepts in sensing and addressing general challenges faced by many types of sensors. Finally, we reflect on some of the challenges monolayer chemistry needs to address to facilitate further use of this powerful surface chemistry in commercial devices. Self-assembled monolayers (SAMs) allow surfaces to be modified with molecular-level control to give surface-specific functionality. SAMs have provided fundamental insight into surface phenomena and found utility in a range of applications. This account outlines a variety of different SAM systems and their application in sensing. (Image credit: Essam M. Dief.) This article belongs to the 10th Anniversary Collection of RACI and AAS Award papers. [ABSTRACT FROM AUTHOR]

Abstract The rational design of surfaces at the molecular level is essential toward realizing many engineering applications. However, molecular‐scale defects affect processes such as triboelectrification, scaling, and condensation. These defects are often detectable via contact angle hysteresis (CAH) measurements. Liquid‐like surfaces exhibit extremely low CAH (≤5°) and rely on the use of highly flexible molecular species such as long‐chain alkyls or siloxanes. Their low glass transition temperatures lead to the so‐termed self‐smoothing behavior, reducing sensitivity to defects formed during fabrication. However, utilizing rigid molecular species such as perfluoroalkyl chains often results in higher hysteresis (10° to 60°) as defects are not self‐smoothed after fabrication. Consequently, state‐of‐the‐art perfluoroalkylated surfaces often show sub‐optimal interfacial properties. Here, a customizable chemical vapor deposition process creates molecularly‐thick, low‐defect surfaces from trichloro(1H,1H,2H,2H‐perfluorooctyl)silane. By implementing moisture‐exposure controls, highly homogenous surfaces with root‐mean‐square roughness below 1 nm are fabricated. CAH is achieved down to ≈4° (average: 6°), surpassing the state‐of‐the‐art by ≈5°. Reduction of CAH (26° to 6°) results in condensation suppression, decreasing surface droplet density by one order and surface droplet coverage by 40%. This work guides the synthesis of high‐quality surfaces from tri‐functional perfluoroalkylsilanes with liquid‐like properties despite their molecular rigidity.

Abstract Herein, additive manufacturing, which is extremely promising in different sectors, has been adopted in the electrical energy storage field to fabricate efficient materials for supercapacitor applications. In particular, Al2O3-, steel-, and Cu-based microparticles have been used for the realization of 3D self-assembling materials covered with reduced graphene oxide to be processed through additive manufacturing. Functionalization of the particles with amino groups and a subsequent "self-assembly" step with graphene oxide, which was contextually partially reduced to rGO, was carried out. To further improve the electrical conductivity and AM processability, the composites were coated with a polyaniline-dodecylbenzene sulfonic acid complex and further blended with PLA. Afterward, they were extruded in the form of filaments, printed through the fused deposition modeling technique, and assembled into symmetrical solid-state devices. Electrochemical tests showed a maximum mass capacitance of 163 F/g, a maximum energy density of 15 Wh/Kg at 10 A/g, as well as good durability (85% capacitance retention within 5000 cycles) proving the effectiveness of the preparation and the efficiency of the as-manufactured composites.

Surface or interface engineering is one of the most effective strategies to improve the device performance and stability of perovskite solar cells (PSCs), owing to the fact that the defects are mainly located at the surface. Organosilanes are among the most promising surface modifiers due to their unique cross‐linking ability, which makes a robust layer to further protect the underneath perovskites. However, the influence of tail functional groups of organosilanes on the device performance and stability has never been systematically investigated. Herein, a series of organosilanes with different chain lengths, fluorination, and different interactions toward perovskite are applied to modify the perovskite. Tail functional groups that show passivation ability toward perovskite are demonstrated to effectively reduce trap densities and thus improve the power conversion efficiencies (PCEs), while the fluorinated functional groups are beneficial for high stability. Finally, PSCs based on 3,3,3‐trifluoropropyltrimethoxysilane (FPTMS) modification showed a high PCE of 23.0% with the best operational stability. The encapsulated device maintained 85% of the initial PCE after 1725 h under continuous 1 sun equivalent illumination in air. The work may provide important insights into designing modifiers for high‐performance PSCs with high stability. [ABSTRACT FROM AUTHOR]

Three functionalized thienopyrazines (TPs), TP‐MN (1), TP‐CA (2), and TPT‐MN (3) were designed and synthesized as self‐assembled monolayers (SAMs) deposited on the NiOx film for tin‐perovskite solar cells (TPSCs). Thermal, optical, electrochemical, morphological, crystallinity, hole mobility, and charge recombination properties, as well as DFT‐derived energy levels with electrostatic surface potential mapping of these SAMs, have been thoroughly investigated and discussed. The structure of the TP‐MN (1) single crystal was successfully grown and analyzed to support the uniform SAM produced on the ITO/NiOx substrate. When we used NiOx as HTM in TPSC, the device showed poor performance. To improve the efficiency of TPSC, we utilized a combination of new organic SAMs with NiOx as HTM, the TPSC device exhibited the highest PCE of 7.7 % for TP‐MN (1). Hence, the designed NiOx/TP‐MN (1) acts as a new model system for the development of efficient SAM‐based TPSC. To the best of our knowledge, the combination of organic SAMs with anchoring CN/CN or CN/COOH groups and NiOx as HTM for TPSC has never been reported elsewhere. The TPSC device based on the NiOx/TP‐MN bilayer exhibits great enduring stability for performance, retaining ~80 % of its original value for shelf storage over 4000 h. [ABSTRACT FROM AUTHOR]

Field-effect transistors (FETs) based on two-dimensional molybdenum disulfide (2D-MoS2) have great potential in electronic and optoelectronic applications, but the performances of these devices still face challenges such as scattering at the contact interface, which results in reduced mobility. In this work, we fabricated high-performance MoS2-FETs by inserting self-assembling monolayers (SAMs) between MoS2 and a SiO2 dielectric layer. The interface properties of MoS2/SiO2 were studied after the inductions of three different SAM structures including (perfluorophenyl)methyl phosphonic acid (PFPA), (4-aminobutyl) phosphonic acid (ABPA), and octadecylphosphonic acid (ODPA). The SiO2/ABPA/MoS2-FET exhibited significantly improved performances with the highest mobility of 528.7 cm2 V−1 s−1, which is 7.5 times that of SiO2/MoS2-FET, and an on/off ratio of ~106. Additionally, we investigated the effects of SAM molecular dipole vectors on device performances using density functional theory (DFT). Moreover, the first-principle calculations showed that ABPA SAMs reduced the frequencies of acoustic and optical phonons in the SiO2 dielectric layer, thereby suppressing the phonon scattering to the MoS2 channel and further improving the device's performance. This work provided a strategy for high-performance MoS2-FET fabrication by improving interface properties. [ABSTRACT FROM AUTHOR]

Self-assembled monolayers (SAMs) on an SiO2 surface were investigated using periodic DFT calculations. The stability of SAMs on SiO2 surfaces was influenced by modifications in head groups, coverage, and space group length. Three molecules were considered as trial molecular chains: methyltrichlorosilane (CH3SiCl3), acetyl chloride (CH3COCl), and methylphosphonic acid (CH3PO(OH)2), with CH3SiCl3 being chosen because of the stable chemisorption complex of its -SiCl3 functional group to the surface and the nonpolar hydrophobic nature of CH3. The stability of each SAM was evaluated using the molecular chain length in terms of CH3(CH2)nSiCl3, where n = 0-9, and three distinct coverages (1/4, 1/2, and 1 ML). Our findings revealed that coverage and molecular chain length had a major influence on SAM stability, with van der Waals interactions outweighing steric interactions during molecular chain lengthening. [ABSTRACT FROM AUTHOR]

The development of high‐performance organic solar cells (OSCs) with high operational stability is essential to accelerate their commercialization. Unfortunately, our understanding of the origin of instabilities in state‐of‐the‐art OSCs based on bulk heterojunction (BHJ) featuring non‐fullerene acceptors (NFAs) remains limited. Herein, we developed NFA‐based OSCs using different charge extraction interlayer materials and studied their storage, thermal, and operational stabilities. Despite the high power conversion efficiency (PCE) of the OSCs (17.54%), we found that cells featuring self‐assembled monolayers (SAMs) as hole‐extraction interlayers exhibited poor stability. The time required for these OSCs to reach 80% of their initial performance (T80) was only 6 h under continuous thermal stress at 85 °C in a nitrogen atmosphere and 1 h under maximum power point tracking (MPPT) in a vacuum. Inserting MoOx between ITO and SAM enhanced the T80 to 50 and ~15 h after the thermal and operational stability tests, respectively, while maintaining a PCE of 16.9%. Replacing the organic PDINN electron transport layer with ZnO NPs further enhances the cells' thermal and operational stability, boosting the T80 to 1000 and 170 h, respectively. Our work reveals the synergistic roles of charge‐selective interlayers and device architecture in developing efficient and stable OSCs. [ABSTRACT FROM AUTHOR]

Inverted positive‐intrinsic‐negative (p‐i‐n) perovskite solar cells (IPSCs) have attracted widespread attention due to their low fabrication temperature, good stability in ambient air, and the potential for use in flexible and tandem devices. In recent years, self‐assembled monolayers (SAMs) have been investigated as a promising hole‐selective contact for IPSCs, leading to an impressive record efficiency of about 26%, which is comparable to that of the regular n‐i‐p counterparts. This review focuses on the progress of SAM‐based IPSCs from the perspective of energy level matching, defect passivation, interface carrier extraction, and SAMs' stability improvement, as well as the advances in up‐scalable fabrication of SAMs and perovskite layers for efficient solar modules and tandem devices. A cost analysis of the SAMs and other commonly used hole‐selective materials is conducted to evaluate their cost‐effectiveness for photovoltaic applications. Finally, the future challenges are pointed out and the perspectives on how to up‐scale SAM‐based IPSCs and improve their long‐term operational stability are provided. [ABSTRACT FROM AUTHOR]

Stainless steel (SST) is an important material for a variety of applications including construction, food, and medical. Highly hydrophobic wetting properties enhance the surface properties of SST to support processes such as self‐cleaning. However, applications also require long‐term stability of such properties against chemical and mechanical influences from the environment or technical processes. Therefore, the reduction of highly hydrophobicity of chemically modified, laser‐textured SST surfaces is investigated in relation to abrasive wear using hierarchical structures, micro‐/nanotextured surface, and support structures that shield the highly hydrophobic pattern. Surface textures comprising ridges, grooves (size: 50–500 μm; depth: up to 100 μm), and a nanostructured grooves bottom are machined by infrared ultrashort pulse laser ablation into SST and are subsequently chemically modified by a self‐assembled monolayer of a fluorinated, phosphonic acid‐modified alkane. Abrasive wear tests of these surfaces show decreasing water contact angles with increasing wear of the modified surface of the support structures. However, there is good stability of the highly hydrophobic properties due to the protection of modified areas at the groove bottom. The proposed wetting model for such designed functionalized laser textures shows possibilities for further optimization of such robust highly hydrophobic surfaces and adaptation to specific applications. [ABSTRACT FROM AUTHOR]

Self-assembled monolayers (SAMs) have been widely employed as hole transport layers (HTLs) to construct efficient and stable organic–inorganic hybrid perovskite solar cells (PSCs). However, the related application of SAMs in inverted inorganic PSCs is still extremely limited. Herein, [2-(9H-carbazol-9-yl) ethyl] phosphonic acid (2PACz) is successfully developed as a nanoscale HTL to fabricate high-performance inorganic CsPbI3 PSCs. Compared with the conventional poly triphenyl-amine (PTAA), 2PACz SAM can tightly anchor on the fluorine-doped tin oxide (FTO) surface via chemical coordination, rendering a more favorable interface contact and matched energy level alignment with the perovskite. Besides, the perovskite film quality and interfacial charge extraction are greatly ameliorated, leading to suppressed charge recombination and voltage loss. As a result, the inverted CsPbI3 PSC with 2PACz HTL exhibits a champion power conversion efficiency (PCE) of 18.89% in contrast to the PTAA device with a lower PCE of 17.07%. Moreover, both the unencapsulated 2PACz-based perovskite film and device stability present significant improvement. This study provides insights into the underexplored application of SAMs in inorganic PSCs, which will accelerate the advancement of perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

Four different carbazole‐based self‐assembled molecules (SAMs) with different terminal groups have been designed and synthesized as hole‐selective contacts for inverted perovskite solar cells to investigate their interfacial interactions and, consequently, the performance of the devices. Using the carbazole core as a reference, the effect of the thiophen‐2‐yl phenyl, or the hydroxymethyl phenyl attached to the core through a phenyl moiety, with that of the thiophene directly linked to the carbazole is compared. These new SAMs have been successfully synthesized using cost‐effective starting materials and a straightforward synthetic method, eliminating the need for expensive and complex purification processes. Subsequently, they have been applied as efficient hole‐selective contact in inverted perovskite solar cells, leading to an outstanding power conversion efficiency of 19.67% in the case of SAM5, containing a carbazole‐core substituted with double 2‐phenylthiophene side arms as functional group. The detailed characterization of the interface and the charge kinetics has allowed to determine the effect of each substituent. [ABSTRACT FROM AUTHOR]

Porous aromatic frameworks (PAFs) show promising potential in anionic conduction due to their high stability and customizable functionality. However, the insolubility of most PAFs presents a significant challenge in their processing into membranes and subsequent applications. In this study, continuous PAF membranes with adjustable thickness were successfully created using liquid‐solid interfacial polymerization. The rigid backbone and the stable C−C coupling endow PAF membrane with superior chemical and dimensional stabilities over most conventional polymer membranes. Different quaternary ammonium functionalities were anchored to the backbone through flexible alkyl chains with tunable length. The optimal PAF membrane exhibited an OH− conductivity of 356.6 mS ⋅ cm−1 at 80 °C and 98 % relative humidity. Additionally, the PAF membrane exhibited outstanding alkaline stability, retaining 95 % of its OH− conductivity after 1000 hours in 1 M NaOH. To the best of our knowledge, this is the first application of PAF materials in anion exchange membranes, achieving the highest OH− conductivity and exceptional chemical/dimensional stability. This work provides the possibility for the potential of PAF materials in anionic conductive membranes. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have attracted much attention due to their low cost, high efficiency, and solution processability. With the development of various materials in perovskite solar cells, self-assembled monolayers (SAMs) have rapidly become an important factor in improving power conversion efficiency (PCE) due to their unique physical and chemical properties and better energy level matching. In this topical review, we introduced important categories of self-assembled molecules, energy level modulation strategies, and various characteristics of self-assembled molecules. In addition, we focused on reviewing the application of self-assembled molecules in solar cells, and explained the changes that self-assembled molecules bring to PSCs by introducing the mechanism and effect of self-assembled molecules. Finally, we also elaborated on the challenges currently faced by self-assembled molecules and provided prospects for their applications in other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Self-assembled monolayers (SAMs) represent an important tool in context of nanofabrication and molecular engineering of surfaces and interfaces. The properties of functional SAMs depend not only on the character of the tail groups at the SAM-ambient interface, but are also largely defined by their structure. In its turn, the latter parameter results from a complex interplay of the structural forces and a variety of other factors, including so called odd-even effects, viz. dependence of the SAM structure and properties on the parity of the number (odd or even) of individual building blocks in the backbone of the SAM constituents. The most impressive manifestation of the odd-even effects is the structure of aryl-substituted alkanethiolate SAMs on Au(111) and Ag(111), in which, in spite of the fact that the intermolecular interaction is mostly determined by the aryl part of the monolayers, one observes a pronounced dependence of molecular inclination and, consequently, the packing density of the SAM-forming molecules on the parity of number of methylene units in the alkyl linker. Here we review the properties of the above systems as well as address fundamental reasons behind the odd-even effects, including the existence of a so-called bending potential, which is frequently disregarded in analysis of the structure-building forces. The generality of the odd-even effects in SAMs is additionally supported by the recent data for SAMs on GaAs, scanning tunneling microscopy data for SAMs on Ag(111), and the data for the monolayers with selenolate and carboxyl anchoring groups on Au(111) and Ag(111). The implications of these effects in terms of the control over the packing density and orientation of the tail groups at the SAM-ambient interface, structural perfection, polymorphism, temperature-driven phase transitions, and SAM stability toward such factors as ionizing radiation, exchange reaction, and electrochemical desorption are discussed. These implications place the odd-even effects as an important tool for the design of functional SAMs in context of specific applications. [ABSTRACT FROM AUTHOR]

The hole‐transporting material (HTM), poly (3,4‐ethylene dioxythiophene) poly(styrene sulfonate) (PEDOT : PSS), is the most widely used material in the realization of high‐efficiency organic solar cells (OSCs). However, the stability of PEDOT : PSS‐based OSCs is quite poor, arising from its strong acidity and hygroscopicity. In addition, PEDOT : PSS has an absorption in the infrared region and high highest occupied molecular orbital (HOMO) energy level, thus limiting the enhancement of short‐circuit current density (Jsc) and open‐circuit voltage (Voc), respectively. Herein, two asymmetric self‐assembled molecules (SAMs), namely BrCz and BrBACz, were designed and synthesized as HTM in binary OSCs based on the well‐known system of PM6 : Y6, PM6 : eC9, PM6 : L8‐BO, and D18 : eC9. Compared with BrCz, BrBACz shows larger dipole moment, deeper work function and lower surface energy. Moreover, BrBACz not only enhances photon harvesting in the active layer, but also minimizes voltage losses as well as improves interface charge extraction/ transport. Consequently, the PM6 : eC9‐based binary OSC using BrBACz as HTM exhibits a champion efficiency of 19.70 % with a remarkable Jsc of 29.20 mA cm−2 and a Voc of 0.856 V, which is a record efficiency for binary OSCs so far. In addition, the unencapsulated device maintains 95.0 % of its original efficiency after 1,000 hours of storage at air ambient, indicating excellent long‐term stability. [ABSTRACT FROM AUTHOR]

Stabilizing the Zn anode under high utilization rates is highly applauded yet very challenging in aqueous Zn batteries. Here, we rationally design a zincophilic short-chain aromatic molecule, 4-mercaptopyridine (4Mpy), to construct self-assembled monolayers (SAMs) on a copper substrate to achieve highly utilized Zn anodes. We reveal that 4Mpy could be firmly bound on the Cu substrate via Cu-S bond to form compact and uniform SAMs, which could effectively isolate the water on the electrode surface and thus eliminate the water-related side reactions. In addition, the short-chain aromatic ring structure of 4Mpy could not only ensure the ordered arrangement of zincophilic pyridine N but also facilitate charge transfer, thus enabling uniform and rapid Zn deposition. Consequently, the Zn/4Mpy/Cu electrode not only enables the symmetric cell to stably cycle for over 180 h at 10 mA cm-2 under a high depth-of-discharge of 90%, but also allows the MnO2-paired pouch cell to survive for 100 cycles under a high Zn utilization rate of 78.8%. An anode-free 4Mpy/Cu||graphite cell also operates for 150 cycles without obvious capacity fading at 0.1 A g-1. This control of interfacial chemistry via SAMs to achieve high utilization rates of metal anodes provides a new paradigm for developing high-energy metal-based batteries. [ABSTRACT FROM AUTHOR]

A miniature L-glutamate (L-Glu) biosensor is described based on Prussian blue (PB) modification with improved stability by using self-assembled monolayers (SAMs) technology and polydopamine (PDA). A gold microelectrode (AuME) was immersed in NH2(CH2)6SH-ethanol solution, forming well-defined SAMs via thiol-gold bonding chemistry which increased the number of deposited Prussian blue nanoparticles (PBNPs) and confined them tightly on the AuME surface. Then, dopamine solution was dropped onto the PBNPs surface and self-polymerized into PDA to protect the PB structure from destruction. The PDA/PB/SAMs/AuME showed improved stability through CV measurements in comparison with PB/AuME, PB/SAMs/AuME, and PDA/PB/AuME. The constructed biosensor achieved a high sensitivity of 70.683 nA µM−1 cm−2 in the concentration range 1–476 µM L-Glu with a low LOD of 0.329 µM and performed well in terms of selectivity, reproducibility, and stability. In addition, the developed biosensor was successfully applied to the determination of L-Glu in tomato juice, and the results were in good agreement with that of high-performance liquid chromatography (HPLC). Due to its excellent sensitivity, improved stability, and miniature volume, the developed biosensor not only has a promising potential for application in food sample analysis but also provides a good candidate for monitoring L-Glu level in food production. [ABSTRACT FROM AUTHOR]

Abstract Self‐assembled monolayers (SAMs) employed in inverted perovskite solar cells (PSCs) have achieved groundbreaking progress in device efficiency and stability for both single‐junction and tandem configurations, owing to their distinctive and versatile ability to manipulate chemical and physical interface properties. In this regard, we present a comprehensive review of recent research advancements concerning SAMs in inverted perovskite single‐junction and tandem solar cells, where the prevailing challenges and future development prospects in the applications of SAMs are emphasized. We thoroughly examine the mechanistic roles of diverse SAMs in energy‐level regulation, interface modification, defect passivation, and charge transportation. This is achieved by understanding how interfacial molecular interactions can be finely tuned to mitigate charge recombination losses in inverted PSCs. Through this comprehensive review, we aim to provide valuable insights and references for further investigation and utilization of SAMs in inverted perovskite single‐junction and tandem solar cells.

The wide use of copper is limited by its rapid oxidation. Main oxidation mitigation approaches involve alloying or surface passivation technologies. However, surface alloying often modifies the physical properties of copper, while surface passivation is characterized by limited thermal and chemical stability. Herein, we demonstrate an electrochemical approach for surface-anchoring of an N-heterocyclic carbene (NHC) nanolayer on a copper electrode by electro-deposition of alkyne-functionalized imidazolium cations. Water reduction reaction generated a high concentration of hydroxide ions that induced deprotonation of imidazolium cations and self-assembly of NHCs on the copper electrode. In addition, alkyne group deprotonation enabled on-surface polymerization by coupling surface-anchored and solvated NHCs, which resulted in a 2 nm thick NHC-nanolayer. Copper film coated with a NHC-nanolayer demonstrated high oxidation resistance at elevated temperatures and under alkaline conditions.