Au Interface Research Articles

Improved performance of CH3NH3PbI3 based photodetector with a MoO3 interface layer

Abstract Planar CH 3 NH 3 PbI 3 perovskite based photodetectors are fabricated by a facile and low-cost one-step method. The devices show broad spectral photoresponse from the ultraviolet to whole visible region and the performance can be significantly improved by the introduction of a bipolar transporting MoO 3 interface layer between CH 3 NH 3 PbI 3 film and Au electrode. The photocurrent of the device with an optimized MoO 3 layer is about twice that of the reference device without MoO 3 layer, which results in a high ON/OFF current ratio of 5.9 × 10 3 at 5 V. Besides, slightly increased photoresponse speed is also found in the optimized device with rise time and decay time of 21.6 and 9.9 ms, respectively. The improvement can be attributed to the improved hole and electron collection efficiency and the quickly filled in or emptied trap states at the CH 3 NH 3 PbI 3 /Au interface due to the introduction of the bipolar transporting MoO 3 layer.

Characterization of opto-electrical enhancement of tandem photoelectrochemical cells by using photoconductive-AFM

Solar-to-hydrogen conversion by water splitting in photoelectrochemical cells (PECs) is a promising approach to alleviate problems associated with intermittency in solar energy supply and demand. Several interfacial resistances in photoelectrodes limit the performance of such cells, while the properties of interfaces are not easy to analyze in situ. We applied photoconductive-AFM to analyze the performance of WO3/p+n Si photoanodes, containing an ultra-thin metal interface of either Au or Pt. The Au interface consisted of Au nanoparticles with well-ordered interspacing, while Pt was present in the form of a continuous film. Photoconductive-AFM data show that upon illumination significantly larger currents are measured for the WO3/p+n Si anode equipped with the Au interface, as compared to the WO3/p+n Si anode with the Pt interface, in agreement with the better performance of the former electrode in a photoelectrochemical cell. The remarkable performance of the Au-containing electrode is proposed to be the result of favorable electron-hole recombination rates induced by the Au nanoparticles in a plasmon resonance excited state.

Facet-Specific Adsorption of Tripeptides at Aqueous Au Interfaces: Open Questions in Reconciling Experiment and Simulation.

The adsorption of three homo-tripeptides, HHH, YYY, and SSS, at the aqueous Au interface is investigated, using molecular dynamics simulations. We find that consideration of surface facet effects, relevant to experimental conditions, opens up new questions regarding interpretations of current experimental findings. Our well-tempered metadynamics simulations predict the rank ordering of the tripeptide binding affinities at aqueous Au(111) to be YYY > HHH > SSS. This ranking differs with that obtained from existing experimental data which used surface-immobilized Au nanoparticles as the target substrate. The influence of Au facet on these experimental findings is then considered, via our binding strength predictions of the relevant amino acids at aqueous Au(111) and Au(100)(1 × 1). The Au(111) interface supports an amino acid ranking of Tyr > HisA ≃ HisH > Ser, matching that of the tripeptides on Au(111), while the ranking on Au(100) is HisA > Ser ≃ Tyr ≃ HisH, with only HisA showing non-negligible binding. The substantial reduction in Tyr amino acid affinity for Au(100) vs Au(111) offers one possible explanation for the experimentally observed weaker adsorption of YYY on the nanoparticle-immobilized substrate compared with HHH. In a separate set of simulations, we predict the structures of the adsorbed tripeptides at the two aqueous Au facets, revealing facet-dependent differences in the adsorbed conformations. Our findings suggest that Au facet effects, where relevant, may influence the adsorption structures and energetics of biomolecules, highlighting the possible influence of the structural model used to interpret experimental binding data.

Evolution at the Solid Electrolyte/Gold Electrode Interface during Lithium Deposition and Stripping

Quasi-binary thiophosphate-based solid electrolytes (SEs) are attracting substantial interest for lithium batteries due to their outstanding room temperature ionic conductivities. This work describes reactions occurring at the solid electrolyte (SE)/Au interface during Li deposition and stripping for two exemplary SE materials: β-Li3PS4 (β-LPS) and Li10GeP2S12 (LGPS). We used in situ Raman spectroscopy, along with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to evaluate potential-dependent changes in the chemistry of these materials at active electrode interfaces. For β-LPS, a partially reversible conversion of PS43– to P2S64– was found along with the formation of Li2S during Li deposition and stripping. In contrast, LGPS exhibited only irreversible changes at potentials below 0.7 V vs Li+/Li. The different behaviors likely relate to differences in the structures of the two SE materials and the availability of easily bridged anion components in close proximity. The work sh...

Interfacial reactions in the Au/Sn-xZn/Cu sandwich couples

Abstract The interfacial reactions in the Au/Sn-Zn/Cu sandwich couples were investigated. The Sn-xZn/Cu couples were reflowed at 270 °C for 1 h and then clamped together over an Au foil. These Au/Sn-Zn/Cu sandwich couples were aged at 160 °C for various periods of time. The AuSn, AuSn2, and AuSn4 phases were formed at the Sn-1Zn/Au interface when the Au/Sn-1 wt% Zn/Cu sandwich couple was aged for 20 h, the Cu6Sn5 phase was also observed between Au-Sn intermetallic compounds (IMCs) and solder. This result revealed that Cu atoms rapidly diffused through the Sn-1Zn solder to form Cu-Zn IMC on the Au side. The Au-Sn IMCs, Au-Zn IMCs, and an Au-Sn-Zn ternary metastable phase were formed at the interface in the Sn-5Zn/Au and Sn-9 wt% Zn/Au couple. When Zn contents were more than 20 wt%, only the Au-Zn IMCs, AuZn, Au3Zn7, and AuZn3 phase were formed at the Sn-xZn/Au interface. On the Cu side, when the Sn-Zn/Cu couple was reflowed at 270 °C for 1 h, the result indicated that the (Cu, Zn)6Sn5, (Cu, Sn)Zn phases were found at the Sn-1 wt.% Zn/Cu interface, the Cu5Zn8 phase was found at the Sn-5Zn/Cu interface and the (Cu, Sn)5Zn8, (Cu, Sn)Zn5 phases were found at the Sn-xZn/Cu interfaces (x = 9, 20 and 40 wt%). After 1000-h aging, the CuZn and Cu6Sn5 phases were formed at the Sn-1Zn/Cu interface, and only the Cu5Zn8 phase was observed at the Sn-(5 to 40) wt% Zn/Cu interfaces. The results indicated that no Au-Cu ordered phases were observed at both Au and Cu sides, and IMC formation in the Au/(Sn-xZn)/Cu sandwich couple strongly depended on the Zn concentration effect in the Sn-xZn alloys.

Role of work function in field emission enhancement of Au island decorated vertically aligned ZnO nanotapers

In this report, we demonstrate significantly enhanced field emission properties of ZnO nanotapers achieved via a corrugated decoration of Au. Field emission experiments on these Au-decorated ZnO nanotapers showed emission current densities comparable to the best results in the literature. Au decoration of 5nm also reduced the effective turn-on field to ∼0.54V/μm, compared to the as grown ZnO nanotapers, which showed a turn-on field of ∼1.1V/μm. Tunneling atomic force microscopy measurements revealed a very uniform spatial emission profile in the 5nm Au decorated nanotapers, which is a basic requirement for any large scale application. We believe that metal induced mid-gap states formed at the ZnO–Au interface are responsible for the observed low turn-on field because such interface states are known to reduce the effective work function. A direct measurement of effective work function using Kelvin probe force microscopy indeed showed more than 1.1eV drop in the case of 5nm Au decorated ZnO nanotapers compared to the pristine nanotapers, supporting the above argument.

Enhanced plasmon-mediated photo-assisted hydrogen evolution on silicon by interfacial modification

The superior catalytic activity of Pt towards proton reduction suggests application of Pt also in device architectures where hydrogen is produced by light-generated charge carriers. Large optical absorption cross sections of Pt nanoparticles, however, turn the attention to potential substitutes for Pt such as Au with more advantageous optical properties. In order to approach a functional Si/Au photocathode for hydrogen evolution, we report here on modifications of the Si–Au interface which result in improvements of charge transfer kinetics and optical properties of the device. After current-less deposition of Au nanoparticles onto silicon, these improvements are realized by chemical oxide exchange reactions at the Si/SiO_2/Au interface, i.e., dynamic etching of SiO_2 and re-oxidation of Si in NH_4F (40%). A chemical reaction route for the reformation of the SiO_2 layer in the presence of Au and the aqueous NH_4F solution is discussed. Simultaneous to the modification of the Si/SiO_2 interface, small Au nanoparticles form larger clusters with enhanced effective scattering cross sections. Thereby, improved electronic interface properties and enhanced forward scattering of light increase the saturation photocurrent density by about 9% from 32 to 35 mA cm^(−2). Improved stability of the device in acidic electrolytes, near the thermodynamic potential for evolution of hydrogen, is furthermore discussed.

Nanoscale Wire Bonding of Individual Ag Nanowires on Au Substrate at Room Temperature

The controllable wire bonding of individual Ag nanowires onto a Au electrode was achieved at room temperature. The plastic deformation induced by pressure using nanoindentation could break the protective organic shell on the surface of the Ag nanowires and cause atomic contact to promote the diffusion and nanojoining at the Ag and Au interface. Severe slip bands were observed in the Ag nanowires after the deformation. A metallic bond was formed at the interface, with the Ag diffusing into the Au more than the Au diffused into the Ag. This nanoscale wire bonding might present opportunities for nanoscale packaging and nanodevice design.Graphical

Interfacial Structure at the Quaternary Ammonium-Based Ionic Liquids|Gold Electrode Interface Probed by Surface-Enhanced Infrared Absorption Spectroscopy: Anion Dependence of the Cationic Behavior

The interfacial structure at the quaternary ammonium-based ionic liquids(ILs)|gold(Au) electrode interface has been studied using surface-enhanced infrared absorption spectroscopy (SEIRAS). Four anions, bis(perfluoroalkanesulfonyl)amide (CnCnN–; n = 0, 1, 2, 4), have been combined with a quaternary ammonium cation, trioctylmethylammonium (N8881+), to investigate the influence of the perfluoroalkyl chain length of the anion on the behavior of the quaternary ammonium cation at the interface. In addition, to investigate the effect of the alkyl chain length of the quaternary ammonium cations on the cationic behavior, we have also combined a cation with a shorter alkyl chain, tributylmethylammonium (N4441+) with C1C1N–. Thus, we have performed SEIRAS measurements at the Au interface of five ILs: [N8881+][CnCnN–] (n = 0, 1, 2, 4) and [N4441+][C1C1N–]. The four CH stretching bands originating from the quaternary ammonium cations have been individually analyzed, enabling us to reveal the behavior of the quaternar...

Bonding Characteristics of Sn-57Bi-1Ag Low-Temperature Lead-Free Solder to Gold-Plated Copper

To fabricate a higher melting point joint by bonding at a low temperature, bonding characteristics of Au/Cu joints bonded at various bonding conditions using Sn-57Bi-1Ag solder were investigated. They were compared with those of the Cu/Cu joint. In the Au/Cu joint bonded at 170 oC for 1min, a large scallop-shaped AuSn4 layer formed in the joint interface of Au and solder. A Au-diffused layer formed in the tip of the AuSn4 layer. The Sn-Cu-Au layer including approximately 20 mol% Au formed in the joint interface of Cu and solder. With increasing the bonding time, both the eutectic microstructure with β-Sn and Bi and the Au layer disappeared. As the result, the solder area changed from the eutectic microstructure to Bi phases including AuSn4 and Ag3Sn phases in the bonding time over 30min. In contrast, the eutectic microstructure formed in the Cu/Cu joint bonded at 170 oC regardless of the bonding time. The bond strength of the Au/Cu joint was approximately one-third of that of the Cu/Cu joint. In both joints, the bond strength reduced with increasing the bonding time due to the fracture mode change.

Interfacial Au nanoparticle decoration of a disulfide modified G-wire.

The guanine-rich oligonucleotide (GRO), dGGGGTTGGGG (G4T2G4), has the capacity to form a linear supramolecular polymer known as a G-wire. Individual nucleotides of the component GROs can be functionally modified to serve as site-specific attachment points in the G-wire while not interfering with its self-assembling properties. An amine linker modification to an internal thymine base of the GRO, denoted G4TT*G4, serves as a chemically versatile attachment site. In this work, addition of an alkyl disulfide to G4TT*G4 produces the GRO G4TTdG4 enabling binding to gold nanoparticles via place exchange chemistry. G-wires assembled by combining G4T2G4 and G4TTdG4 were stably maintained in an aqueous environment. Disulfide modified G-wires (DS_G-wire) were then covered with dodecanethiol capped gold nanoparticles in an organic solvent via an interfacial place exchange reaction. Tapping Mode AFM and TEM were used to image G-wires decorated with gold nanoparticles. The specificity of the interfacial place exchange reaction was measured using a fluorometric dye displacement from the gold nanoparticles. The results show that a two component DS_G-wire with an amphipathic tether readily self-assemble as shown by PAGE and TM-AFM. The amphipathic disulfide moiety of DS_G-wires facilitates place exchange chemistry with alkylthiol protected Au nanoparticles across an aqueous-organic interface. Interfacial place exchange is an effective strategy for decorating DS_G-wires with Au nanoparticles. The use of modified G-wire self-assembly combined with a high degree of nanoparticle binding specificity presents another strategy for the use of G-wires as a rigid one-dimensional molecular scaffold with potential applications in nanoscale device construction. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.

Two-Dimensional Self-Assembly Monitored by Hydrogen Bonds for Triphenylene-Based Molecules: New Role for Azobenzenes

A hybrid disklike/rodlike molecule comprising central triphenylene core symmetrically substituted with six azobenzene moieties (C-12) has been adsorbed at the 1,2,4-trichlorobenzene/Au(111) interface, revealing the potential of azobenzene moieties for the control of two-dimensional (2D) chiral networks. The C-12, which due to its complex molecular structure possesses a relatively large number of degrees of freedom, surprisingly forms monolayers of only one kind of structure, namely a hexagonal network of large period, 3.5 nm. By combining scanning tunneling microscopy (STM) and DFT calculations, we evidence that this specific 2D-ordering is due to cooperative weak hydrogen bonds between neighboring azobenzenes and azobenzene-Au(111) interactions. The crystallographic network is hexagonal, but azobenzene-azobenzene pairing, associated with hydrogen bonding renders the network chiral with a chirality spanning all ranges, from the molecular C-12 configuration, to the configuration of the azobenzene dimers, the rosettelike azobenzene network and the C-12 network orientation on Au(111) rotated by ±8° from the main crystallographic direction Au<110>, depending on the handedness of the molecular network. This chiral 2D system thus paves the way for the formation of macroscopic 2D molecular crystals of unique handedness, if additional enantiomeric chiral dopants can be used.

Necessary Thickness of Au Capping Layers for Room Temperature Bonding of Wafers in Air Using Thin Metal Films with Au Capping Layers

Room temperature bonding of wafers using thin metal films is applicable to any mirror-polished wafers, moreover, the bonded metal films can be used for electrical/thermal conductions and optical reflections. For this study, room temperature bonding of wafers in air using 10~300 nm-thick Ag, Cu, Al films with 2~30 nm-thick thin Au capping layers was examined, and necessary thickness of Au capping layer to bond wafers in air was discussed. 2-inch diameter micro-polished quarts glass wafers were used for this study. The Ti films (1 nm thickness) were used as underlayers to enhance the adhesion strength of the deposited films on the wafer surface. After the sputter film deposition on the surfaces of two wafers, bonding was accomplished in air of a clean room (20°C, 50% moisture level, class 100). No substrate heating was conducted during deposition or the bonding processes. Bonding in air could be accomplished using 20 nm-thick Ag, Cu films with 2 nm-thick Au capping layers without any loading pressure: once the nucleation of recrystallization at Au–Au interface of capping layers was formed, the recrystallization was propagated immediately, and the bonding was completed over the entire bonded area. 2 nm-thick Au capping layer was effective to avoid oxidation of the surfaces of these metal films in air and to nucleate the recrystallization between the connected films in the bonding process. Actually the surface energy at the bonded interface, evaluated using the blade method, was much higher than the surface energy of Au films. Necessary thickness of Au capping layer for 20 nm-thick Al films was 6 nm or more, which is 3 times thicker than those for Ag and Cu films. It is reasonable to infer that the small surface energy of Al films caused island-like initial film-growth of Au films deposited on Al films, resulting in the increase of Au capping layer thickness. Actually AMF images supported this consideration. Au capping layer thickness necessary for bonding increased as the thickness of metal films increased. For instance, 20 nm-thick Au capping layer was necessary for bonding using 300 nm-thick Al films. Moreover, loading pressure was necessary for bonding using thick metal films. These were mainly caused by an increase of the surface roughness of the metal films. Necessary thickness of Au capping layer depended on materials of metal films, however, was 1/10 or less of the thicknesses of the metal films in the present thickness range.

Potential-Dependent Structure of [BMIM][FSA]/Au Interface Studied By Surface Enhanced Infrared Absorption Spectroscopy

Room temperature ionic liquids (RTILs) are promising electrolyte materials for Li ion batteries and other electrochemical devices due to high ionic conductivity and wide electrochemical windows. It has been reported that the cathodic decomposition potential of the FSA-based RTIL is much lower than that of TFSA-based RTIL when Li salt is added, despite the similar chemical structures of FSA and TFSA anions. A mechanism for stabilization of the FSA-based RTIL on the electrode involving an interfacial structure of the RTIL has been proposed.1 The interfacial structure itself, however, has not been well elucidate yet. Surface-enhanced infrared absorption spectroscopy (SEIRAS) that can selectively probe solid/liquid interfaces is suited for direct observation of the structure of RTIL/metal electrode interface.2 In the present work, we investigated the potential-dependent structure of [BMIM][FSA] with and without Li ion on an Au electrode by using SEIRAS. For pure [BMIM][FSA], Potential-dependent SEIRA spectra indicated that at negative potentials, BMIM cations exist in the first ionic layer on the electrode and reorients depending on the potential, as previously reported for [BMIM][TFSA].2 For [BMIM][FSA] with 10 % Li salt, SEIRAS spectra suggested that BMIM cations moved further away from the electrode at negative potentials where Li UPD did not occur although electrode is negatively charged. FSA anions also did not approach to the surface. A possible interpretation of such behavior is that decomposition products of [BMIM][FSA] or Li+ ion on the electrode inhibit cations from approaching to the electrode at negative potentials, which can be the origin of the stabilization of FSA-base RTIL. Details will be shown in the presentation. Reference: 1M. Yamagata et al., Electrochim. Acta 110, 181 (2013). 2 K. Motobayashi et al., J. Phys. Chem. Lett. 4, 3110 (2013).

Bifunctional Interface of Au and Cu for Improved CO2 Electroreduction.

Gold is known currently as the most active single-element electrocatalyst for CO2 electroreduction reaction to CO. In this work, we combine Au with a second metal element, Cu, to reduce the amount of precious metal content by increasing the surface-to-mass ratio and to achieve comparable activity to Au-based catalysts. In particular, we demonstrate that the introduction of a Au-Cu bifunctional "interface" is more beneficial than a simple and conventional homogeneous alloying of Au and Cu in stabilizing the key intermediate species, *COOH. The main advantages of the proposed metal-metal bifunctional interfacial catalyst over the bimetallic alloys include that (1) utilization of active materials is improved, and (2) intrinsic properties of metals are less affected in bifunctional catalysts than in alloys, which can then facilitate a rational bifunctional design. These results demonstrate for the first time the importance of metal-metal interfaces and morphology, rather than the simple mixing of the two metals homogeneously, for enhanced catalytic synergies.

The Electrochemical Interface of Au(111) and Au(100) in HMIm-FAP Ionic Liquid

The Electrochemical Interface of Au(111) and Au(100) in HMIm-FAP Ionic Liquid

Performance improvement of ZnO/P3HT hybrid UV photo-detector by interfacial Au nanolayer

In this study, a hybrid ultraviolet (UV) photo detector comprising of hydrothermally grown highly oriented Zinc Oxide nanorod arrays (ZnO NRAs) and Poly(3-hexylthiophene-2,5-diyl) (P3HT) as an active layer was fabricated and characterized. These hybrid photo detectors demonstrated a high rectification ratio (∼117) and responsivity of 10.7A/W at −2V under incident light of wavelength 325nm. Further to investigate the effect of surface plasmon property of metal nanoparticles on the performance of hybrid UV photo detectors, ZnO NRAs were capped with dc sputtered gold (Au) metal nanolayer (∼5nm) at the ZnO-P3HT interface, prior to coating P3HT layer on top of it. It was found out that upon Au coating the absorption of the ZnO was enhanced partly in the ultraviolet and visible region. In consequence the rectification ratio and responsivity of the hybrid photo detector was enhanced drastically from 117 to 1167 and 10.7 to 17.7A/W respectively. Interestingly the reduction in dark current was observed on Au coating and it was revealed that Au nanoparticles play a key role in enhancing the performance of the hybrid photo detectors.

Synchronization of charge carrier separation by tailoring the interface of Si–Au–TiO2 heterostructures via click chemistry for PEC water splitting

Electrochemical potential gradients that are established due to appropriate band edge alignment in heterostructures can synchronize the movement of electron and hole in opposite direction. Such synchronization is critical for efficient photoelectrochemical devices and can be achieved by tailoring the interface of heterostructures. To this end, we fabricate a tailored interface of Si–Au–TiO2 heterostructure over stainless steel ((Si–Au–TiO2)/SS) for effective charge carrier separation. The fabricated electrode possesses the following tailored interfaces to enhance the charge-carrier separation/transport: 1) gold nanoparticles form interface (sandwiched) with Si as well as TiO2; 2) Si, Au, and TiO2 form the interface with SS, 3) Si–TiO2, and Si–Au interface facilitates the quenching of h+ generated in Si (via electron transfer from TiO2 and Au to Si) which facilitates electron transport to counter electrode for hydrogen generation, and 4) TiO2 forms the interface with the electrolyte solution to facilitate hole transport. Photoelectrochemical (PEC) measurements of (Si–Au–TiO2)/SS heterostructure exhibits higher performance compared to other heterostructures ((Au–Si)/SS, (Au–TiO2)/SS, (Si–TiO2)/SS, TiO2/Au/Si/SS, and Si/Au/TiO2/SS), substantiating the importance of synchronized charge transport in PEC systems. Further, electrochemical impedance spectroscopy (EIS) studies also support the synchronized charge transport in the tailored heterostructure ((Si–Au–TiO2)/SS) compared to control samples. The calculated applied bias to photo-conversion efficiency (ABPE) of ~0.4%@~0.9V applied bias, intrinsic solar to chemical conversion efficiency (ISTC) of ~0.085 (or 8.5%) @1.66V vs. RHE and electrical and solar power-to-hydrogen (ESPH) conversion efficiency of ~3.3%@~1.0V applied bias.

In situ STM imaging of polyethylene glycol adsorbed on an Au(111) electrode in pH 3

In situ scanning tunneling microscopy (STM) is used to examine the electrified interface of Au(111) immersed in a pH3 sulfate medium containing polyethylene glycol (PEG) with an average molecular weight of 6000. The cyclic voltammograms thus obtained show two sharp peaks at −0.35 and −0.38V (vs. reversible hydrogen electrode), which correlates with the STM observation of a highly ordered (2×2√3)rect structure and the adsorption of PEGs. X-ray photoelectron spectroscopy is used to examine the film formed at −0.4V, revealing prominent C–C and C–O–C structures, thereby supporting the view of adsorption and reduction PEGs on the Au(111) electrode. STM imaging at the initial stage of PEG's adsorption reveals winding linear segments 0.6nm wide and 20–40nm long, implying helical conformations of PEGs. The PEG film dissolves and yields a high density of nanoclusters, as the potential is switched stepwise from −0.4 to 0.9V.

Improving the mechanical performance of Sn57.6Bi0.4Ag solder joints on Au/Ni/Cu pads during aging and electromigration through the addition of tungsten (W) nanoparticle reinforcement

Sn57.6Bi0.4Ag solder has been reinforced successfully through the addition of tungsten (W) nanoparticles at a concentration of 0.5wt%. With the addition of W nanoparticles, the solder matrix lamellar interphase spacing was reduced by 31.0%. Due to the dispersion of W nanoparticles and the consequently refined microstructure, the mechanical properties of the solder alloy were enhanced, as indicated by a 6.2% improvement in the microhardness. During the reflow of solder on Au/Ni/Cu pads, the entire Au layer dissolved into the molten solder rapidly and a large number of (Au,Ni)(Sn,Bi)4 particles were formed. The fracture path of the as-reflowed joint was within the solder region, showing ductile characteristic, and the shear strength was reinforced by 8.2%, due to the enhanced mechanical properties of the solder. During the subsequent aging process, the Au migrated back towards the interface and a thick layer of interfacial (Au,Ni)(Sn,Bi)4 IMC was formed, leading to the shift of the fracture path to the interfacial IMC region, the transformation to brittle fracture and the deterioration of the strength of the joint, due to Au embrittlement. By adding W nanoparticles, the migration of Au was mitigated and the thickness of the (Au,Ni)(Sn,Bi)4 layer was reduced significantly, which reduced the Au embrittlement-induced deterioration of the strength of the joint. During electromigration, the segregation of the Bi-rich and Sn-rich phases and the accumulation of the (Au,Ni)(Sn,Bi)4 layer at cathode interface were mitigated by the addition of W nanoparticles, which improved the electromigration resistance.