The dynamic stability of InPb/Au solder joint volumes under thermal aging has been investigated, exploring the interplay of atmospheric and vacuum conditions. Samples were aged at 25 degrees C, 85 degrees C, and 125 degrees C under atmospheric pressure (103 mbar) and at 125 degrees C in high vacuum (HV) (10-6 mbar). Using advanced opto-digital microscopy (ODM), high-resolution X-ray microscopy (XRM), and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), we uncovered significant morphological transformations and pronounced volume shrinkage. These changes were associated with the growth of Au x In y intermetallic compounds together with Pb- and In-rich phases, forming characteristic dark rings at the solder/Au interface. The activation energy (E a) governing the shrinkage process was precisely determined to lie within 0.38-0.41 eV, consistent with diffusion-controlled migration of In and Pb into Au-rich IMCs, while acceleration factors (AFs) were quantified, enabling long-term behavior prediction. In comparison, SnPb/PtAu and SAC305/ENIG solder joints exhibited negligible volume change and slower IMC growth, highlighting the unique susceptibility of InPb/Au to volumetric variation. These findings reveal the primary influence of temperature and pressure on solder alloy integrity, providing practical insights for reliability assessment in space, aerospace, and other high-reliability electronic applications, where lead is still allowed.

The basic concepts concerning formation and operation of a junction between a semiconductor and a solution are presented in this entry. The behavior of semiconductor electrodes in the dark and under illumination, different from that of metallic electrodes, is explained with reference to the peculiar properties of semiconductors such as very low concentration of mobile electrons; presence of a gap of forbidden energies for electronic states; control by electrode potential, under appropriate conditions, of the surface concentration of carriers; and the ability of illumination to change drastically the population of minority carriers. The dependence of photoeffects on material properties and light intensity is discussed, considering also the role and effects of surface states. The relevance of interface energetics for the performances and stability of a photoelectrode in contact with different redox couples is pointed out. Some semiconducting materials like oxides and calchogenides of transition metals, possess the ability of intercalating guest charged species (either in the dark or under illumination). Such a possibility is analyzed for consideration of their employment as electrodes of secondary battery cells. The analysis takes into account the various components of the free energy which determine the cell voltage in case of a lithium-ion battery. Moreover, considerations on the electronic and crystal structures are exposed to define the relevant requirements intercalation semiconductors should satisfy in the context of the technology of lithium-ion battery. Some oxides of transition metals manifest also the capability of transporting the electrical current simultaneously via electronic and ionic charge carriers. Such a characteristic of mixed conduction renders possible the practical utilization of some semiconducting oxides either as electrodes or solid-state electrolytes of solid oxide fuel cells (SOFCs). Some significative examples of semiconducting materials for SOFCs are reported underlining with particular emphasis their ability of modulating the conduction properties or switching the type of electrical conduction under the operative conditions of a fuel cell in dependence of the nature of interfaces the semiconductors create in a SOFC. Finally, the impact the advancements in nanotechnologies and nanoparticles synthesis has had in the development of semiconducting materials for photoelectrochemical cells is outlined in the particular case of the quantum dots that have been employed as sensitizers in dye-sensitized solar cells. In this entry organic semiconductors have not been included.

This study reports the self-assembly of graphene, obtained by anodic polarization of graphite in an ethanol-water-NaOH electrolyte, into fullerenes and hollow spherical graphene particles. MALDI mass spectrometry and UV-Vis spectroscopy confirmed that smaller fullerenes (C55, C60) and larger species with AMU up to 1951 Da (equivalent to C160) emerged after purification and centrifugation. SEM and AFM revealed the presence of hollow spherical particles, while HRTEM identified agglomerates of both small and giant fullerenes. During the synthesis, hydroxyl radicals (center dot OH) and hydroxide ions (OH-) acted as co-reactants and cleaved graphite with consequent production of fullerene-based structures. This room-temperature electrochemical approach offers scalable, bottom-up synthesis of novel carbon-based nanomaterials as well as organic compounds.

Surfactants are very important compounds that are ubiquitous in biological systems and detergents. Among them, ferrocene surfactants are a very valuable class of stimuli-responsive materials since the presence of ferrocene moiety discloses the chance to control and even modify their amphiphilic properties via a redox-induced change in the surfactant charge. In this paper, we report a new ferrocene-based surfactant: a ferrocene C-3 derivative of cholic acid, a non-classical surfactant. The title compound of this work was meant to show the significant self-assembly behaviour typical of bile salts, improved by the presence of the aromatic ferrocene subunit. We intended to demonstrate that the presence of the redox mediator should provide the derivative with sensitivity to an oxidative stimulus and control over the aggregation properties. The title compound was prepared in two steps from easily accessible precursors, and its optical properties were investigated through UV-Vis absorption spectroscopy. The determination of its critical micellar concentration and redox potential confirmed this derivative’s amphiphilic nature and its tendency to be reversibly oxidized.

To date, the potential exploitation of hybrid organic-inorganic perovskites (HOIPs) in photovoltaic technologies has been significantly hampered by their poor environmental stability. HOIP degradation can be triggered by conventional operational environments, with excessive heating and exposure to oxygen and moisture significantly reducing the performances of HOIP-based solar cells. An imperative need emerges for a thorough investigation on the impact of these factors on the HOIP stability. In this work, the degradation of methylammonium lead bromide (CH3NH3PbBr3) thin films, deposited via spin-coating on indium tin oxide (ITO) and strontium titanate (STO) substrates, was investigated by combining Raman and ultraviolet-visible (UV-Vis) absorption spectroscopy, as well as optical and fluorescence microscopy. We assessed the physical and chemical degradation of the films occurring under diverse preservation conditions, shedding light on the byproducts emerging from different degradation pathways and on the optimal HOIP preservation conditions.

In this work, an accurate modelling of the absorption spectrum and of the ground and excited state redox properties of the P1 dye - a benchmark system in p-type Dye-sensitized Solar Cells (p-DSCs) - is presented. The computed values were obtained by means of a QM/MM approach that combines a low computational cost with a proper treatment of the effects of the environment. The good agreement between our theoretical-computational estimates and the available experimental data underlines how a proper description of the redox thermodynamics of the ground and electronic excited states of the dye in a realistic environment can be provided by in silico modelling.

We report on the synthesis of two new dyes to be employed as sensitizers in p-type dye-sensitized solar cells (DSCs). The design of the two new molecules under consideration has been inspired by the state-of-art dye PMI-6 T-TPA. In particular, a specific engineering of the thiophene-based central core is here considered to favour structural planarity between an oligothiophenic pi-spacer (a sexithiophene), and the acceptor and donor units made by peryleneimide (PMI) and triphenylamine (TPA) moieties, respectively. This leads to a wide absorption in the NIR with stabilization of the HOMO energy level in the resulting dyes, as supported by TD-DFT simulations and spectroscopic characterization. When tested as sensitizers in NiOx-based p-type DSCs, A6D (with an Acceptor-pi-Donor structure) outperforms both its counterpart with a Donor-pi-Donor structure (D6D) and P1, a benchmark dye in the field of p-DSCs. With A6D dye-sensitizer the resulting DSC device presents the quite remarkable value of stabilized efficiency as high as 0.15 % when I -/I3- is employed as redox couple and nano-structured NiOx photocathode is thick less than 2 mu m and does not contain any blocking layer. Notwithstanding the panchromatic feature of the sensitizer, A6D-based devices show an average visible transmittance (AVT) of 8 %. Such a result paves the way toward the application of these types of multifunctional dyes in semi-transparent solar cells.

Hybrid organic-inorganic perovskites (HOIPs) have attracted considerable attention in the past years as photoactive materials for low-cost, high-performance photovoltaics. Polaron formation through electron-phonon coupling has been recognized as the leading mechanism governing charge carrier transport and recombination in HOIPs. In this work, two types of MAPbBr3 film samples deposited on different substrates (transparent insulating SrTiO3 and a heterostructure mimicking a functioning photovoltaic cell) were photoexcited with above-bandgap radiation at 450 nm, and the effects of illumination on the sample were analyzed in the infrared region. The infrared absorbance detected at different powers of the photoexciting laser allowed us to obtain an estimate of the characteristic decay time of photoexcited polaron population of the order of 100-1000 ns. When focusing on the absorption features of the MA molecular cation in the region of the NH stretching modes, we observed the influence of hydrogen bonding and the effect of the polaron dynamics on the cation reorientation.

Perovskite‐based photovoltaics (PV) is expected to play a central role in sustainable energy production during the next decades. Several companies are investing intensively to develop a market‐ready product with efficiency and stability rapidly improving. The craft of making perovskite solar cells (PSCs) consists in the art of thin‐film deposition, with electrodeposition (ED) representing one of the most versatile techniques available. The ED's role in the development of perovskite PV with its advantages, drawbacks, and perspectives is analyzed herein. The ED of inorganic or organic/polymeric selective contacts enables high‐efficiency devices. Moreover, by exploiting properly designed functional barriers it is possible to rely on ED for the metallization of perovskite solar cells through the deposition of copper. The latter aspect could be particularly relevant for the development of silicon/perovskite tandem PV at the TW scale. On the other hand, the ED of the active layer is less successful to date mainly due to solubility issues of the perovskite in electrochemical polar solvents.

The material produced through the electrochemical polymerization of 3′4′-DDTT has been characterized with the EQCM during the process of n-doping. The supporting electrolyte (SE) was chosen considering mainly the two characteristics of hydrophobicity (to avoid the presence of water as potential contaminant) and chemical affinity with the alkyl and aromatic moieties present in poly-3′4′-DDTT. On these bases the salt (n-C4H9)4NClO4 was selected as SE since it contains the organic molecular cation (n-C4H9)4N+ that is expected to represent the charge compensating species in poly-3′4′-DDTT during n-doping. The feature of the reversibility of the electrical current profiles originated by the process of injection/extraction of electronic charge carriers in poly-3′4′-DDTT, is not encountered in the associated EQCM data. The interpretation of the EQCM data requires the consideration of phenomena of different nature. In the present work a thorough discussion of the factors influencing the EQCM response during polymer n-doping is provided taking into account the spontaneous adsorption of cations, the eventual reorientation of poly-3′4′-DDTT on the substrate and the consequences of the chains rearrangement on the electrical polarizability of poly-3′4′-DDTT during the cycles of electrochemical n-doping and undoping.

In the present work, we have undertaken the study of the n-doping process in poly-3,3″-didodecyl-2,2′:5′,2″-terthiophene (poly-33″-DDTT) employing the electrochemical quartz crystal microbalance (EQCM). The present study aims at understanding how cathodic charge in n-doped poly-33″-DDTT is compensated. For this purpose, the in situ analysis of the variations of the polymeric mass has been considered. Poly-33″-DDTT was obtained as a thin coating onto a metallic substrate via the anodic coupling of the corresponding monomer 3,3″-didodecyl-2,2′:5′,2″-terthiophene (33″-DDTT). When subjected to electrochemical n-doping in the polarization interval -2.5 ≤ Eappl ≤ 0 V vs. Ag/Ag+, the films of poly-33″-DDTT varied their mass according to a mechanism of cations insertion during n-doping and cations extraction during polymer neutralization. In fact, the electrochemical doping of polythiophenes requires the accompanying exchange of charged species to maintain the electroneutrality within the structure of the polymer in all states of polarization. At the end of a full electrochemical cycle (consisting of the n-doping and the successive neutralization of poly-33″-DDTT), the polymer retains a fraction of the mass acquired during n-doping, thus manifesting the phenomena of mass trapping. The combined analysis of electrochemical and microgravimetric data suggests that poly-33″-DDTT in the n-doped state undergoes (or electrocatalyzes) uncontrolled electrochemical reactions that are not accompanied by mass variations.

This work reports a study of regioregular poly-3 ',4 '-didodecyl-2,2 ':5 ',2 ''-terthiophene (poly-3 ' 4 '-DDTT) deposited electrochemically onto a double-band electrode for the in situ measurement of the electrical conductance. The electrodeposition of poly-3 ' 4 '-DDTT was conducted in the potentiodynamic mode within the applied potential interval 0 <= E (appl) <= 0.9 V vs Ag/Ag+ employing an electrolyte that contained the terthiophenic monomer 3 ' 4 '-DDTT (the starting redox species). These electrochemical conditions warrant the oxidation of 3 ' 4 '-DDTT (initiation step) and prevent the oxidative degradation of the polymerization product(s). Through the adoption of conformal mapping we could calculate the electrical conductivity of the electrodeposited polymer thanks to the observation of a linear variation of conductance with the consumed charge of polymerization. The use of conformal mapping has allowed also the determination of the volume yield for the poly-3 ' 4 '-DDTT under consideration. The electrical conductivity of poly-3 ' 4 '-DDTT depended nonlinearly on the scan rate of electrodeposition and varied in the broad range 12 - 34 S cm(-1). The variability of poly-3 ' 4 '-DDTT conductivity depended on the nature of the electrodeposit which, in turn, depended on the rate of oxidative coupling (determined by the electrical current) and on the rate of precipitation (determined by the conditions of saturation in proximity of the double-band electrode).

Tandem dye-sensitized solar cell shows higher photoconversion performances with respect to parent devices with single photoactive electrode thanks to careful photocurrent matching and complementarity of electrodes optical absorption.

The electrochemical oxidation of 3 ',4 '-didodecyl-2,2 ':5 ',2 ''-terthiophene (3 ' 4 '-DDTT) at applied potential values lower than 0.8 V vs Ag/Ag+ leads to the formation of an anodic deposit that is prevalently constituted by the products of monomer coupling at positions 5 and 5 ''. Upon electrochemical cycling poly-3 ' 4 '-DDTT manifests three phenomena: the cathodic shift of the main peak of poly-3 ' 4 '-DDTT oxidation, the bathochromic shift of 60 nm for the main UV-vis absorption peak, and the IR spectral evolution consisting of the progressive increase of the signals of 2,5-substituted thiophenes at expense of the signals from 2-substituted thiophenes. The observed behavior was interpreted in terms of the presence of reactive oligomers trapped in pristine as-deposited poly-3 ' 4 '-DDTT, with the oligomers undergoing further coupling in the polymeric phase upon electrochemical cycling. This combination of findings led us to conclude that poly-3 ' 4 '-DDTT manifests solid-state polymerization. After voltammogram stabilization poly-3 ' 4 '-DDTT was electrochemically stressed. The system showed a reversible electrochemical behavior up to 0.9 V vs Ag/Ag+. A depiction of the evolution of the electronic bands in poly-3 ' 4 '-DDTT when passing from the pristine state to the electrochemically cycled state has been proposed, taking into account the combination of electrochemical and optical data.

The present review analyses the recent literature on the combined use of X-ray microscopy (XRM) and atomic force microscopy (AFM) for the multiscale characterization of Li+ (or Li) batteries (LiBs) with the aim of developing guidelines for their correlative analysis. The usefulness of XRM resides in the capability of affording non invasively in situ images of the inner parts of a LiB (an encapsulated device) with spatial resolution of dozens of nm during LiB operation. XRM is non destructive and affords the early diagnosis of LiBs degradation causes when these manifest themselves as microdeformations. The multiscale characterization of LiBs also requires AFM for visualizing the morphological/physical alterations of LiB components (anodes, cathodes, electrolyte) at the sub-nanometer level. Different to XRM, AFM necessitates of a modification of LiB working configuration since AFM uses a contacting probe whereas XRM exploits radiation-matter interactions and does not require the dissection of a LiB. A description of the working principles of the two techniques is provided to evidence which technical aspects have to be considered for achieving a meaningful correlative analysis of LiBs. In delineating new perspectives for the analysis of LiBs we will consider additional complementary techniques. Among various AFM-based techniques particular emphasis is given to electrochemical AFM (EC-AFM).

The power conversion efficiency (PCE) of NiO based perovskite solar cells has recently hit a record 22.1% with a hybrid organic-inorganic perovskite composition and a PCE above 15% in a fully inorganic configuration was achieved. Moreover, NiO processing is a mature technology, with different industrially attractive processes demonstrated in the last few years. These considerations, along with the excellent stabilities reported, clearly point towards NiO as the most efficient inorganic hole selective layer for lead halide perovskite photovoltaics, which is the topic of this review. NiO optoelectronics is discussed by analysing the different doping mechanisms, with a focus on the case of alkaline and transition metal cation dopants. Doping allows tuning the conductivity and the energy levels of NiO, improving the overall performance and adapting the material to a variety of perovskite compositions. Furthermore, we summarise the main investigations on the NiO/perovskite interface stability. In fact, the surface of NiO is commonly oxidised and reactive with perovskite, also under the effect of light, thermal and electrical stress. Interface engineering strategies should be considered aiming at long term stability and the highest efficiency. Finally, we present the main achievements in flexible, fully printed and lead-free perovskite photovoltaics which employ NiO as a layer and provide our perspective to accelerate the improvement of these technologies. Overall, we show that adequately doped and passivated NiO might be an ideal hole selective layer in every possible application of perovskite solar cells.

Deep Eutectic Solvents (DESs) are gathering growing attention as sustainable solvents in different fields ranging from synthesis to electrochemical devices. Albeit DES are widely employed, the fundamental knowledge on their interspecies relations is still partial. Understanding the chemistry of this class of green solvent is an essential step to further tune their properties. In this study, we report a detailed experimental and theoretical investigation of two choline-chloride glycerol mixtures using electrochemical, spectroscopic (Raman/Far Infrared), diffraction (X-ray) and molecular simulation methods. Remarkably different Far-infrared spectra have been surprisingly collected for the two mixtures. Differences are attributed to the deconstruction of the extended hydrogen bond network characteristic of pure glycerol and of the 1:2 mixture and absent in the glycerol-richer mixture 1:3. From the analysis of X-ray profiles, that are very well reproduced by molecular dynamics, it was found that the lack of the glycerol H-bond interactions in the glycerol-richer mixture (Ch:Gly 1:3) can be attributed to the establishment of a full coordination shell of polyalcohol molecules around the chloride anion. In the 1:2 composition the coordination is probably defective, as signaled by the FIR spectrum that significantly maintains the features observed for the precursor glycerol, and the chloride stabilization is ensured by interaction with both choline hydroxyl and electrostatic interactions.

The enhancement of photoelectrochemical conversion efficiency of p-type dye-sensitized solar cells (p-DSSCs) is necessary to build up effective tandem devices in which both anode and cathode are photoactive. The efficiency of a p-type device (2.5%) is roughly one order of magnitude lower than the n-type counterparts (13.1%), thus limiting the overall efficiency of the tandem cell, especially in terms of powered current density. This is mainly due to the recombination reaction that occurs especially at the photocathode (or Indium-doped Tin Oxide (ITO))/electrolyte interface. To minimize this phenomenon, a widely employed strategy is to deposit a compact film of NiO (acting as a blocking electrode) beneath the porous electrode. Here, we propose electrodeposition as a cheap, easy scalable and environmental-friendly approach to deposit nanometric films directly on ITO glass. The results are compared to a blocking layer made by means of sol-gel technique. Cells embodying a blocking layer substantially outperformed the reference device. Among them, BL_1.10V shows the best photoconversion efficiency (0.166%) and one of the highest values of fill factor (approaching 46%) ever reported. This is mainly due to an optimized surface roughness of the blocking layer assuring a good deposition of the porous layer. The effectiveness of the implementation of the blocking layer is further proved by means of Electrochemical Impedance Spectroscopy.

This work explores two different deposition methods to grow buffer layers of ZnxCd1−xS for application in kesterite (Cu2ZnSnS4 (CZTS)) solar cells. The introduction of the mixed sulfide of Cd and Zn in CZTS based solar cells represents an important progress due to the improved device performance and minor toxicity with respect to sole CdS. The explored techniques are the chemical bath deposition (CBD) and the precursor ink. For the CBD we focused on the inclusion of zinc into the buffer, i.e. the target solid solution, taking into account the difference in the solubilities of ZnS and CdS. In aqueous solutions the co-deposition process is controlled by various solubility equilibria with CdS precipitation representing the most favorable process. Under these circumstances the ink method here proposed is a promising approach since it is based on the thermal degradation of stable chemical precursors deposited on a dry film. In doing so, the problematic co-deposition of a mixed sulfide derived from sulfides with considerably different solubilities is circumvented. The most important advantages of this approach are the easiness and scalability of the whole process and the reduction of the amounts of toxic reagents/products.