Maurizio Acciarri

• Università degli Studi di Milano-Bicocca

Defects are inherent in transition metal dichalcogenides and significantly affect their chemical and physical properties. In this study, surface defect electrochemical nanopatterning is proposed as a promising method to tune in a controlled manner the electronic and functional properties of defective MoS₂ thin films. Using parallel electrochemical...

Trillion of cigarette butts are annually littered without being recycled. This work aims at valorizing the whole cigarette butts and their components (paper, filter and tobacco) into Fe‐Nx‐C electrocatalysts for oxygen reduction reaction (ORR) in acid and alkaline media. The pristine wastes were pyrolyzed at 450 °C, activated with KOH at 700 °C, bl...

The scarcity of drinking water is an increasingly pressing issue in many regions of the world, even in areas up till now considered developed. Climate change deprives many populations of the amount of water necessary for human consumption and traditional crops. Therefore, finding new water sources and making their usage more efficient and able to a...

Cu2ZnSnS4 (CZTS) is a promising absorber material to produce thin film solar cells thanks to its high absorption coefficient, low cost and low toxicity. CdS is commonly used as a buffer layer for CZTS solar cells but, beyond its toxicity, it has a nonoptimal band alignment with CZTS. ZnxSn1−xO (ZTO), based on earth-abundant and nontoxic elements an...

Following the core theme of a circular economy, a novel strategy to upcycle cigarette butt waste into platinum group metal (PGM)-free metal nitrogen carbon (M-N-C) electrocatalysts for oxygen reduction reaction (ORR) is presented. The experimental route was composed of (i) the transformation of the powdered cigarette butts into carbonaceous char vi...

Many efforts are currently focused on materials with responsive features for neural-inspired devices. Different approaches are followed, based on various mechanisms – from ferroelectric switching to structural phase changes, from magnetic tunnel junctions to metal filament formation. Here we analyze an alternative strategy based on an unconventiona...

We report the effect of the quantum dot aspect ratio on the sub‐gap absorption properties of GaAs/AlGaAs quantum dot intermediate band solar cells. We have grown AlGaAs solar cells containing GaAs quantum dots made by droplet epitaxy. This technique allows the realization of strain‐free nanostructures with lattice matched materials, enabling the po...

Pure sulfide kesterite (Cu2ZnSnS4) is one of the most promising emerging photovoltaic technologies thanks to its excellent absorption coefficient, cost-effectiveness, and environmental sustainability. However, record efficiencies are not exceeding 11% due to several issues, such as absorber defects or a nonoptimal band alignment with the toxic but...

In article number 2201082, Simone Rossi, Fabio Pezzoli and co‐workers present an all‐optical approach to engineer the strength of the so‐called Rashba effect emerging in biased germanium quantum wells. Their results demonstrate that the spin–orbit interaction can be modified through optical pumping, eventually changing the spin polarization. These...

We investigate samples of compositionally disordered potassium-based perovskite single crystals with different composition and stoichiometry. The dielectric and Raman response is inspected over the nominal cubic-to-tetragonal long-range phase transition. The comparison between results shows that the occurrence of the phase transition is controlled...

The Rashba effect in Ge/Si0.15Ge0.85 multiple quantum wells embedded in a p‐i‐n diode is studied through polarization and time‐resolved photoluminescence. In addition to a sizeable redshift arising from the quantum‐confined Stark effect, a threefold enhancement of the circular polarization degree of the direct transition is obtained by increasing t...

In the last few decades, the attention of scientific community has been driven toward the research on renewable energies. In particular, the photovoltaic (PV) thin-film technology has been widely explored to provide suitable candidates as top cells for tandem architectures, with the purpose of enhancing current PV efficiencies. One of the most stud...

The Rashba effect in Ge/Si$_{0.15}$Ge$_{0.85}$ multiple quantum wells embedded in a p-i-n diode is studied through polarization and time-resolved photoluminescence. In addition to a sizeable redshift arising from the quantum-confined Stark effect, a threefold enhancement of the circular polarization degree of the direct transition is obtained by in...

Universities are today seen as living labs for the creation of knowledge with the aim of transferring it to society. The integration of sustainability is a critical point in this context, as solutions for problems experienced in society can be experimented with regarding physical aspects, such as Solid Waste Management (SWM), and efficiency in ener...

The use of glassceramics in photocatalysis is an attractive option for the realization of smart optical fibers and self-cleaning windows. Here we present the photocatalytic activity of germanosilicate glasses embedding Ga2O3 nanocrystals prepared by batch melting and glass heat treatment. The owdered material is used for UV-assisted degradation of...

In current days, the research in the photovoltaic field aims to find and investigate cheap thin-film materials based on earth-abundant element suitable for terawatt era. To this purpose Cu2ZnSnS4 (CZTS) has been widely studied in the last decade, being structurally analogous to the well-documented Cu(In,Ga)Se2 but featuring inexpensive and abundant...

The purpose of the study was to investigate the presence of mascara deposits on polymeric siloxane-hydrogel contact lenses (CLs) after in vivo 8 h of wear and to compare the affinity to mascara of two siloxane-hydrogels through in vitro contamination tests. The siloxane-hydrogel CLs were the Filcon V monthly replacement OPEN30 and the Delefilcon A...

In this work, Cu-Zn-Sn (CZT) is co-electrodeposited onto a flexible Mo substrate exploiting an alkaline bath (pH 10). The plating solution is studied by cyclic voltammetry, highlighting the effects of potassium pyrophosphate (K4P2O7) and EDTA-Na2 on the electrochemical behavior and stability of the metallic ionic species. The optimized synthesis re...

This paper contributes to the existing literature in proposing an integrated approach to water management and energy renewable production in a fragile environment. After the 2004 tsunami, in many outer islands in The Republic of Maldives, the lens freshwater natural reservoir was deeply damaged. Currently, the populations of rural atolls use rainwa...

Gallium incorporation in silicate glasses gives rise to compounds in which the nucleation and growth of Ga-oxide nanostructures can be designer controlled so as to obtain a number of functional properties for photonic applications. However, despite planar geometry pertains to a large part of modern technology, no information is available yet on the...

In the present study, an ethylene glycol-based electrolyte is used to electrodeposit copper onto zinc for the synthesis of the Zn/Cu/Sn stack, precursor of Cu2ZnSnS4. The employed solution contains diethanolamine (DEA) which supports the formation of amine-complexes, whose features are studied by UV-vis absorption, ESI-MS, and FTIR measurements, pr...

The cover image is based on the Research Article A European proficiency test on thin‐film tandem photovoltaic devices by Elena Salis et al., https://doi.org/10.1002/pip.3322.

The PV research is nowadays focused on finding low cost and easily processable thin-film materials, trying to move towards lighter and more versatile technologies. Among them, Cu2ZnSnS4 (CZTS) drew the attention of the scientific community thanks to its structural similarity to the already reported and well-studied Cu(In,Ga)Se2 but with the great a...

A round‐robin proficiency test (RR PT) on thin‐film multi‐junction (MJ) photovoltaic (PV) cells was run between 13 laboratories within the European project CHEETAH. Five encapsulated PV cells were circulated to participants for being tested at Standard Test Conditions (STC). Three cells were a‐Si/μc‐Si tandem PV devices, each of which had a differe...

Quantum dot solar cells are based on the concept of harvesting different parts of the solar light spectrum with a single, cheap semiconductor by simply changing the size of the nanoparticles. Of the many compositions explored, germanium is one of the most interesting as it has the major advantage of a large Bohr radius, which allows for the fabrica...

A chloride-free solution based on ethylene glycol was shown to be suitable for the electrodeposition of copper onto zinc, allowing the fabrication of a Mo/Zn/Cu/Sn metallic precursor stack. The addition of diethanolamine (DEA) played an essential role in minimizing displacement reactions by shifting copper reduction towards a more negative potentia...

We investigate effects of metal droplets on the In incorporation in InGaN epilayers grown at low temperature (450 C) by plasma assisted molecular beam epitaxy. We find a strong reduction of the In incorporation when the surface is covered by metal droplets. The such reduction increases with the droplet density and the droplet surface coverage. We e...

The demand of new responsive materials is continuously growing in several areas as a result of approaching physical limits in technologies which now call for a drastic change of strategy. Here we report on memory responsive oxide-in-oxide nanostructured films obtained by radio-frequency sputtering of 7.5Li2O−2.5Na2O−20Ga2O3−45GeO2−25SiO2 (mol%) gla...

Kesterite compound Cu2ZnSnS4 is the most promising next leader in the chalcogenide thin films technology as it is based on earth‐abundant elements. In this work, kesterite thin films were prepared with a wet chemistry method by using a DMSO solution containing thiourea and acetylacetone, without further addition of vapour sulfur compounds to obtain...

Purpose: Photostress recovery time (PSRT) is the time required for the macula to return to its normal functioning after the bleaching of cone photopigments due to light exposure, usually white. This work investigates the role of macular pigment (MP) as an optical filter which attenuates photostress by analyses of PSRT at different wavelengths. Meth...

It is well known that the major constraints to the efficiency of photovoltaic devices come from the generation of heat. In this context, thermoelectric generators have been proposed as a viable heat recovery solution, leading to an increase of the overall efficiency. Within this kind of hybrid solution, the photovoltaic and thermoelectric parts can...

Solar cell thermal recovery has recently attracted more and more attention as a viable solution to increase photovoltaic efficiency. However, the convenience of the implementation of such a strategy is bound to the precise evaluation of the recoverable thermal power and to a proper definition of the losses occurring within the solar device. In this...

It is well known that the major constrain to the efficiency of photovoltaic (PV) devices comes from the generation of unused heat. In this context, thermoelectric generators have been proposed as a viable heat recovery solution, leading to an increase of the overall efficiency. Within this kind of hybrid solutions, the PV and TEG parts can be eithe...

The growth dynamics of Ga(In)N semiconductors by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) at low temperatures (T = 450 °C) is here investigated. The presence of droplets at the growth surface strongly affects the adatom incorporation dynamics, making the growth rate a decreasing function of the metal flux impinging on the surface. We explain...

Photoluminescence spectra of pure CIGS thin films with different Ga in-depth gradients are systematically investigated. Pure Na-free films are prepared with an innovative hybrid deposition technique, whose optical luminescence emission is analyzed as a function of the depth and is correlated to the radiative intrinsic defects of the material. Final...

We present a comprehensive overview on a new hybrid sputtering-evaporation (HSE) system for the deposition of Cu(In,Ga) Se2 (CIGS) thin-films aimed at photovoltaic applications. Such a technique employs the sputtering process to deposit the metal precursors on suitable rotating transfer cylinders, from which they are subsequently evaporated, in Se...

Solar cell thermal recovery is recently attracting more and more attention in the research community as a viable solution to increase photovoltaic efficiency. However the convenience of the implementation of such strategy is bound to the precise evaluation of the recoverable thermal power, and to a proper definition of the losses occurring within t...

We investigate the effect of the formation of metal droplets on the growth dynamics of InGaN by Plasma-Assisted Molecular Beam Epitaxy (PAMBE) at low temperatures (T = 450{\deg}C). We find that the presence of droplets on the growth surface strongly affects the adatom incorporation dynamics, making the growth rate a decreasing function of the overa...

ZnS is a versatile, abundant and eco-friendly semiconductor material employed in many applications. In the present manuscript, ZnS thin films were grown by one of the most simple and scalable vacuum method, that is the room temperature radio frequency sputtering technique. An extensive characterization has been performed by atomic force microscopy,...

An attractive solution for the preparation of In and Ga free chalcogenides which may allow terawatt range photovoltaic (PV) applications relies on I 2-II-IV-VI 4 species, such as copper zinc tin sulfide/selenide. A further alternative belonging to this class of materials is Cu 2 MnSnS 4 (CMTS), which consists of abundant and non-toxic elements and...

Earth abundant and low cost Cu2MnSnS4 (CMTS) thin films were grown by a two-step vacuum approach: metal precursor stacks grown by thermal evaporation were heat treated in elemental sulfur vapors. Cu-poor/Mn-rich CMTS samples with large grain size and good layer compactness were obtained by sulfurization at 585 °C with an initial step at 115 °C to e...

In the thin film solar cells domain, copper indium galium (di)selenide (CIGS) is a material with well-established photovoltaic purpose. Here the presence of a suitable [Ga]/([Ga]þ[In]) (GGI) in-depth profile has proved to play a key role in the performance of cells. The implementation of a routine method based on reliable but easily available exper...

Earth abundant Cu2MnSnS4 (CMTS) absorbers for thin film solar cells were grown for the first time by a two-step vacuum approach. Metal precursors deposited on Mo-coated soda lime glass by thermal evaporation were annealed in sulfur vapors. Two series of CMTS samples were prepared to evaluate the effect of both the precursor stack (thickness and ord...

We report preliminary results on InGaP/InGaAs/Ge photovoltaic cells for concentrated terrestrial applications, monolithically integrated on engineered Si(001) substrates. Cells deposited on planar Ge/Si(001) epilayers, grown by plasma-enhanced chemical vapor deposition, provide good efficiency and spectral response, despite the small thickness of t...

Cu2ZnSnS4 (CZTS) thin films and solar cells were successfully prepared using a new process based on spray pyrolysis technique. The main advantage of the proposed process is the avoiding of sulphurisation process at high temperature and in toxic gases like H2S. X-ray diffraction studies and Raman spectroscopy confirmed the formation of good-quality...

Objectives: This article compares the optical performance of soft contact lenses (CLs) treated with multipurpose or hydrogen peroxide care systems. Methods: The investigated care systems were (1) 3% hydrogen peroxide solution Oxysept (Abbot Medical Optics, Abbott Park, IL) and (2) multipurpose solution Regard (Vita Research, Ariccia, Italy). Thr...

In recent years, multi-crystalline solar grade silicon (mc-SoG-Si), instead of expensive electronic-grade Si, is being considered in photovoltaic industry for production of solar modules. These materials usually contain a comparable amount of acceptors (e.g. boron) and donors (e.g. phosphorus) and are therefore called compensated mc-SoG-Si. The ele...

In this work, a new hybrid sputtering–evaporation system providing a scalable process for deposition of Cu(In,Ga)Se2 (CIGS) layers is presented. The growth apparatus has been designed and realized to fit a size suitable for direct industrial transfer. In this process the metal precursors are first of all sputtered on rotating transfer devices, then...

A possible approach to raise the efficiency of single-junction solar cells is to couple them with thermoelectric generators (TEGs). It was shown that TEG contribution to the output power is basically ruled by the characteristics of the photovoltaic (PV) material. In this study, we present a quantitative model that correlates the efficiency of the h...

Cu2ZnSnS4 (CZTS) absorber layers grown by sputtering were investigated by photoluminescence before and after the chemical bath deposition of CdS in order to evaluate the possible passivation of point defects by Cd atoms at the absorber/buffer layer interface. According to the literature, a broad emission around 1.21 eV was observed at low temperatu...

Exploitation of solar energy conversion has become a fundamental aspect of satisfying a growing demand for energy. Thus, improvement of the efficiency of conversion in photovoltaic (PV) devices is highly desirable to further pro-mote this source. Because it is well known that the most relevant efficiency constraint, especially for single-junction s...

Due to the many advantages of aluminum doped zinc oxide (AZO) as an alternative to indium tin oxide (ITO), the optical and electrical properties of AZO thin films deposited on large substrates by D.C. pulsed magnetron sputtering have been investigated in view of future industrial applications. In order to evaluate the effectiveness of AZO thin film...

In this paper crucial factors for the deposition of AZO/i-ZnO bi-layers to be used as front contact in chalcogenide photovoltaics are considered, with emphasis on effect of the deposition parameters on the electrical and optical properties. Thereby, a systematic study focused on the substrate temperature, substrate to target distance and i-ZnO and...

Thin film solar cells based on Cu(In,Ga)Se2 (CIGS) yield, up to now, a maximum photovoltaic conversion efficiency if CdS deposited by chemical bath deposition is used as buffer layer. However, due to the disadvantages of CdS (like the toxicity classification of Cd, the non-vacuum nature of the chemical bath deposition and the absorption of blue lig...

Cu2ZnSnS4 (CZTS) thin films are grown by a two step process aimed for low toxicity requirements and relatively low temperature annealing in S2 atmosphere. The chemical process developed is based on the metal complexation plus the thermolysis of thiourea to form a highly condensed precursor film. The reagents used are copper acetate, zinc acetate an...

In this study, we have investigated the Hall majority carrier mobility of p‐type, compensated multicrystalline solar grade silicon (SoG‐Si) wafers for solar cells in the temperature range 70–373 K. At low temperature (~70 K) the difference in the mobilities measured for the compensated and the uncompensated reference samples is the highest, and the...

Despite long and extensive research effort the interest in transparent and conducting oxide (TCO) layers has not ceased. The reason is the ever increasing economic interest in these materials as many optoelectronic devices rely on high quality TCO layers. Transparent conductive oxide possess low resistivity, exhibit good adherence to many substrate...

In the last decade, the fast increase of the global energy consumption, mainly related to the strong economic growth in the Far East, and the progressive depletion of the fossil fuels induced a run-up in the world oil price. Both these economic concerns and the growing global pollution pointed out that a transition toward renewable energies is mand...

In the last decades, the run-up in both the fossil fuel prices and the related global warming turned the attention towards environmentally clean alternative energy resources. Among them, solar photovoltaics is a reliable choice to tackle the strong increase of the global energy demand. The development of low cost and efficient solar cells has been...

We report the fabrication procedure and the characterization of an Al0.3Ga0.7As solar cell containing high-density GaAs strain-free quantum dots grown by droplet epitaxy. The production of photocurrent when two sub-bandgap energy photons are absorbed simultaneously is demonstrated. The high quality of the quantum dot/barrier pair, allowed by the hi...

Today, after more than 70 years of continued progress on silicon technology, about 85% of cumulative installed photovolatic (PV) modules are based on crystalline silicon (c-Si). PV devices based on silicon are the most common solar cells currently being produced, and it is mainly due to silicon technology that the PV has grown by 40% per year over...

Intermediate band photovoltaics is one of the so-called third generation photovoltaic device designs proposed to increase the efficiency of solar cells. It involves the creation of an intermediate band (IB) inside a semiconductor band gap, that can allow sub-bandgap photon absorption without degrading the output voltage of the device. One possibili...

The first examples of thiocyanate-free thiophene-substituted Ru(ii) cyclometalated complexes, based on thiophene-derived 2-(2,4-difluorophenyl)pyridine ligands, are presented and investigated as photosensitizers in DSCs. Upon thiophene substitution the complexes presented enhanced optical properties compared to the reference dye with no thiophene s...

In this work, an alternative approach for CIGS thin film growth has been tested, which is different from the common co-evaporation process. Such approach consists of sputtering deposition of the metal elements combined with selenium evaporation. This new and easily scalable procedure allows deposition time of the CIGS layer lower than 15 minutes an...

Electrical properties of grain boundaries grown by Czochralski process were studied by microwave phase shift (μW-PS) and electron beam induced current (EBIC), before and after gold diffusion at 700°C. As-grown samples had similar doping levels determined by four-point probe measurements but somewhat different oxygen concentrations, obtained by Four...

In view of large-scale exploitation of CuIn1-xGaxSe2 (CIGS) solar cells for photovoltaic energy conversion, it would be quite important not only to increase the conversion efficiency, but also to reduce the thickness of CIGS layer in order to decrease the use of rare and expensive elements, especially Indium. In this work we perform a full study of...

This work reports recent results related to Cu(In,Ga)Se2 solar cells obtained using an alternative approach for CIGS growth. Such original approach consists of sputtering deposition of the metal elements combined with selenium co-evaporation, which allows deposition time of the CIGS layer lower than 30 min, matching industrial application requireme...

Photovoltaic concentrating cells (CPV) and light emitting devices (LED) present analogous problems in the optimization of the front contact metal grid. In fact, both devices have to manage high current densities, can present similar semiconductor structures based on III-V compounds, have small dimensions and similar manufacturing process. In both c...

The deposition of sub-stoichiometric silicon rich oxide (SRO) is the first step to obtain well ordered silicon Quantum Dots (QDs) in a dielectric matrix. This structure is used also for third generation photovoltaic devices operating in a tandem architecture. A precise control and assessment of the stoichiometry of these films is crucial to tune th...

In this paper we report the experimental results obtained from the manufacturing and characterization of III-V solar cells based on single junction, dual junction and triple junction structures. The main solar cell materials are GaAs and (Al)InGaP compounds. A test plan for qualification of “bare” solar cells for concentration systems is presented...

In this paper we report a new method for Cu(In,Ga)Se2 deposition for solar cell application. Differently from the common co-evaporation process, an alterative approach for thin film Cu(In,Ga)Se2 has been tested: the sputtering deposition of metal elements combined with the selenium evaporation. We have studied the relationships between the growth p...

The chemistry of the interactions between point defects and impurities is discussed by considering first the general thermodynamic and kinetic aspects of these reactions, deserving major attention to the identity of of the stable chemical species eventually formed and to the boundary conditions for diffusion controlled and reaction controlled inter...

Oxygen precipitation creates centers of recombination of carriers. Therefore, oxygen concentration and its chemical configuration must be controlled. In this study, the oxygen distribution on a multicrystalline silicon ingot produced by directional solidification of upgraded metallurgical silicon is investigated. The highest amount of oxygen was de...

The conductivity of single grain boundaries of electronic grade, Bridgman grown polycrystalline silicon samples was measured using the dc polarization technique with the aim of detecting any influence on the carrier transport regime resulting from the segregation of oxygen and carbon, which, by themselves, should behave as electrically inactive imp...

It is well known that the sharp, room temperature luminescence emission at 1.54 μm from dislocated silicon has set off a great interest for this material in view of its applications in the third window of optical telecommunications. For this reason the dislocation related luminescence in silicon addressed recently a number of investigation aimed at...

a b s t r a c t This work reports on the optical and electrical characterization of crystalline silicon based solar modules encapsulated with ethylene-vinyl-acetate layers (that is the encapsulating matrix used nowadays by the photovoltaic industry) doped with a single europium complex whose sensitized region is broadened due to the presence of a c...

This paper reports results about aluminium gallium indium phosphide (AlGaInP) based solar cells, in order to define their physical properties for applications in high efficiency devices. In fact, used as top junction, AlGaInP is a promising material for the realization of high efficiency solar cells with more than three junctions. Here AlGaInP sing...

Rubrene, perylene, -quaterthiophene, and tetracene single crystals were grown and placed between indium-tin-oxide and Al electrodes; the current-voltage characteristics of the so-fabricated two-terminal organic devices were measured at ambient conditions under solar simulator illumination. While rubrene single crystals do not exhibit any pho-tovolt...

p-doped hydrogenated nanocrystalline silicon (p-nc-Si:H) is one of the most critical layers in thin film silicon solar cells. LEPECVD is a new technique for the growth of nc-Si at high growth rate without compromising the layer quality, using a dense but low energy plasma. Thin p-nc-Si:H layers are grown on glass and ZnO:Al coated glass and their s...

Low-energy plasma-enhanced chemical vapour deposition (LEPECVD) is a new technique for growth of hydrogenated microcrystalline silicon (μc-Si:H) at high growth rate. For all existing growing techniques, a silane dilution threshold exists below which the material’s electronic and optical properties are crystalline-like and above which they are amorp...