S. Binetti

• PhD in Chemistry
• FULL Professor in Physical Chemistry at Università degli Studi di Milano-Bicocca

Perovskite solar cells (PSCs) have burst into photovoltaic (PV) research, revolutionising it and demonstrating that they can achieve performances comparable to technologies already on the market. Despite that, the major...

Cu2ZnSnS4 (CZTS) is a narrow band gap, non-toxic, and environmentally friendly semiconductor with important properties for photovoltaic and electro-/photo- catalytic applications. In this study, we report on the synthesis of...

Dangerous emerging water micropollutants like Diclofenac are harming ecosystems all over the planet, and immediate action is needed. The large bandgap photocatalysts conventionally used to degrade them need to be more efficient. Cu2ZnSnS4, a well-known light absorber in photovoltaics with a bandgap of 1.5 eV, can efficiently harvest an abundant por...

Heat is an inexhaustible source of energy, and it can be exploited by thermoelectronics to produce electrical power or electrical responses. The search for a low-cost thermoelectric material that could achieve high efficiencies and can also be straightforwardly scalable has turned significant attention to the halide perovskite family. Here, we repo...

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...

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...

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...

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...

Lead halide perovskites have been revolutionary in the last decade in many optoelectronic sectors. Their bismuth-based counterparts have been considered a good alternative thanks to their composition of earth-abundant elements, good chemical stability, and low toxicity. Moreover, their electronic structure is in a quasi-zero-dimensional (0D) config...

In recent decades, many technological advances have been enabled by nanoscale phenomena, giving rise to the field of nanotechnology. In particular, unique optical and electronic phenomena occur on length scales less than 10 nanometres, which enable novel applications. Halide perovskites have been the focus of intense research on their optoelectroni...

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...

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...

Earth-abundant and non-toxic Kesterite-based Cu2ZnSnS4 (CZTS) thin film solar cells are successfully fabricated on flexible Molybdenum (Mo) foil substrates by an electrodeposition-annealing route. A well-adherent, densely packed, homogeneous, compact, and mirror-like CZT precursor is initially produced through electrodeposition by using a rotating...

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...

We perform redundant x-ray diffraction versus temperature experiments in bulk transparent KTN. We find a violation of the standard perovskite cubic-to-tetragonal symmetry breaking at the Curie point in the form of an orthorhombic cell distortion. The lattice distortion spans coherently macroscopic volumes of the sample and is characterized by a neg...

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...

Photovoltaics is a promising technology to produce sustainable energy, thanks to the high amount of energy emitted by the sun. One way of having solar cells with low production costs is to apply thin-film technology and with earth-abundant raw materials. A keen interest is arising in kesterite compounds, which are chalcogenides composed of abundant...

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...

We investigate low-temperature (<200 °C) plasma-enhanced chemical vapor deposition (PECVD) for the formation of p–n junctions. Compared to the standard diffusion or implantation processes, silicon growth at low temperature by PECVD ensures a lower thermal budget and a better control of the doping profile. We previously demonstrated the successful g...

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...

The most common multi-junction solar cell arrangement employs the InGaP/InGaAs/Ge configuration, which is usually exploited for high-efficiency space applications. We here test the reliability of a triple-junction device with an innovative low-thickness and flexible configuration: this is investigation is aimed at providing its main macroscopic fea...

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...

At the end of 2017 roughly 1.8% of the worldwide electricity came from solar photovoltaics (PV), which is foreseen to have a key role in all major future energy scenarios with an installed capacity around 5 TW by 2050. Despite silicon solar cells currently rule the PV market, the extremely more versatile thin film-based devices (mainly Cu(In,Ga)Se2...

During their employment in space applications, InGaP/InGaAs/Ge‐based multijunction solar cells undergo strong particle bombardments that decrease their performances. As InGaP is more resistant to radiation, the whole device is usually designed in “top‐limited” configuration. Then the development of high‐efficiency and reliable devices needs standar...

Fine powders composed of tellurium grains of average size <10 nm were produced by dry vibration milling combined with liquid-phase sedimentation techniques, starting from polycrystalline powders with average grain diameter of ca. 30 μm. Nanocomposite films were obtained by binding the nanosized tellurium grains with poly(methyl methacrylate). Raman...

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...

One of the key factors for the success of CdTe solar cells is the so-called "activation" treatment, consisting in depositing a CdCl 2 film on the CdTe layer and subsequent annealing it in air. Recent studies have found MgCl 2 as a good alternative. In this work we have studied devices (exceeding 14% efficiency) prepared by low-substrate temperature...

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,...

The adduct between Tris[3-(trifluoromethylhydroxymethilene)-d-camphorate]europium(III) and 4,4’-Bis(N,N-dimethylamino)benzophenone (EABP) presents an absorption band in the visible region that the neat reagents do not display, making this system interesting as an antenna system devoted to an efficient absorption in the visible region. The UV–Vis sp...

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...

In recent years, research on thin film photovoltaic cells is focusing on the development of inexpensive, earth abundant and environmentally benign materials [1]. CZT(S,Se) (Cu 2 ZnSn(S,Se) 4 ) thin films meet this unlike the present commercial photovoltaic thin films CIG(S,Se) (Cu(In,Ga)(S,Se)2) and CdTe. The crystal structure of CZT(S,Se) is obtai...

Earth abundant Cu 2 ZnSnSe 4 (CZTSe) thin films solar cells were fabricated on flexible molybdenum (Mo) foil substrate through an electrochemical approach. After co-electroplating from single electrolyte, Cu-Zn-Sn (CZT) precursor was selenized in quartz tube furnace at 550 • C for 15 minutes in Ar atmosphere with the presence of elemental selenium...

Earth abundant Cu2ZnSnSe4 (CZTSe) thin films solar cells were fabricated on flexible molybdenum (Mo) foil substrate through an electrochemical approach. After co-electroplating from single electrolyte, Cu-Zn-Sn (CZT) precursor was selenized in quartz tube furnace at 550°C for 15 minutes in Ar atmosphere with the presence of elemental selenium in or...

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...

In n-type Czochralski silicon (Cz-Si) wafer, swirl shaped regions with low lifetime (known as striations) can cause degradation up to 1% absolute or even more in homojunction industrial solar cells. Nevertheless, the nature of the defects responsible for the occurrence of these striations is still unclear. In this work, n-type Cz-Si solar cell prec...

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...

Owing to the very brittle nature of the tellurium powder, nanoscopic grains with average size of 4.8nm were produced by dry vibration milling technique using a Mixer mill apparatus. A novel material was obtained by binding the nanosized tellurium grains with poly(methyl methacrylate) (PMMA). The morphology, elemental composition, and structural pro...

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...

Cu2ZnSnSe4 films were prepared by selenization of metallic precursors obtained by a new wet process involving metal formates. Cu(HCOO)2 and Zn(HCOO)2 were used as copper and zinc sources respectively, while tin was introduced as a methoxide. The elemental analysis of the resulting absorber layers revealed a very low carbon content (less than 0.2 wt...

Multicrystalline Silicon was textured with picosecond laser. Different laser wavelengths (λ = 1064, 532, 355 nm) where compared regarding laser-induced damage. We found that λ = 355 nm picosecond radiation resulted in shallower defect-reach region

Electrodeposition followed by sulfurization could be a favourable process for the fabrication of the CZTS thin film solar cells. Here we attempt to fabricate CZTS thin films from co-electrodeposited precursors of Cu-Zn-Sn with various compositions from Cu-poor, Zn-rich to Cu-rich, Zn-poor. Different characterization methods like XRD, SEM (EDS), and...

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...

Nanostructured films composed of silicon crystallites dispersed in an hydrogenated amorphous silicon carbon matrix have been deposited by plasma enhanced chemical vapour deposition from silane-methane mixtures diluted in hydrogen by varying the rf power. Compositional, structural, optical and photoconductivity properties of the films have been inve...

It is widely known that Photoluminescence (PL) and Infrared (IR) spectroscopies are among the experimental tools extensively used in the last decades for the study of impurities and defects in silicon for both microelectronic and photovoltaic applications. This review paper reports the main historical achievements and recent developments obtained i...

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...

Mn2+ doped ZnS nanoparticles (ZnS:Mn2þ NPs) are non-toxic systems known for their attractive light emitting properties. This paper discusses the luminescence properties of ZnS:Mn2+ NPs prepared by wet chemical synthesis with the objective of using them as down-shifters. A modification of the incident solar spectrum inducing improved exploitation of...

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...

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...

Light-induced degradation (LID) due to boron-oxygen complex formation seriously diminishes the efficiency of p-type solar cells. The influence of dopants concentration, net doping and oxygen on the degradation process is investigated using a large variety of B and P compensated mc-Si ingots. Our experiments indicate that the trend of LID depends on...

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...

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...

Photovoltaics is the most promising technology for the future of green energy production. To fully realize the potential use of photovoltaic technology, low manufacturing cost and high working photoconversion efficiency must be obtained. Light trapping by metal nanoparticles is an attractive strategy in thin film as well as in bulk silicon solar ce...

The technology involved in the realization of InGaP/InGaAs/Ge triple junction solar cells is well known and state of the art efficiencies above 30% in AM0 conditions have been achieved. To further improve conversion efficiency of multi-junction solar cells, many solutions have been proposed, mainly involving an increase of the number of junctions b...

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...

A broad band with a fine structure on the higher energy side has been commonly observed in photoluminescence at 4.2 K from compensated Si for solar cells involving P donors and B acceptors on the order of 1016 cm−3. We calculated the theoretical spectrum of donor−acceptor (DA) pair luminescence from the density distribution of pairs as a function o...