References of "Dale, Phillip 50001445"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailPhotoelectrochemical Screening of Solar Cell Absorber Layers: Electron Transfer Kinetics and Surface Stabilization
Colombara, Diego UL; Dale, Phillip UL; Kissling, Gabriela P. et al

in Journal of Physical Chemistry C (2016)

edox electrolyte contacts offer a simple way of testing the photocurrent generation/collection efficiency in partially completed thin-film solar cells without the need to complete the entire fabrication ... [more ▼]

edox electrolyte contacts offer a simple way of testing the photocurrent generation/collection efficiency in partially completed thin-film solar cells without the need to complete the entire fabrication process. However, the development of a reliable quantitative method can be complicated by the instability of the semiconductor/electrolyte interface. In the case of Cu(In,Ga)Se2 (CIGSe) solar cells, these problems can be overcome by using samples that have undergone the next processing step in solar cell fabrication, which involves chemical bath deposition of a thin (ca. 50 nm) CdS buffer layer. The choice of redox system is also critical. The frequently used Eu3+/2+ redox couple is not suitable for reliable performance predictions since it suffers from very slow electron transfer kinetics. This leads to the buildup of photogenerated electrons near the interface, resulting in electron–hole recombination. This effect, which can be seen in the transient photocurrent response, has been quantified using intensity-modulated photocurrent spectroscopy (IMPS). The study has demonstrated that the more oxidizing Fe(CN)63–/4– redox system can be used when a CdS buffer layer is deposited on the CIGSe absorber. The wide bandgap CdS acts as a barrier to hole injection, preventing decomposition of the CIGSe and formation of surface recombination centers. The IMPS response of this system shows that there is no recombination; i.e., electron scavenging is very rapid. It is shown that measurements of the external quantum efficiency made using the Fe(CN)63–/4– redox couple with CdS-coated CIGSe layers can provide reliable predictions of the short-circuit currents of the complete solar cells. Similar results have been obtained using CdS-coated GaAs layers, suggesting that the new approach may be widely applicable. [less ▲]

Detailed reference viewed: 243 (7 UL)
Full Text
Peer Reviewed
See detailSecondary phase formation during monoclinic Cu2SnS3 growth for solar cell application
De Wild, Jessica UL; Robert, Erika UL; El Adib, Brahime et al

in Solar Energy Materials and Solar Cells (2016)

Detailed reference viewed: 187 (9 UL)
Full Text
Peer Reviewed
See detailElectrodeposition and selenization of brass/tin/germanium multilayers for Cu2Zn(Sn1-xGex)Se4 thin film photovoltaic devices
Clauwaert, Kwinten; Goossens, Maaike; De Wild, Jessica UL et al

in Electrochimica Acta (2016), 198

Detailed reference viewed: 101 (0 UL)
Full Text
Peer Reviewed
See detailOptical methodology for process monitoring of chalcopyrite photovoltaic technologies: Application to low cost Cu(In,Ga)(S,Se)2 electrodeposition based processes
Oliva, Florian; Kretzschmar, Steffen; Colombara, Diego UL et al

in Solar Energy Materials & Solar Cells (2016)

Non-destructive characterization of both single layers and completed devices are important issues for the development of efficient and low cost Cu(In,Ga)(S,Se)2 (CIGS) modules at high yields. This implies ... [more ▼]

Non-destructive characterization of both single layers and completed devices are important issues for the development of efficient and low cost Cu(In,Ga)(S,Se)2 (CIGS) modules at high yields. This implies for the need of methodologies suitable for the assessment of optical, electrical, and physico-chemical parameters that are relevant for the final device efficiency and that can be used for quality control and process monitoring at different process steps. In these applications, detection of in-homogeneities in the different layers from large area modules is especially relevant, being the presence of these inhomogeneities responsible for the existing gap between the efficiencies achieved in these technologies at cell and module levels. In this context, this work reviews the different optical methodologies that have been developed in the framework of the SCALENANO European project for the advanced assessment of the different layers in high efficiency electrodeposited – based CIGS devices. This has includes different strategies as those based on Raman scattering, Photoluminescence/Electroluminescence (PL/EL) based techniques and new photoelectrochemical based tools and firstly Raman spectroscopy is very sensitive to both composition and crystal quality parameters that are determining for device efficiency. Use of resonant Raman excitation strategies allows achieving a high sensitivity of the Raman spectra to the analysed features in the different regions of the device. This involves selection of the suitable excitation wavelength (in the broad spectral region from UV to IR) for the resonant Raman excitation of the required layer in the device. The strong increase in the intensity of the Raman peaks related to the use of resonant excitation conditions allows also decreasing the measuring time to times compatible with the implementation of these techniques at online process monitoring level. Analysed parameters include the electrical conductivity of the Al-doped ZnO window layer, the thickness of the CdS buffer layer and the chemical composition (S/(S+Se) relative content) and presence of relevant secondary phases as Cu-poor ordered vacancy compounds in the surface region of the absorbers. In addition PL/EL imaging are powerful techniques that provide direct access to the optoelectronic properties of the materials and devices. Whereas EL is performed using complete devices by injecting current in analogy to the operation of a light emitting diode, PL allows the characterization of bare absorber materials without the need for any functional or contacting layers. Moreover, semiconductor photo-electrochemistry (PEC) is a versatile technique that enables many opto-electronic properties of semiconductors to be determined. Essentially, a semiconductor on a conducting substrate placed in a solution containing redox species forms a Schottky barrier junction. The formation of such a diode enables basic semiconductor properties to be measured such as doping type, doping density, band gap and the flat band position versus the vacuum energy scale. In all these cases, quality control indicators suitable for the advanced assessment of these processes have been identified and validated for the electrodeposition-based processes developed at Nexcis Company. [less ▲]

Detailed reference viewed: 182 (13 UL)
Full Text
Peer Reviewed
See detailLaser annealing of electrodeposited CuInSe2 Semiconductor Precursors: Experiment and Modeling
Meadows, Helen UL; Misra S.; Simonds B. J. et al

in Journal of Materials Chemistry C (2016)

Detailed reference viewed: 129 (5 UL)
Full Text
Peer Reviewed
See detail13.3% efficient solution deposited Cu(In,Ga)Se 2 solar cells processed with different sodium salt sources
Berner, Ulrich; Colombara, Diego UL; De Wild, Jessica UL et al

in Progress in Photovoltaics Research and Applications (2015)

Detailed reference viewed: 255 (18 UL)
Full Text
Peer Reviewed
See detailVapour phase alkali species for Cu(In,Ga)Se2 solar cells
Berner, Ulrich; Colombara, Diego UL; Bertram, Tobias UL et al

Scientific Conference (2015, September)

Alkalis are essential in Cu(In,Ga)Se2 absorber layers for efficient solar cells. Current doping methods rely on solid state diffusion of an alkali through to the absorber layer, e.g. a thin NaF layer on ... [more ▼]

Alkalis are essential in Cu(In,Ga)Se2 absorber layers for efficient solar cells. Current doping methods rely on solid state diffusion of an alkali through to the absorber layer, e.g. a thin NaF layer on Mo or NaCl dissolved in a metal precursor ink[1]. The apparent concentration of alkali in the final absorber is determined by the initial alkali dosing and the use of an interfacial barrier to stop alkali diffusion from the substrate. Until now the vapor–absorber interface as a source or sink of alkali doping has been largely ignored. We show that device efficiency improves from 2 to 8% by gas phase Na adsorption alone. Conversely initial results show that Na can also be desorbed to the gas phase. Although these efficiencies are lower than those obtained by including Na directly in the precursor (device efficiency 13.3% [1]), the findings are relevant to all chalcogenide growers as they show that exact doping, and thus control of device efficiency, is only possible when gas phase adsorption/desorption processes are controlled. [less ▲]

Detailed reference viewed: 127 (12 UL)
Full Text
See detailCu2SnS3-based thin film solar cell from electrodeposition-annealing route
Robert, Erika UL; De Wild, Jessica UL; Dale, Phillip UL

in IEEE Proceedings (2015, June)

Cu2SnS3 is a new emerging material for thin film photovoltaics, composed of three abundant and non toxic elements. Its p-type conductivity, bandgap of 0.93 eV and absorption coefficient above 104 cm-1 ... [more ▼]

Cu2SnS3 is a new emerging material for thin film photovoltaics, composed of three abundant and non toxic elements. Its p-type conductivity, bandgap of 0.93 eV and absorption coefficient above 104 cm-1 make it a promising absorber layer for p-n heterojunction devices. In this study, the Cu2SnS3 absorber is synthesized from electroplated stacked Cu-Sn precursors further annealed in chalcogen atmosphere (S and SnS). The electroplating has been processed on upscaled 45 x 50 mm2 Mo-coated soda-lime glass substrates on which the metallic layers seem to delaminate easily from the substrate due to increased stress between them. To reduce this stress the precursors are subjected to pre-alloying treatments. The effects of pre-alloying are investigated in terms of final absorber morphology, composition and crystal structure. Precursors are annealed at 250°C and 350°C. The prealloying at 350°C is far above the melting point of Sn around 230°C and these samples show de-wetting. The as-deposited and 250°C pre-alloyed samples are processed further into absorber layers and solar cells. The finished absorber layers show mainly monoclinic Cu2SnS3. Absorbers completed into devices show a device power conversion efficiency of 0.64%. The spectral response suggests the existence of two bandgaps, consistent with previous results. [less ▲]

Detailed reference viewed: 203 (14 UL)
Full Text
See detailKesterite, Cu2ZnSn(S,Se)4, for earth abundant photovoltaics: can we make single phase thin films, and does it matter?
Dale, Phillip UL

Scientific Conference (2015, May)

In order for thin film photovoltaic devices to contribute to future renewable energy generation they must consist of earth abundant materials and be cheap to manufacture. At the heart of thin film ... [more ▼]

In order for thin film photovoltaic devices to contribute to future renewable energy generation they must consist of earth abundant materials and be cheap to manufacture. At the heart of thin film photovoltaic devices lies the p-type semiconductor absorber layer whose job is to convert incoming solar radiation into electrical charge carriers that are subsequently separated across the p-n junction. The leading earth abundant thin film absorber layer is Kesterite, Cu2Zn(Sn,Ge)(S,Se)4, which has produced laboratory scale power conversion efficiencies of around 12 %, close to the necessary efficiency for thinking about industrial production. Here, the current status of Kesterite technology will be reviewed in terms of desired and achieved properties and the synthetic challenges which must be overcome to improve overall device efficiency. Amongst the key semiconductor properties for thin film absorber layers are band gap, doping density and minority carrier life. Additionally, attention to layer integrity and the presence of detrimental secondary phases is of equal importance. The quaternary Kesterite has a rather small single phase region and multiple secondary phases are possible. Also, under normal synthesis conditions it releases two volatile species that must be taken into account for any controllable synthesis. Given these challenges, and with a perspective to depositing films on a meter squared basis, a close examination of Kesterite layer growth strategies is required. [less ▲]

Detailed reference viewed: 145 (2 UL)
Full Text
Peer Reviewed
See detailElectrodeposition of Kesterite thin films for photovoltaic applications: Quo vadis?
Colombara, Diego UL; Crossay, Alexandre UL; Vauche et al

in Physica Status Solidi A. Applications and Materials Science (2015), 212(1), 88-102

This paper aims at providing an updated overview of the main achievements in the development of solar cells based on Cu2ZnSn(S,Se)4 (CZTS(Se)) kesterite absorbers obtained by electrodeposition. Although ... [more ▼]

This paper aims at providing an updated overview of the main achievements in the development of solar cells based on Cu2ZnSn(S,Se)4 (CZTS(Se)) kesterite absorbers obtained by electrodeposition. Although undoubtedly challenging, the ultimate goal is to learn from the past works and build a solid framework for future advances in this field. What is the reason for the lower efficiency of electrodeposited CZTS(Se)-based devices (8%) compared to the world record efficiency achieved with a hydrazine-based solution approach (12.6%)? Can this gap be filled, or there are intrinsic limitations for this achievement? The review is divided into the three main electrodeposition approaches: sequential elemental layer, alloy co-deposition, and chalcogenide co-deposition. It is argued that considerable technical challenges must be overcome for the latter approach to be successfully applied. [less ▲]

Detailed reference viewed: 194 (12 UL)
See detailKesterites: Equilibria and Secondary Phase Identification
Berg, Dominik; Dale, Phillip UL

in Ito, K (Ed.) Copper zinc tin sulphide-based thin film solar cells (2015)

Detailed reference viewed: 86 (0 UL)
Full Text
Peer Reviewed
See detailCu2ZnSnSe4 device obtained by formate chemistry for metallic precursor layer fabrication
Tombolato, Sara; Berner, Ulrich Maximilian UL; Colombara, Diego UL et al

in Solar Energy (2015), 116

Detailed reference viewed: 164 (6 UL)
Full Text
Peer Reviewed
See detailDifferent Bandgaps in Cu2ZnSnSe4: A High Temperature Coevaporation Study
Redinger, Alex UL; Sendler, Jan UL; Djemour, Rabie et al

in IEEE Journal of Photovoltaics (2015), 5(2), 641-648

We present a high-temperature Cu2ZnSnSe4 coevaporation study, where solar cells with a power conversion efficiency of 7.1 have been achieved. The process is monitored with laser light scattering in order ... [more ▼]

We present a high-temperature Cu2ZnSnSe4 coevaporation study, where solar cells with a power conversion efficiency of 7.1 have been achieved. The process is monitored with laser light scattering in order to follow the incorporation of the Sn into the film. We observe the segregation of ZnSe at the Mo/CZTSe interface. Optical analysis has been carried out with photoluminescence and spectrophotometry. We observe strong band tailing and a bandgap, which is significantly lower than in other reported efficient CZTSe absorbers. The photoluminescence at room temperature is lower than the bandgap due to the existence of a large quantity of tail states. Finally, we present effects of low-temperature postannealing of the absorbers on ordering of the Cu/Zn atoms in CZTSe and solar cell parameters. We observe strong changes in all solar cell parameters upon annealing. The efficiency of the annealed devices is significantly reduced, although ordering is improved compared with ones made from nonannealed absorbers. [less ▲]

Detailed reference viewed: 131 (1 UL)
Full Text
Peer Reviewed
See detailPrediction of Photovoltaic Cu(In,Ga)Se2 p-n Device Performance by forward Bias Electrochemical Analysis of Only the p-Type Cu(In,Ga)Se2 Films
Colombara, Diego UL; Bertram, Tobias UL; Depredurand, Valérie UL et al

in Electrochemical Society Transactions (2015), 66(6), 19-25

This work is an attempt to rate the quality of Mo/Cu(In,Ga)Se2 films intended for fabrication of photovoltaic devices. The procedure is based on the simple current-voltage electrochemical analysis of the ... [more ▼]

This work is an attempt to rate the quality of Mo/Cu(In,Ga)Se2 films intended for fabrication of photovoltaic devices. The procedure is based on the simple current-voltage electrochemical analysis of the bilayer in a Eu2+/3+-containing electrolyte solution. Two series of bilayer samples were tested electrochemically, while sister samples were completed into Mo/Cu(In,Ga)Se2/CdS/i-ZnO/Al:ZnO/Ni-Al solid state devices and their current-voltage characteristics measured in the dark. A correlation was found between the reverse saturation current density of the solid state devices and an analogous parameter extracted from the electrochemical response in forward bias. While Eu2+ was found to be metastable in water posing restrictions to the application, reproducible measurements were achieved with a methanol-based solution. The intrinsic simplicity of the proposed methodology makes it particularly suitable for the implementation of a low-cost diagnostic tool. [less ▲]

Detailed reference viewed: 140 (8 UL)
Full Text
Peer Reviewed
See detailPrediction of photovoltaic p-n device short circuit current by photoelectrochemical analysis of p-type CIGSe films
Colombara, Diego UL; Crossay, Alexandre UL; Regesch, David UL et al

in Electrochemistry Communications (2014), 48

The quality control of individual semiconductor thin films during fabrication of multiple layers is important for industry and academia. The ultimate aim of this research is to predict the efficiency of p ... [more ▼]

The quality control of individual semiconductor thin films during fabrication of multiple layers is important for industry and academia. The ultimate aim of this research is to predict the efficiency of p-–n junction solar cells by photoelectrochemical analysis of the bare p-type semiconductor. A linear correlation between the photocurrent measured electrochemically on Cu(In,Ga)Se2 absorber layers through a Eu3+ electrolyte junction and short circuit current and efficiency of the corresponding solid state devices is found. However, the correlation is complicated by pronounced recombination at the semiconductor/electrolyte interface, while the solid state interface behaves more ideally. [less ▲]

Detailed reference viewed: 181 (9 UL)