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See detailElectronic and compositional properties of the rear-side of stoichiometric CuInSe2 absorbers
Kameni Boumenou, Christian UL; Elisabeth, Amala; Babbe, Finn et al

in Progress in Photovoltaics (2020)

In-depth understanding and subsequent optimization of the contact layers in thin film solar cells are of high importance in order to reduce the amount of nonradiative recombination and thereby improve ... [more ▼]

In-depth understanding and subsequent optimization of the contact layers in thin film solar cells are of high importance in order to reduce the amount of nonradiative recombination and thereby improve device performance. In this work, the buried MoSe2/CuInSe2 interface of stoichiometric absorbers is investigated with scanning tunneling spectroscopy and Kelvin probe force microscopy combined with compositional measurements acquired via photo-electron spectroscopy after a mechanical lift-off process. We find that the local density of states, as measured with scanning tunneling spectroscopy, is similar to the front-side of ultra-high vacuum annealed CISe absorbers. The grain boundaries exhibit a weak upward band bending, opposite to Cu-poor CuGaSe2, and we measure an increased Cu accumulation at the rear CISe surface compared to the bulk composition and a non-zero concentration of Cu on the Mo-side. Grazing incidence X-ray diffraction measurements corroborate that a small amount of a CuxSe secondary phase is present at the MoSe2/CuInSe2 interface in contrast to reports on Cu-poor material. Our findings shed new light into the complex interface formation of CuInSe2-based thin film solar cells grown under Cu-rich conditions. [less ▲]

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See detailAbsorber composition: A critical parameter for the effectiveness of heat treatments in chalcopyrite solar cells
Sood, Mohit UL; Elanzeery, Hossam UL; Adeleye, Damilola UL et al

in Progress in Photovoltaics (2020)

Post-device heat treatment (HT) in chalcopyrite [Cu(In,Ga)(S,Se)2] solar cells is known to improve the performance of the devices. However, this HT is only beneficial for devices made with absorbers grown ... [more ▼]

Post-device heat treatment (HT) in chalcopyrite [Cu(In,Ga)(S,Se)2] solar cells is known to improve the performance of the devices. However, this HT is only beneficial for devices made with absorbers grown under Cu-poor conditions but not under Cu excess.. We present a systematic study to understand the effects of HT on CuInSe2 and CuInS2 solar cells. The study is performed for CuInSe2 solar cells grown under Cu-rich and Cu-poor chemical potential prepared with both CdS and Zn(O,S) buffer layers. In addition, we also study Cu-rich CuInS2 solar cells prepared with the suitable Zn(O,S) buffer layer. For Cu-poor selenide device low-temperature HT leads to passivation of bulk, whereas in Cu-rich devices no such passivation was observed. The Cu-rich devices are hampered by a large shunt. The HT decreases shunt resistance in Cu-rich selenides, whereas it increases shunt resistance in Cu-rich sulfides.. The origin of these changes in device performance was investigated with capacitance-voltage measurement which shows the considerable decrease in carrier concentration with HT in Cu-poor CuInSe2, and temperature dependent current-voltage measurements show the presence of barrier for minority carriers. Together with numerical simulations, these findings support a highly-doped interfacial p+ layer device model in Cu-rich selenide absorbers and explain the discrepancy between Cu-poor and Curich device performance. Our findings provide insights into how the same treatment can have a completely different effect on the device depending on the composition of the absorber. [less ▲]

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See detailCan we see defects in capacitance measurements of thin‐film solar cells ?
Werner, Florian UL; Babbe, Finn UL; Elanzeery, Hossam UL et al

in Progress in Photovoltaics (2019), 27

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See detailHigh‐performance low bandgap thin film solar cells for tandem applications
Elanzeery, Hossam UL; Babbe, Finn UL; Melchiorre, Michele UL et al

in Progress in Photovoltaics (2018)

Thin film tandem solar cells provide a promising approach to achieve high efficiencies. These tandem cells require at least a bottom low bandgap and an upper high bandgap solar cell. In this contribution ... [more ▼]

Thin film tandem solar cells provide a promising approach to achieve high efficiencies. These tandem cells require at least a bottom low bandgap and an upper high bandgap solar cell. In this contribution, 2 high‐performance Cu(In,Ga)Se2 cells with bandgaps as low as 1.04 and 1.07 eV are presented. These cells have shown certified efficiencies of 15.7% and 16.6% respectively. Measuring these cells under a 780‐nm longpass filter, corresponding to the bandgap of a typical top cell in tandem applications (1.57 eV), they achieved efficiencies of 7.9% and 8.3%. Admittance measurements showed no recombination active deep defects. One additional high‐performance CuInSe2 thin film solar cell with bandgap of 0.95 eV and efficiency of 14.1% is presented. All 3 cells have the potential to be integrated as bottom low bandgap cells in thin film tandem applications achieving efficiencies around 24% stacked with an efficient high bandgap top cell. [less ▲]

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See detailVisualizing the performance loss of solar cells by IR thermography — an evaluation study on CIGS with artificially induced defects
Vetter, Andreas; Babbe, Finn UL; Hofbeck, Bernhard et al

in Progress in Photovoltaics (2016), 24(7), 1001-1008

Local electric defects may result in considerable performance losses in solar cells. Infrared (IR) thermography is one im- portant tool to detect these defects on photovoltaic modules. Qualitative ... [more ▼]

Local electric defects may result in considerable performance losses in solar cells. Infrared (IR) thermography is one im- portant tool to detect these defects on photovoltaic modules. Qualitative interpretation of IR images has been carried out successfully, but quantitative interpretation has been hampered by the lack of “calibration” defects. The aims of this study are to (i) establish methods to induce well-defined electric defects in thin-film solar cells serving as “calibration” defects and to (ii) assess the accuracy of IR imaging methods by using these artificially induced defects. This approach paves the way for improving quality control methods based on imaging in photovoltaic. We created ohmic defects (“shunts”) by using a focused ion beam and weak diodes (“interface shunts”) by applying a femto-second laser at rather low power on copper indium gallium selenide cells. The defects can be induced precisely and reproducibly, and the severity of the defects on the electrical performance can be well adjusted by focused ion beam/laser parameters. The successive assess- ment of the IR measurement (ILIT-Voc) revealed that this method can predict the losses in Pmpp (maximal power extract- able) with a mean error of below 10%. [less ▲]

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See detailCu-rich CuInSe2 solar cells with a Cu-poor surface
Aida, Yasuhiro UL; Depredurand, Valérie UL; Larsen, Jes K. UL et al

in PROGRESS IN PHOTOVOLTAICS (2015), 23

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See detailSolution-based processing of Cu(In,Ga)Se2 absorber layers for 11% efficiency solar cells via a metallic intermediate
Berner, Ulrich Maximilian UL; Widenmeyer, Markus

in Progress in Photovoltaics (2014)

In this work, a low cost solution-based method for the deposition of uniform Cu-In-Ga layers compatible with roll-to-roll processing is described. As ink system we use metal carboxylates dissolved in a ... [more ▼]

In this work, a low cost solution-based method for the deposition of uniform Cu-In-Ga layers compatible with roll-to-roll processing is described. As ink system we use metal carboxylates dissolved in a mixture of a nitrogen containing base and an alcohol. This solution can be coated homogeneously under inert atmosphere using a doctor blade technique. With this method and appropriate precursor concentrations, crack-free metal layers with dry-film thicknesses of more than 700 nm can be deposited in one fast step. For the controlled film formation during the drying of the solvents a flow channel has been used to improve the evaporative mass transport and the convective gas flows of any unwanted organic species. Due to the absence of organic binders with high molecular weight, this step allows the formation of virtually pure metal layers. Elementary analyses of the dried thin films reveal less than 5 wt% of carbon residues at 200°C. In situ X-ray diffraction data of the drying step show the formation of Cu-In-Ga alloys. The subsequent processing of Cu(In,Ga)Se2 chalcopyrites with evaporated elemental selenium takes place in a separate tube oven under inert atmosphere. Photoelectric measurements of cells with CdS buffer and ZnO window layer reveal a short-circuit current of 29 mA/cm2, an open-circuit voltage of 533 mV, and a fill factor of 0.69 under standard conditions. Thus efficiencies of up to 11% on 0.5 cm2 area without antireflective coating have been achieved. [less ▲]

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See detailCu2ZnSnSe4 thin film solar cells produced via co-evaporation and annealing including a SnSe2 capping layer
Redinger, Alex UL; Mousel, Marina; Djemour, Rabie et al

in PROGRESS IN PHOTOVOLTAICS (2014), 22(1), 51-57

Cu2ZnSnSe4 (CZTSe) thin film solar cells have been produced via co-evaporation followed by a high-temperature annealing. In order to reduce the decomposition of the CZTSe, a SnSe2 capping layer has been ... [more ▼]

Cu2ZnSnSe4 (CZTSe) thin film solar cells have been produced via co-evaporation followed by a high-temperature annealing. In order to reduce the decomposition of the CZTSe, a SnSe2 capping layer has been evaporated onto the absorber prior to the high-temperature treatment. This eliminates the Sn losses due to SnSe evaporation. A solar cell efficiency of 5.1 could be achieved with this method. Moreover, the device does not suffer from high series resistance, and the dominant recombination pathway is situated in the absorber bulk. Finally different illumination conditions (white light, red light, and yellow light) reveal a strong loss in fill factor if no carriers are generated in the CdS buffer layer. This effect, known as red-kink effect, has also been observed in the closely related Cu(In,Ga)Se-2 thin film solar cells. Copyright (c) 2013 John Wiley Sons, Ltd. [less ▲]

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See detailThe electronic structure of chalcopyrites - bands, point defects and grain boundaries
Siebentritt, Susanne UL; Igalson, Malgorzata; Persson, Clas et al

in Progress in Photovoltaics (2010), 18(6), 390-410

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See detailCu2ZnSnSe4 thin film solar cells produced by selenisation of magnetron sputtered precursors
Zoppi, Guillaume; Forbes, Ian; Miles, Robert W. et al

in Progress in Photovoltaics (2009), 17(5), 315-319

Detailed reference viewed: 126 (0 UL)