cabecera

Nanostructured Solar Cells

RESEARCH

DEPARTMENTS
QuantMat
RESEARCH GROUPS
solarcells
nanomaterialsenergy
2DMATERIALS
theoryquantum
Atomicmanipulation

DESCRIPTION

The Laboratory for Nanostructured Solar Cells (LaNaSC) develops nano- and micro-structures of chalcopyrite-type semiconductors (Cu(In,Ga)Se2) for application in photovoltaic energy conversion.

We currently follow three research lines:

  • Development of growth methods for chalcopyrite nanostructures e. quantum dots and nanowires. The goal is to combine the excellent light absorbing properties of chalcopyrite-type materials with the quantum properties of nanostructured materials, and thereby provide a pathway for the enhancement of power conversion efficiencies of photovoltaic devices beyond the Shockley-Queisser limit.
  • Development of advanced thin film solar cells by the implementation of micro- and nanostructures.
  • Development and application of scanning probe microscopy techniques for the characterization of solar cell materials and light-induced phenomena at the nanometer scale.

The laboratory is equipped with various materials preparation facilities consisting in a molecular beam epitaxy (MBE) setup for the growth of nanostructured chalcopyrite-type semiconductors, a hybrid sputter system for Cu(In,Ga)Se2, Mo, and ZnO, and an evaporation system for Cu(In,Ga)Se2 thin films.

The lab also operates an ultra-high vacuum scanning probe microscope, combining STM, AFM, and KPFM facilities with surface photovoltage methods to study light-induced phenomena at the nanometer scale.

We are always open for new team members. If you are interested in joining us and applying for external funding (i.e. Marie Curie, FCT, etc.), please contact Sascha by email.

RESEARCH PROJECTS

Chalcopyrite, Cu(In,Ga)Se2 (CIGSe), materials have excellent light absorbing properties and are used in the thin-film solar cell technology with the highest power conversion efficiency. We are working with these materials at the nanometer length scale with the goal to increase power conversion efficiencies.

We aim to develop growth methods for chalcopyrite nanostructures, i.e. quantum dots and nanowires. The goal is to combine the excellent light absorbing properties of chalcopyrite-type materials with the quantum properties of nanostructured materials, and thereby provide a pathway for the enhancement of power conversion efficiencies of photovoltaic devices beyond the Shockley-Queisser limit. We use a molecular beam epitaxy (MBE) system to evaporate the constituent elements (Cu, In, Ga, Se) onto epitaxial substrates, where at low evaporation rates and thin coverage the formation of nano-sized crystallites occurs.

project 1

Molecular Beam Epitaxy system for Cu(In,Ga)Se2 nanostructure growth

Project leader:Sascha Sadewasser
Team members: Kamal Abderrafi, Rodrigo Ribeiro

Chalcopyrite, Cu(In,Ga)Se2 (CIGSe), materials have excellent light absorbing properties and are used in the thin-film solar cell technology with the highest power conversion efficiency. We are aiming at incorporating novel concepts to improve thin film solar cells using nano- and micrometer structures ointo the device structure.

Currently, we focus our research efforts on two approaches:

  • We develop micro solar cells for micro-concentrator solar cell applications. The goal is to develop highly efficient solar cells with a significant reduction in usage of absorber materials. By concentrating the sunlight onto micrometer sized CIGSe solar cells, the materials consumption of the solar cell material can be significantly reduced, leading to cost improvements. We combine cleanroom technology with the growth of CIGSe materials to obtain the micro solar cells.
  • Development of nanostructures for chalcopyrite thin-film solar cells. The goal is to use passivation and light management techniques to improve solar cell performance. We use cleanroom technologies to introduce a passivation layer with contact holes in between the back contact and the absorber layer. This reduces back contact recombination and allows for thinner absorber layers, leading to cost savings for solar cell devices.

Project leader: Sascha Sadewasser
Team members: Kamal Abderrafi, David Correia, Paulo Salvador

We use ultrahigh vacuum scanning probe microscopy (UHV-SPM) methods to characterize the physical properties of chalcopyrite nanostructures and solar cell materials at the nanoscale.

Scanning probe methods include regular atomic force microscopy, Kelvin probe force microscopy, surface photovoltage measurements and scanning tunneling microscopy. We are especially interested in the interaction of light with solar cell materials at the nanoscale.

project 1

Scanning probe microscopy system

Project leader: Sascha Sadewasser
Team members: Nicoleta Nicoara

PUBLICATIONS

2015

P.M.P. Salomé H. Rodriguez-Alvarez, Sadewasser

Incorporation of alkali metals in chalcogenide solar cells (Journal Article)

Solar Energy Materials & Solar Cells, 143 , pp. 9, 2015.

(Links | BibTeX)

Piotr Szaniawski Pedro Salomé, Viktor Fjällström Tobias Törndaht Uwe Zimmermann Marika Edoff

Influence of varying Cu content on growth and performance of Ga-graded Cu(In,Ga)Se2 solar Cells (Journal Article)

IEEE J. PV , 5 , pp. 1775, 2015.

(Links | BibTeX)

da da A. Abelenda M. Sánchez, Ribeiro Fernandes Salomé Cunha Leitão Silva González

Anomalous persistent photoconductivity in Cu2ZnSnS4 thin films and solar cells (Journal Article)

Solar Energy Materials & Solar Cells , 137 , pp. 164, 2015.

(Links | BibTeX)

V. Fjällström P. Szaniawski, Vermang Salomé Rostvall Zimmermann; M.Edoff,

Recovery after potential induced degradation of Cu(In,Ga)Se2 solar cells with CdS and Zn(O,S) buffer layers (Journal Article)

IEEE J. Photovoltaics , 5 , pp. 664, 2015.

(BibTeX)

2014

A. Strózecka J. Li, Schürmann Schulze Corso Schulz Ch. Lotze Sadewasser Franke; Pascual,

Electroluminescence of copper-nitride nanocrystals (Journal Article)

Phys. Rev. B, 90 , 2014.

(Links | BibTeX)

da J. P. Teixeira R. A. Sousa, Sousa Cunha Fernandes Salomé; Leitão,

Radiative transitions in highly doped and compensated chalcopyrites and kesterites: The case of Cu2ZnSnS4 (Journal Article)

Phys. Rev. B, 90 , 2014.

(Links | BibTeX)

Ch. Frisk Ch. Platzer Björkman, Olsson Szaniawski Wätjen Fjällström Salomé Edoff

Optimizing Ga-profiles for highly efficient Cu(In,Ga)Se2 thin film solar cells in simple and complex defect models (Journal Article)

J. Phys. D: Appl. Phys. , 47 , 2014.

(Links | BibTeX)

B. Vermang J.T. Wätjen, Ch. Frisk Fjällström Rostvall Edoff Salomé Borme Nicoara Sadewasser

Introduction of Si PERC rear contacting design to boost efficiency of Cu(In,Ga)Se2 solar cells (Journal Article)

IEEE J. Photovoltaics, 4 , pp. 1644, 2014.

(Links | BibTeX)

R. Baier C. Leendertz, Abou-Ras M.Ch. Lux-Steiner; Sadewasser,

Properties of electronic potential barriers at grain boundaries in Cu(In,Ga)Se2 thin films (Journal Article)

Sol. Energy Mat. Sol. Cells , 130 , pp. 124, 2014.

(Links | BibTeX)

da J.P. Teixeira R.A. Sousa, Sousa Cunha Fernandes Salomé González; Leitão,

Comparison of fluctuating potentials and DAP transitions in a Cu-poor Cu2ZnSnS4 based solar cell (Journal Article)

Appl. Phys. Lett. , 105 , 2014.

(Links | BibTeX)

P. M. P. Salomé P. A. Fernandes, Leitão Sousa Teixeira; Cunha,

Secondary crystalline phases identification in Cu2ZnSnSe4 thin films: contributions from Raman scattering and photoluminescence (Journal Article)

Journal of Material Science , 49 , 2014.

(Links | BibTeX)

H. Rodriguez-Alvarez, Sadewasser

A 1D Fickian diffusional model for the formation of the double Ga-gradient in three-stage Cu(In,Ga)Se2 (Journal Article)

J. Appl. Phys. , 115 , 2014.

(Links | BibTeX)

da H.V. Alberto R.C. Vil, Gil Piroto Duarte Vieira Weidinger Leitão Cunha Sousa Teixeira Fernandes Salomé Timmo Loorits Amato H.Luetkens Prokscha Suter; Salman,

Muonium states in Cu2ZnSnS4 solar cell material (Journal Article)

J. Phys.: Conference Series, 551 , 2014.

(Links | BibTeX)

2013

H. Rodriguez-Alvarez R. Mainz, Caballero Abou-Ras Klaus Gledhill Weber Kaufmann Schock

Real-time study of Ga diffusion processes during the formation of Cu(In,Ga)Se2: the role of Cu and Na content (Journal Article)

Sol. Energy Mat. Sol. Cells , 116 , pp. 102, 2013.

(Links | BibTeX)

H. Rodriguez-Alvarez N. Barreau, Kaufmann Weber Klaus Painchaud Schock Mainz

Recrystallization of Cu(In,Ga)Se2 thin films studied by X-ray diffraction (Journal Article)

Acta Materialia , 61 , pp. 4347, 2013.

(Links | BibTeX)

H. Rodriguez-Alvarez A. Weber, Lauche Kaufmann Rissom Greiner Klaus Unold Genzel Schock Mainz

Formation of CuInSe2 and Cu(In,Ga)Se2 thin-films by three thermal co-evaporation: a real-time X-ray diffraction and fluorescence study (Journal Article)

Adv. Energy Mater, 2013.

(Links | BibTeX)

Th. Dittrich A. Gonzáles, Rada Rissom Zillner Sadewasser M.Ch. Lux-Steiner

Comparative study of Cu(In,Ga)Se2 / CdS and Cu(In,Ga)Se2 / In2S3 systems by surface photovoltage techniques (Journal Article)

Thin Solid Films, 563 , pp. 357, 2013.

(Links | BibTeX)

2012

J.R. O’Dea L.M. Brown, Hoepker Marohn; Sadewasser,

Scanning probe microscopy of solar cells: From inorganic thin films to organic photovoltaics (Journal Article)

Materials Research Society Bulletin , 37 , pp. 642, 2012.

(Links | BibTeX)

J. Bastek N.A. Stolwijk, Wuerz Eicke Albert; Sadewasser,

Zinc diffusion in polycrystalline Cu(In,Ga)Se2 and single-crystal CuInSe2 layers” (Journal Article)

Appl. Phys. Lett. , 101 , 2012.

(Links | BibTeX)

S.S. Schmidt D. Abou-Ras, Sadewasser Yin Feng Yan

Electrostatic potentials at Cu(In,Ga)Se2 grain boundaries - experiment and simulations (Journal Article)

Phys. Rev. Lett. , 109 , 2012.

(Links | BibTeX)

R. Baier J. Lehmann, Lehmann Th. Rissom Ch.A. Kaufmann Schwarzmann Rosenwaks M.Ch. Lux-Steiner; Sadewasser,

Electronic properties of grain boundaries in Cu(In,Ga)Se2 thin films with various Ga-contents (Journal Article)

Sol. Energy Mat. Sol. Cells , 103 , pp. 86, 2012.

(Links | BibTeX)

F. Mesa W. Chamorro, Vallejo Baier Th. Dittrich Grimm M.Ch. Lux-Steiner; Sadewasser,

Junction formation of Cu3BiS3 investigated by Kelvin probe force microscopy and surface photovoltage measurements (Journal Article)

Beilstein J. Nanotechnol, 3 , pp. 277-284, 2012.

(Links | BibTeX)

R. Baier C. Leendertz, M.Ch. Lux-Steiner; Sadewasser,

Towards quantitative Kelvin probe force microscopy of nanoscale potential distributions (Journal Article)

Phys. Rev. B , 85 , pp. 165436, 2012.

(Links | BibTeX)

2011

M. Afshar S. Sadewasser, Albert Lehmann Abou-Ras Fuertes Marrón Rockett Räsänen; Lux-Steiner, M.Ch.

Chalcopyrite Semiconductors for Quantum Well Solar Cells (Journal Article)

Advanced Energy Materials, 1 , pp. 1109, 2011.

(Links | BibTeX)

GROUP LEADER

Sascha_Sadewasser

THE TEAM

Nicoleta Nicoara
Staff Researcher

Pedro Anacleto
Research Engineer

Kamal Abderrafi
Research Fellow

Umesh Gomes
Research Fellow

DESCRIPTION

The Laboratory for Nanostructured Solar Cells (LaNaSC) develops nano- and micro-structures of chalcopyrite-type semiconductors (Cu(In,Ga)Se2) for application in photovoltaic energy conversion.

We currently follow three research lines:

  • Development of growth methods for chalcopyrite nanostructures e. quantum dots and nanowires. The goal is to combine the excellent light absorbing properties of chalcopyrite-type materials with the quantum properties of nanostructured materials, and thereby provide a pathway for the enhancement of power conversion efficiencies of photovoltaic devices beyond the Shockley-Queisser limit.
  • Development of advanced thin film solar cells by the implementation of micro- and nanostructures.
  • Development and application of scanning probe microscopy techniques for the characterization of solar cell materials and light-induced phenomena at the nanometer scale.

The laboratory is equipped with various materials preparation facilities consisting in a molecular beam epitaxy (MBE) setup for the growth of nanostructured chalcopyrite-type semiconductors, a hybrid sputter system for Cu(In,Ga)Se2, Mo, and ZnO, and an evaporation system for Cu(In,Ga)Se2 thin films.

The lab also operates an ultra-high vacuum scanning probe microscope, combining STM, AFM, and KPFM facilities with surface photovoltage methods to study light-induced phenomena at the nanometer scale.

We are always open for new team members. If you are interested in joining us and applying for external funding (i.e. Marie Curie, FCT, etc.), please contact Sascha by email.

RESEARCH PROJECTS

Chalcopyrite, Cu(In,Ga)Se2 (CIGSe), materials have excellent light absorbing properties and are used in the thin-film solar cell technology with the highest power conversion efficiency. We are working with these materials at the nanometer length scale with the goal to increase power conversion efficiencies.

We aim to develop growth methods for chalcopyrite nanostructures, i.e. quantum dots and nanowires. The goal is to combine the excellent light absorbing properties of chalcopyrite-type materials with the quantum properties of nanostructured materials, and thereby provide a pathway for the enhancement of power conversion efficiencies of photovoltaic devices beyond the Shockley-Queisser limit. We use a molecular beam epitaxy (MBE) system to evaporate the constituent elements (Cu, In, Ga, Se) onto epitaxial substrates, where at low evaporation rates and thin coverage the formation of nano-sized crystallites occurs.

project 1

Molecular Beam Epitaxy system for Cu(In,Ga)Se2 nanostructure growth

Project leader:Sascha Sadewasser
Team members: Kamal Abderrafi, Rodrigo Ribeiro

Chalcopyrite, Cu(In,Ga)Se2 (CIGSe), materials have excellent light absorbing properties and are used in the thin-film solar cell technology with the highest power conversion efficiency. We are aiming at incorporating novel concepts to improve thin film solar cells using nano- and micrometer structures ointo the device structure.

Currently, we focus our research efforts on two approaches:

  • We develop micro solar cells for micro-concentrator solar cell applications. The goal is to develop highly efficient solar cells with a significant reduction in usage of absorber materials. By concentrating the sunlight onto micrometer sized CIGSe solar cells, the materials consumption of the solar cell material can be significantly reduced, leading to cost improvements. We combine cleanroom technology with the growth of CIGSe materials to obtain the micro solar cells.
  • Development of nanostructures for chalcopyrite thin-film solar cells. The goal is to use passivation and light management techniques to improve solar cell performance. We use cleanroom technologies to introduce a passivation layer with contact holes in between the back contact and the absorber layer. This reduces back contact recombination and allows for thinner absorber layers, leading to cost savings for solar cell devices.

Project leader: Sascha Sadewasser
Team members: Kamal Abderrafi, David Correia, Paulo Salvador

We use ultrahigh vacuum scanning probe microscopy (UHV-SPM) methods to characterize the physical properties of chalcopyrite nanostructures and solar cell materials at the nanoscale.

Scanning probe methods include regular atomic force microscopy, Kelvin probe force microscopy, surface photovoltage measurements and scanning tunneling microscopy. We are especially interested in the interaction of light with solar cell materials at the nanoscale.

project 1

Scanning probe microscopy system

Project leader: Sascha Sadewasser
Team members: Nicoleta Nicoara

PUBLICATIONS

2015

P.M.P. Salomé H. Rodriguez-Alvarez, Sadewasser

Incorporation of alkali metals in chalcogenide solar cells (Journal Article)

Solar Energy Materials & Solar Cells, 143 , pp. 9, 2015.

(Links | BibTeX)

Piotr Szaniawski Pedro Salomé, Viktor Fjällström Tobias Törndaht Uwe Zimmermann Marika Edoff

Influence of varying Cu content on growth and performance of Ga-graded Cu(In,Ga)Se2 solar Cells (Journal Article)

IEEE J. PV , 5 , pp. 1775, 2015.

(Links | BibTeX)

da da A. Abelenda M. Sánchez, Ribeiro Fernandes Salomé Cunha Leitão Silva González

Anomalous persistent photoconductivity in Cu2ZnSnS4 thin films and solar cells (Journal Article)

Solar Energy Materials & Solar Cells , 137 , pp. 164, 2015.

(Links | BibTeX)

V. Fjällström P. Szaniawski, Vermang Salomé Rostvall Zimmermann; M.Edoff,

Recovery after potential induced degradation of Cu(In,Ga)Se2 solar cells with CdS and Zn(O,S) buffer layers (Journal Article)

IEEE J. Photovoltaics , 5 , pp. 664, 2015.

(BibTeX)

2014

A. Strózecka J. Li, Schürmann Schulze Corso Schulz Ch. Lotze Sadewasser Franke; Pascual,

Electroluminescence of copper-nitride nanocrystals (Journal Article)

Phys. Rev. B, 90 , 2014.

(Links | BibTeX)

da J. P. Teixeira R. A. Sousa, Sousa Cunha Fernandes Salomé; Leitão,

Radiative transitions in highly doped and compensated chalcopyrites and kesterites: The case of Cu2ZnSnS4 (Journal Article)

Phys. Rev. B, 90 , 2014.

(Links | BibTeX)

Ch. Frisk Ch. Platzer Björkman, Olsson Szaniawski Wätjen Fjällström Salomé Edoff

Optimizing Ga-profiles for highly efficient Cu(In,Ga)Se2 thin film solar cells in simple and complex defect models (Journal Article)

J. Phys. D: Appl. Phys. , 47 , 2014.

(Links | BibTeX)

B. Vermang J.T. Wätjen, Ch. Frisk Fjällström Rostvall Edoff Salomé Borme Nicoara Sadewasser

Introduction of Si PERC rear contacting design to boost efficiency of Cu(In,Ga)Se2 solar cells (Journal Article)

IEEE J. Photovoltaics, 4 , pp. 1644, 2014.

(Links | BibTeX)

R. Baier C. Leendertz, Abou-Ras M.Ch. Lux-Steiner; Sadewasser,

Properties of electronic potential barriers at grain boundaries in Cu(In,Ga)Se2 thin films (Journal Article)

Sol. Energy Mat. Sol. Cells , 130 , pp. 124, 2014.

(Links | BibTeX)

da J.P. Teixeira R.A. Sousa, Sousa Cunha Fernandes Salomé González; Leitão,

Comparison of fluctuating potentials and DAP transitions in a Cu-poor Cu2ZnSnS4 based solar cell (Journal Article)

Appl. Phys. Lett. , 105 , 2014.

(Links | BibTeX)

P. M. P. Salomé P. A. Fernandes, Leitão Sousa Teixeira; Cunha,

Secondary crystalline phases identification in Cu2ZnSnSe4 thin films: contributions from Raman scattering and photoluminescence (Journal Article)

Journal of Material Science , 49 , 2014.

(Links | BibTeX)

H. Rodriguez-Alvarez, Sadewasser

A 1D Fickian diffusional model for the formation of the double Ga-gradient in three-stage Cu(In,Ga)Se2 (Journal Article)

J. Appl. Phys. , 115 , 2014.

(Links | BibTeX)

da H.V. Alberto R.C. Vil, Gil Piroto Duarte Vieira Weidinger Leitão Cunha Sousa Teixeira Fernandes Salomé Timmo Loorits Amato H.Luetkens Prokscha Suter; Salman,

Muonium states in Cu2ZnSnS4 solar cell material (Journal Article)

J. Phys.: Conference Series, 551 , 2014.

(Links | BibTeX)

2013

H. Rodriguez-Alvarez R. Mainz, Caballero Abou-Ras Klaus Gledhill Weber Kaufmann Schock

Real-time study of Ga diffusion processes during the formation of Cu(In,Ga)Se2: the role of Cu and Na content (Journal Article)

Sol. Energy Mat. Sol. Cells , 116 , pp. 102, 2013.

(Links | BibTeX)

H. Rodriguez-Alvarez N. Barreau, Kaufmann Weber Klaus Painchaud Schock Mainz

Recrystallization of Cu(In,Ga)Se2 thin films studied by X-ray diffraction (Journal Article)

Acta Materialia , 61 , pp. 4347, 2013.

(Links | BibTeX)

H. Rodriguez-Alvarez A. Weber, Lauche Kaufmann Rissom Greiner Klaus Unold Genzel Schock Mainz

Formation of CuInSe2 and Cu(In,Ga)Se2 thin-films by three thermal co-evaporation: a real-time X-ray diffraction and fluorescence study (Journal Article)

Adv. Energy Mater, 2013.

(Links | BibTeX)

Th. Dittrich A. Gonzáles, Rada Rissom Zillner Sadewasser M.Ch. Lux-Steiner

Comparative study of Cu(In,Ga)Se2 / CdS and Cu(In,Ga)Se2 / In2S3 systems by surface photovoltage techniques (Journal Article)

Thin Solid Films, 563 , pp. 357, 2013.

(Links | BibTeX)

2012

J.R. O’Dea L.M. Brown, Hoepker Marohn; Sadewasser,

Scanning probe microscopy of solar cells: From inorganic thin films to organic photovoltaics (Journal Article)

Materials Research Society Bulletin , 37 , pp. 642, 2012.

(Links | BibTeX)

J. Bastek N.A. Stolwijk, Wuerz Eicke Albert; Sadewasser,

Zinc diffusion in polycrystalline Cu(In,Ga)Se2 and single-crystal CuInSe2 layers” (Journal Article)

Appl. Phys. Lett. , 101 , 2012.

(Links | BibTeX)

S.S. Schmidt D. Abou-Ras, Sadewasser Yin Feng Yan

Electrostatic potentials at Cu(In,Ga)Se2 grain boundaries - experiment and simulations (Journal Article)

Phys. Rev. Lett. , 109 , 2012.

(Links | BibTeX)

R. Baier J. Lehmann, Lehmann Th. Rissom Ch.A. Kaufmann Schwarzmann Rosenwaks M.Ch. Lux-Steiner; Sadewasser,

Electronic properties of grain boundaries in Cu(In,Ga)Se2 thin films with various Ga-contents (Journal Article)

Sol. Energy Mat. Sol. Cells , 103 , pp. 86, 2012.

(Links | BibTeX)

F. Mesa W. Chamorro, Vallejo Baier Th. Dittrich Grimm M.Ch. Lux-Steiner; Sadewasser,

Junction formation of Cu3BiS3 investigated by Kelvin probe force microscopy and surface photovoltage measurements (Journal Article)

Beilstein J. Nanotechnol, 3 , pp. 277-284, 2012.

(Links | BibTeX)

R. Baier C. Leendertz, M.Ch. Lux-Steiner; Sadewasser,

Towards quantitative Kelvin probe force microscopy of nanoscale potential distributions (Journal Article)

Phys. Rev. B , 85 , pp. 165436, 2012.

(Links | BibTeX)

2011

M. Afshar S. Sadewasser, Albert Lehmann Abou-Ras Fuertes Marrón Rockett Räsänen; Lux-Steiner, M.Ch.

Chalcopyrite Semiconductors for Quantum Well Solar Cells (Journal Article)

Advanced Energy Materials, 1 , pp. 1109, 2011.

(Links | BibTeX)

GROUP LEADER

Sascha_Sadewasser

THE TEAM

Nicoleta Nicoara
Staff Researcher

Pedro Anacleto
Research Engineer

Kamal Abderrafi
Research Fellow

Umesh Gomes
Research Fellow

RESEARCH

DEPARTMENTS
QuantMat
RESEARCH GROUPS
solarcells
nanomaterialsenergy
2DMATERIALS
theoryquantum
Atomicmanipulation