Solar Energy Technologies Program Peer Review Routes for Rapid Synthesis of CuGa x In 1-x Se 2 Absorbers Tim Anderson University of Florida Chemical Engineering Department [email protected]May 27, 2010 Program Team : PV DICTRA • Atomic Mobilities • Chemical Potentials Seek CIGS Pathway High-rate, high-quality, low temperature Phase Diagrams Thermodynamic Properties CIGS Formation Pathways & Kinetics HT-XRD • Pathways • Rates • Mobilities Pathway Prediction ThermoCalc • Equilibria • G(T,P) database
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1 | Program Name or Ancillary Text eere.energy.gov
Solar Energy Technologies Program Peer Review
Routes for Rapid Synthesis of CuGaxIn1-xSe2 Absorbers
Tim AndersonUniversity of FloridaChemical Engineering [email protected] 27, 2010
Program Team : PV
DICTRA• Atomic Mobilities
• Chemical Potentials
Seek CIGS Pathway
High-rate, high-quality,low temperature
Phase Diagrams
ThermodynamicProperties
CIGS FormationPathways & Kinetics
HT-XRD• Pathways• Rates• Mobilities
PathwayPrediction
ThermoCalc• Equilibria• G(T,P) database
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• Total budget: $760,863 – DOE share: $599,556 – Contractor share: $161,911
• Funding received FY09: $48,684
• Funding received FY10: $79,941 (4/30/10)
Timeline
Budget
Barriers
Project lead: Tim AndersonCollaborators
Dr. Andrew Payzant, ORNLDr. Carelyn Campbell, NIST
Industry PartnersGlobal Solar NanoSolarISET Solyndra
Partners
Overview
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Challenges and Barriers
Challenge: Lower Cost - $/Wp
Materials Costs (~50%)Processing CostsCapitalization largest cost
Increase Throughput high rate synthesislower temperaturescale-up
National Solar Technology Roadmap for CIGS PV calls for absorber synthesis rates of “30–40 μm/h and <1 μm CIGS absorber thickness” by 2015 or <2 min processing time
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10
8
6
4
2
0M
eta
ls r
ate
s (Å
/s)
30
20
10
0
Se ra
te (Å
/s)
Se
In
GaCu
In
1st stage 2nd stage 3rd stage
-10 0 10 20 30 40 50 60
Run time (min)
Ga
400 °C
600 °COpenshutter
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Relevance: Project and Phase 1 Objectives:
• Determine reaction pathway for synthesis of CuGaSe2, CuInSe2, and CuInxGa1-xSe2 from basic precursor structures using HT-XRDa) From basic precursor structuresb) From industry provided precursors
• Develop a thermodynamic model describing the contained Cu-In-Ga-Se ternary phase diagrams
Develop thermodynamic description of Cu-In-Se andCu-Ga-Se ternary phase diagrams
• Build diffusion mobility database to quantitatively predict synthesis ratesBuild diffusion mobility database for the Cu-In, Cu-Ga, and Ga-In binaries
• Transfer understanding to industry collaborators– Effect of annealing on grain size and texture and Ga distribution– Assess the feasibility of sub-2 min reaction time for CIGS synthesis– Support process scalinga) Effect of annealing on grain sizeb) Assess feasibility of <2 min reaction time for absorber synthesis
Phase 1
Phase 1
Phase 1
Phase 1
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X-raytube
PSD
Chamber
In Out(He)
Capton/Be window
CW inout
Sampleholder
Panalytical Philips X’pert System
SurroundingHeater
High Temperature Materials Laboratory (ORNL)
Precursorsample
Selenium powder
Graphite Dome
Scintag-HTXRD also available
Approach to Pathway Analysis
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Progress: HT-XRD StudiesBinary Precursors
In2Se3 (slow)
CuSe2/CuSe/Cu2-xSe(fast)
Cu7Se4/CuSe/Cu2-xSe(slow)
In4Se3/In2Se3(slow)
Ga2Se3 (fast)
GaSe (fast)
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Approach to Developing Phase Diagrams
Data
Thermochemical& Equilibrium
Structure
• Literature• Measurements -EMF• First Principles• Estimation
• Significant differences in rate• Co-evaporation is high rate
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652.2Κ605.8Κ
UF11-2 (Cu/In= 1.260)
Before After
Approaches to High Rate Synthesis Pathway: CIS/CuSex Nanoparticles
Use eutectic valley orperitectic reactions to
liquid phase assist growth
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Temperature Ramp Annealwith Se Overpressure
220
260
Tm of Se
2θ
330380
CuSe2CuSe2 Se
CuSe2 CuSe + L CuSe β-Cu2-x Se + L
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100
60027
CIS(Cubic)
• Ramp anneal shows initial cubic CIS phase and CuSe2• Tetragonal CIS forms at 260 °C• Peritectic reactions occur consistent with the phase diagram
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Collaborations
Industry PartnersGlobal SolarInternational Solar Electric Technology (ISET)NanoSolarSolyndra
Perform studies on industry provided samples to address their absorber synthesis processes. Share results of our research.
CollaborationsDr. Andrew Payzant, ORNL, Senior Member of R&D Staff
Collaborator in HT-XRD studies; leader of Diffraction User Center (DUC) in High Temperature Materials Laboratory-UF team DUC user.
Dr. Carelyn Campbell, NIST, Member of Staff, Metallurgy DivisionLeads effort to generate diffusion mobility database. Member of Thermodynamics and Kinetics Group, NIST supported.
Dr. Jianyun Shen, General Res. Inst. for Non-ferrous Metals of BeijingCollaborator in phase diagram assessments; annually visits lab (~3 mo).
Dr. Chinho Park, Yeungnam University, S. KoreaCollaborator in nanoparticle synthesis; sabbatical at UF
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Graduate Students
Barrett Hicks(B.S. Auburn, 2007)
Chris Muzzillo (B.S. Purdue, 2008)
Ranga Krishnan(M.S. U. Toledo, 2007)
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First Year Milestones
Milestones Met Pathways and rate constants for the base M-Se systems
indentified Cu2Se-Ga2Se3 pseudobinary phase diagram assessed Presence/absence of grain growth established
CRITICAL MILESTONE Evidence for 2 minute maximum absorber synthesis
time provided
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Budget Status and Potential for Expansion
• Total 3-year Budget: $760,863.00 (DOE: $599,556, Cost share: $161,911)– Spending rate was initially low (delay in start date, recruiting
students). No-cost requested (additional industry collaboration, redesign of Se chamber).
• Additional funding – Hire post doc to focus on industry interaction (modeling, HT-XRD
and characterization)– Pursue Cu2ZnSnS4 pathway analysis (recent announcement of
9.6% cell)
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FY 2011Plans
CuxSeInxSey
Mo/Glass
CuxSeCIGS
Mo/Glass
• HT-XRD experiments and data analysis of precursors • Explore bilayer precursor structures. Combinations of Cu2Se, CuSe, and CuSe2 with InSe, In2Se3, and In4Se3 will be examined.
• Industry provided base precursors: High rate precursors• Continue to work with industry to understand their process leading to increase throughput
• Development of diffusion mobility database• Assess mobility of the binary selenides using HT-XRD and other data• Complete assessment of Cu-In-Se system and evaluation of ternary reactions• Simulate observed pathways of CuInSe2 formation to verify the ternary diffusion
mobility database.
• HT-XRD experiments and data analysis of grain growth• Study the role of excess Cu on grain growth as function of Ga composition
• Assessment of available data and prediction of the metal Cu-Ga-In ternary phase diagram
• Binaries completed; equilibration studies of selected ternary compositions
Experimental results onCu-Ga-In ternary at 350°C
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• Pathways <2 min reaction time for absorber synthesis identified– Low temperature route to grain growth of CIS nanoparticles using peritectic decomposition of
CuSe2 and CuSe. Novel CIS nanoparticle synthesis process also developed. Disclosure filed and cells being fabricated.
– Rate data for bi-layer and co-deposited precursors promising.
• Milestones Met – building CIGS foundational understanding– Reaction pathways for absorber synthesis using HT-XRD
• Completed HT-XRD studies of metal-Se bilayer and co-deposited films. Ga-based reactions are much faster than In-based ones, now working on binary layers and Mo-Se interaction.
– Phase Diagrams and Thermochemistry• Completed assessment of the 6 binary phase diagrams with common solution model (sub-lattice).• Initial assessment of CGS diagram.• Pseudo binary CIS-CGS phase diagram assessed and optimized.
– Diffusion mobility database for CIGS • Diffusion mobilities assessed for Cu-In, Cu-Ga, Cu-Se and In-Se • Tested diffusion models used to treat the binary and ternary intermetallics
• Worked with industry to understand their absorber synthesis process
• Highly leveraged program– Working with 4 companies, collaborators at 2 national labs, and 2 international institutions
Summary
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Supplemental Slides
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Ga2Se3
Ga2Se3
Ga2Se3
Ga+Se
Glass
25°C60°C
Ga2Se3Formation
500°C25°C
Se
210°C
SeCrystallization
xSe ~ 0.86
xSe ~ 0.59
Ga+Se Precursor Annealing
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Glass
Ga
Se
25°C60°C
GaSe(101)
GaSe(008)
GaSe(110)
Se xSe ~ 0.80
xSe ~ 0.56
210°C
SeCrystallization
GaSe Formation
500°C25°C
Se/Ga Precursor Annealing
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