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Title: Liquid-Phase Deposition of CIS Thin Layers: Final Report, February 2003--July 2005

Abstract

The goal of this project was to fabricate single-phase CIS (a-Cu-In-Se, stoichiometric composition: CuInSe2) thin films for photovoltaic applications from a liquid phase - a Cu-In-Se melt of appropriate composition. This approach of liquid-phase deposition (LPD) is based on the new phase diagram we have established for Cu-In-Se, the first complete equilibrium phase diagram of this system. The liquidus projection exhibits four composition fields in which the primary solid phase, i.e., the first solid material that forms on cooling down from an entirely liquid state, is a-CuInSe2. Remarkably, none of the four composition fields is anywhere near the stoichiometric composition (CuInSe2) of a-CuInSe2. The results demonstrate that the proposed technique is indeed capable of producing films with a particularly large grain size and a correspondingly low density of grain boundaries. To obtain films sufficiently thin for solar cell applications and with a sufficiently smooth surface, it is advantageous to employ a sliding boat mechanism. Future work on liquid-phase deposition of CIS should focus on the interaction between the melt and the substrate surface, the resulting CIS interfaces, the surface morphology of the LPD-grown films, and, of course, the electronic properties of the material.

Authors:
;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
876122
Report Number(s):
NREL/SR-520-39341
XDJ-3-30630-33; TRN: US200604%%387
DOE Contract Number:
AC36-99-GO10337
Resource Type:
Technical Report
Resource Relation:
Related Information: Work performed by Case Western Reserve University, Cleveland, Ohio
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; DEPOSITION; GRAIN BOUNDARIES; GRAIN SIZE; MORPHOLOGY; PHASE DIAGRAMS; SOLAR CELLS; SUBSTRATES; THIN FILMS; LIQUID-PHASE DEPOSITION; THIN FILM; ELECTRONIC PROPERTIES; COPPER INDIUM DISELENIDE (CIS); GRAIN BOUNDARY; SLIDING-BOAT REACTOR; Solar Energy - Photovoltaics

Citation Formats

Ernst, F., and Pirouz, P. Liquid-Phase Deposition of CIS Thin Layers: Final Report, February 2003--July 2005. United States: N. p., 2006. Web. doi:10.2172/876122.
Ernst, F., & Pirouz, P. Liquid-Phase Deposition of CIS Thin Layers: Final Report, February 2003--July 2005. United States. doi:10.2172/876122.
Ernst, F., and Pirouz, P. Wed . "Liquid-Phase Deposition of CIS Thin Layers: Final Report, February 2003--July 2005". United States. doi:10.2172/876122. https://www.osti.gov/servlets/purl/876122.
@article{osti_876122,
title = {Liquid-Phase Deposition of CIS Thin Layers: Final Report, February 2003--July 2005},
author = {Ernst, F. and Pirouz, P.},
abstractNote = {The goal of this project was to fabricate single-phase CIS (a-Cu-In-Se, stoichiometric composition: CuInSe2) thin films for photovoltaic applications from a liquid phase - a Cu-In-Se melt of appropriate composition. This approach of liquid-phase deposition (LPD) is based on the new phase diagram we have established for Cu-In-Se, the first complete equilibrium phase diagram of this system. The liquidus projection exhibits four composition fields in which the primary solid phase, i.e., the first solid material that forms on cooling down from an entirely liquid state, is a-CuInSe2. Remarkably, none of the four composition fields is anywhere near the stoichiometric composition (CuInSe2) of a-CuInSe2. The results demonstrate that the proposed technique is indeed capable of producing films with a particularly large grain size and a correspondingly low density of grain boundaries. To obtain films sufficiently thin for solar cell applications and with a sufficiently smooth surface, it is advantageous to employ a sliding boat mechanism. Future work on liquid-phase deposition of CIS should focus on the interaction between the melt and the substrate surface, the resulting CIS interfaces, the surface morphology of the LPD-grown films, and, of course, the electronic properties of the material.},
doi = {10.2172/876122},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}

Technical Report:

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  • This subcontract report describes Shell Solar Industries (SSI), formerly Siemens Solar Industries, pursuing research and development of CuInSe2-based thin-film PV technology since 1980. In the 1980s, SSI demonstrated a 14.1%-efficient 3.4-cm2 active-area cell; unencapsulated integrated modules with aperture efficiencies of 11.2% on 940 cm2 and 9.1% on 3900 cm2; and an encapsulated module with 8.7% efficiency on 3883 cm2 (verified by NREL). Since these early achievements, SSI has made outstanding progress in the initial commercialization of high-performance thin-film CIS technology. Line yield has been increased from about 60% in 2000 to about 85% in 2002. This major accomplishment supports attractivemore » cost projections for CIS. Recently, NREL confirmed a champion 12.8% aperture-area conversion efficiency for a large-area (3626 cm2) CIS module. Other than definition of the aperture area, this module is simply one module from the upper end of the production distribution for standard modules. Prerequisites for commitment to large-scale commercialization have been demonstrated at successive levels of CIS production. Remaining R&D challenges are to scale the processes to even larger areas, to reach higher production capacity, to demonstrate in-service durability over longer times, and to advance the fundamental understanding of CIS-based materials and devices with the goal of improvements for future products. SSI's thin-film CIS technology is poised to make very significant contributions to DOE/NREL/NCPV long-term goals of higher volume, lower-cost commercial products. The objective of this subcontract is to continue advancement of SSI's copper indium diselenide (CIS) technology through development and implementation of: high-throughput CIS absorber formation reactors; an XRF measurement system; a bar-code scribing system; a high-capacity ZnO monitoring system; a high-capacity continuous-light-source simulator; and integrated manufacturing infrastructure including Statistical Process Control (SPC), Manufacturing Execution Systems (MES), and intelligent processing functions.« less
  • Three-stage co-evaporation of CIGS imposes stringent limits on the parameter space if high-efficient devices are to result. Substrate temperatures during the 1st stage (as well as during the 2nd and 3rd stage), Se partial pressure, and amount of Na supplied are critical for good nucleation, proper In-Ga-selenide precursor phase, and diffusion of Cu into the precursor, as well as diffusion of Ga through the film. In addition, the degree of Cu-rich excursion impacts maximum performance and process tolerance. Enveloping the above is the basic time-temperature profile inextricably linked to the metals delivery rates. Although high-efficiency, three-stage deposited CIGS devices onmore » the R&D scale are grown at about 20-45 minutes to thicknesses of 2 to 2.5 m, the latter is not a viable approach for an economic manufacturing process. At Global Solar Energy, Inc., CIGS films are typically grown in about 6 minutes to thicknesses of less than 2 m. At the same time, the emissivity and thermal conductivity of stainless steel is vastly different from that of glass, and the reduced growth time poses restrictions on the substrate temperature ramp rates and diffusion of species (reaction kinetics). Material compatibility in the highly corrosive Se environment places limitations on the substrate heaters; i.e., substrate temperatures. Finally, one key advantage of a RTR deposition approach (compact equipment) restricts post CIGS Se exposure and cool-down rates to be vastly different than those practiced in the laboratory.« less
  • The primary objectives of this Shell Solar Industries subcontract are to address key near-term technical R&D issues for continued CIS product improvement; continue process development for increased production capacity; develop processes capable of significantly contributing to DOE 2020 PV shipment goals; advance mid- and longer-term R&D needed by industry for future product competitiveness including improving module performance, decreasing production process costs per watt produced, and improving reliability; and perform aggressive module lifetime R&D directed at developing packages that address the DOE goal for modules that will last up to 30 years while retaining 80% of initial power. These production R&Dmore » results, production volume, efficiency, high line yield, and advances in understanding are major accomplishments. The demonstrated and maintained high production yield is a major accomplishment supporting attractive cost projections for CIS. Process R&D at successive levels of CIS production has led to the continued demonstration of the prerequisites for commitment to large-scale commercialization. Process and packaging R&D during this and previous subcontracts has demonstrated the potential for further cost and performance improvements.« less
  • The objectives for this thin-film copper-indium-diselenide (CIS) solar cell project cover the following areas: Develop and characterize buffer layers for CIS-based solar cell; grow and characterize chemical-bath deposition of Znx Cd1-xS buffer layers grown on CIGS absorbers; study effects of buffer-layer processing on CIGS thin films characterized by the dual-beam optical modulation technique; grow epitaxial CuInSe2 at high temperature; study the defect structure of CGS by photoluminescence spectroscopy; investigate deep-level defects in Cu(In,Ga)Se2 solar cells by deep-level transient spectroscopy; conduct thermodynamic modeling of the isothermal 500 C section of the Cu-In-Se system using a defect model; form alpha-CuInSe2 by rapidmore » thermal processing of a stacked binary compound bilayer; investigate pulsed non-melt laser annealing on the film properties and performance of Cu(In,Ga)Se2 solar cells; and conduct device modeling and simulation of CIGS solar cells.« less
  • The overall goal of this project was to evaluate either boronated EGF or anti-EGFR monoclonal antibodies (MoAbs) as delivery agents for boron neutron capture therapy (BNCT).