The NASA Glenn Research Center is researching low-cost, highly efficient chalcopyrite thin-film solar cells on lightweight polymer substrates that will ultimately lower the mass-specific power (watts/kilograms) of the cells, allowing extra payload for missions in space as well as cost reduction. In addition, thin-film cells are anticipated to have greater resistance to radiation damage in space, enabling their use in a wide range of orbits and prolonging their lifetime. The flexibility of the substrate has the added benefit of enabling roll-to-roll processing.
Current methods for depositing ternary chalcopyrite (I-III-VI2) thin-film compounds often require multisource inorganic/organometallic precursors and high-temperature (>500 °C) processes, including toxic sulfurization or selenization steps. The high-temperature requirements are incompatible with existing space-grade polymer substrates, and the use of toxic gases is not environmentally friendly. To overcome these obstacles, Glenn and the Ohio Aerospace Institute (OAI) have developed single-source precursors for the thin-film deposition of chalcopyrite materials (ref. 1). The precursors have “built-in” I-III-VI stoichiometry with desirable thermophysical properties for low-temperature deposition.
Decomposition of single-source precursor to yield chalcopyrite compounds.
Aerosol-assisted chemical vapor deposition (AACVD) can easily be adapted to use liquid precursors in the deposition of large-area thin films. Single-source precursors have enabled the AACVD of single-phase (112)-oriented copper indium sulfide (CuInS2) thin films on glass substrates at under 400 °C and have showed promising potential for polymer substrates (refs. 2 and 3).
Light current-voltage characteristics of a chalcopyrite thin-film solar cell fabricated with CuInS2 deposited by AACVD using a single-source precursor.
The entire fabrication process for the chalcopyrite photovoltaic device was established at Glenn, and the CuInS2 thin-film solar cells on glass were constructed at Glenn, Oberlin College, and the Institute of Energy Conversion at the University of Delaware (ref. 3). The light current-voltage characteristics of the solar cell showed an open-circuit voltage over 400 mV and a short-circuit current over 7 mA/cm2; that is comparable to other AACVD-made, chalcopyrite thin-film solar cells using more than one source. The single-source precursors can provide a simple novel fabrication process for multijunction solar cells composed of several chalcopyrite compounds with different bandgaps.
Find out more about this research.
Glenn contact: Dr. Aloysius F. Hepp, 216-433-3835, Aloysius.F.Hepp@nasa.gov
Ohio Aerospace Institute (OAI) contact: Dr. Michael H.-C. Jin, 216-433-3540, Michael.H.Jin@grc.nasa.gov
Authors: Dr. Michael H.-C. Jin, Dr. Kulbinder K. Banger, Jeremiah S. McNatt, Dr. John E. Dickman, and Dr. Aloysius F. Hepp
Headquarters program office: Exploration Systems
Programs/Projects: ESR&T
Last updated: July 20, 2005 10:46 AM
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