Project Name: Preparation and Evaluation of n-Type CdSeTe and CdTe as an Absorber in Thin-Film PV
Funding Opportunity: Solar Energy Technologies Office Fiscal Year 2018 Funding Program (SETO FY2018)
SETO Research Area: Photovoltaics
Location: Pullman, WA
SETO Award Amount: $200,000
Awardee Cost Share: $50,000
Principal Investigator: John McCloy
-- Award and cost share amounts are subject to change pending negotiations --
Dopants, which are chemicals added to a material to change its electrical properties, increase voltage and improve efficiencies in thin-film cadmium telluride (CdTe) and cadmium selenium telluride (CdSeTe) photovoltaics (PV). CdTe systems typically undergo p-type doping to increase the concentration of electron holes, which carry the most electric charge, thereby enhancing conduction. This project aims to improve CdTe performance efficiencies using n-type dopants to increase the concentration of electrons, making electrons the majority charge carrier.
The team will develop doped CdTe and CdSeTe material chemistries, incorporate dopants, and measure electron carrier density. First, they will grow single-crystal indium-doped CdTe and CdSeTe solar cell bases, or substrates, on which to deposit the thin-film PV layers. They will deposit the layers using the Bridgman method, a heating and cooling technique that enables single-crystal formation from polycrystalline seed materials. Then the team will use thermoelectric effect spectroscopy, a technique used to measure a material's electric potential when that material is heated to a higher temperature, to characterize the films, confirm the presence of n-type carriers, and establish a feedback loop to improve the doping process. They will also deposit and characterize chlorine- and indium-doped films and examine the carrier density.
Results of this work will help researchers evaluate the effectiveness of n-type doping of CdTe for increased performance efficiency. This project will improve understanding of how dopants can manipulate the electrical properties of CdTe materials, thereby widening the choice of materials that can potentially be used in PV.