Public Abstract

DE-SC0025506: Group-V Doping of CdTe-Alloy Polycrystalline and Single Crystal Thin Films

Award Status: Active

Institution: University Of Delaware, Newark, DE
UEI: T72NHKM259N3
DUNS: 059007500

Most Recent Award Date: 09/17/2024
Number of Support Periods: 1
PM: Fitzsimmons, Timothy

Current Budget Period: 09/01/2024 - 08/31/2025
Current Project Period: 09/01/2024 - 08/31/2028
PI: Shafarman, William

Supplement Budget Period: N/A

Public Abstract

A partnership between the University of Delaware’s Institute of Energy Conversion (IEC) and Department of Materials Science and Engineering (MSE) with the National Renewable Energy Laboratory (NREL) is proposed to research group-V doping of CdTe and related alloys. The objective of the project will be to provide a scientific underpinning for controlling electronic properties in CdTe-based thin films for application to photovoltaic (PV) solar cells. This understanding is widely considered as critical for enhancement of the efficiency of solar cells and power output of CdTe PV modules to achieve the goals of DOE’s Solar Energy Technology Office (SETO) for higher performance of PV systems leading to lower cost of electricity. The proposed project further addresses goals of the EPSCoR program to enhance the university’s collaboration with DOE National Labs and develop capabilities and a pipeline to future research in Delaware. This includes training of graduate and undergraduate students, as well as early career faculty. CdTe-based solar cells are the most successful thin film photovoltaic technology at scale with respect to performance, low manufacturing cost, and minimal environmental impact. However, continued progress in increasing performance and reducing manufacturing cost are needed to remain competitive with Si wafer-based PV. Models and analysis show that the primary path to improved performance will be to reduce losses in the solar cells by controlling electronic defects that limit voltage. This project will focus on controlling the CdTe by doping with arsenic, phosphorus, or antimony – the group V elements. These atoms can replace the Te in the CdTe lattice to add free electronic carriers that are needed for higher cell voltage. The approach to this research will explore the fundamentals of this doping process using complementary thin film deposition capabilities at IEC and NREL. A vapor transport deposition process in a novel reactor at IEC will be used to investigate the doping in a system that is compatible with low-cost, high volume manufacturing approaches. The polycrystalline films made by this process will be compared to single crystal materials deposited at NREL that provide a model system for understanding the defects. Research in both systems will be guided by sample exchanges and advanced characterization at both institutions with first-principles theoretical calculations of defect formation guiding the experimental direction. The project will be carried out by the co-investigators W. Shafarman, K. Dobson, A. Janotti and X. Wang at the University of Delaware along with a team at NREL led by M. Reese and E. Colgrove. A key focus of the project will be the training of a cohort of graduate students at UD who whose doctoral research will form the heart of the project. These students will be supported for extended stays at NREL to work side-by-side with scientists there. The expected final outcomes of the project will be development of a pathway to lower cost electricity generation using CdTe thin film photovoltaics and a pipeline to future research in Delaware including expanded research coordination between the university and the national lab.

A partnership between the University of Delaware’s Institute of Energy Conversion (IEC) and Department of Materials Science and Engineering (MSE) with the National Renewable Energy Laboratory (NREL) is proposed to research group-V doping of CdTe and related alloys. The objective of the project will be to provide a scientific underpinning for controlling electronic properties in CdTe-based thin films for application to photovoltaic (PV) solar cells. This understanding is widely considered as critical for enhancement of the efficiency of solar cells and power output of CdTe PV modules to achieve the goals of DOE’s Solar Energy Technology Office (SETO) for higher performance of PV systems leading to lower cost of electricity. The proposed project further addresses goals of the EPSCoR program to enhance the university’s collaboration with DOE National Labs and develop capabilities and a pipeline to future research in Delaware. This includes training of graduate and undergraduate students, as well as early career faculty.

CdTe-based solar cells are the most successful thin film photovoltaic technology at scale with respect to performance, low manufacturing cost, and minimal environmental impact. However, continued progress in increasing performance and reducing manufacturing cost are needed to remain competitive with Si wafer-based PV. Models and analysis show that the primary path to improved performance will be to reduce losses in the solar cells by controlling electronic defects that limit voltage. This project will focus on controlling the CdTe by doping with arsenic, phosphorus, or antimony – the group V elements. These atoms can replace the Te in the CdTe lattice to add free electronic carriers that are needed for higher cell voltage. The approach to this research will explore the fundamentals of this doping process using complementary thin film deposition capabilities at IEC and NREL. A vapor transport deposition process in a novel reactor at IEC will be used to investigate the doping in a system that is compatible with low-cost, high volume manufacturing approaches. The polycrystalline films made by this process will be compared to single crystal materials deposited at NREL that provide a model system for understanding the defects. Research in both systems will be guided by sample exchanges and advanced characterization at both institutions with first-principles theoretical calculations of defect formation guiding the experimental direction.

The project will be carried out by the co-investigators W. Shafarman, K. Dobson, A. Janotti and X. Wang at the University of Delaware along with a team at NREL led by M. Reese and E. Colgrove. A key focus of the project will be the training of a cohort of graduate students at UD who whose doctoral research will form the heart of the project. These students will be supported for extended stays at NREL to work side-by-side with scientists there. The expected final outcomes of the project will be development of a pathway to lower cost electricity generation using CdTe thin film photovoltaics and a pipeline to future research in Delaware including expanded research coordination between the university and the national lab.