2007 – 2019 Group Manager, National Renewable Energy Laboratory, Golden, CO• Principal Investigator for DOE-funded Cell and Module Performance Project in the National Center for Photovoltaics; Sept. 2016 – July 2019• Principal Investigator for the DOE-funded Advanced Characterization Project in the National Center for Photovoltaics; Sept. 2013 – Sept. 2016.• Principal Investigator for DOE-funded Electro-Optical Characterization Project in the National Center for Photovoltaics; Jan. 2007 – Sept. 2013.2000 – 2006 Senior Scientist II, National Renewable Energy Laboratory, Golden, CO• Developed NREL’s program in spectroscopic ellipsometry. Performed extensive R&D using in situ real time spectroscopic ellipsometry to study the growth dynamics of HWCVD amorphous and polycrystalline silicon.1995 – 2000 Senior Scientist I, National Renewable Energy Laboratory, Golden, CO• Specialized in time-resolved photoluminescence for characterization of minority carrier lifetime in a wide range of crystalline and polycrystalline semiconductors and PV devices1993 – 1995 Staff Scientist, National Renewable Energy Laboratory, Golden, CO• Specialized in time-resolved photoluminescence for characterization of minority carrier lifetime in a wide range of crystalline and polycrystalline semiconductors and PV devices1990 – 1993 Postdoctoral research associate, Solar Energy Research Institute, Golden, CO• Helped develop and set up NREL’s time-resolved photoluminescence laboratory; utilized TRPL to study hot carrier dynamics in semiconductor quantum wells