Luminescence-based Imaging Techniques for Photovoltaics

NIST only participates in the February and August reviews.

Research on photovoltaics focuses on the development of new and improved device characterization methods for various cell technologies and the improvement of measurement science to reduce uncertainties associated with the power rating. Furthermore, as photovoltaic cells and modules age in the field under operation, various degradation phenomena start to impact the performance of the module. Imaging techniques that provide spatially resolved analysis of various faults and defects in large-area devices are now at the forefront of research and need to be expanded and improved. Luminescence-based imaging techniques such as hyperspectral electroluminescence and photoluminescence have proven to be powerful methods for identifying local shunts, sub-band gap defects, local voltage and absorption variations within the active layer of PV devices. Furthermore, if these measurements are calibrated and performed in an absolute way, important device-related quantities such as the external radiative efficiency can be obtained for every pixel of an image. 

Temperature dependent hyperspectral imaging work on III-V solar cells is currently being performed to identify, study and correlate PV loss mechanisms, such as non-radiative and non-band-to-band radiative recombination centers, with global device measurements. The marriage of imaging techniques with individual device measurements such as I-V curve, quantum efficiency and time resolved PL measurements allows us to elucidate a complete picture of charge transport phenomena in photovoltaic devices. Other opportunities include temperature and illumination dependent electrical measurements, time resolved luminescence measurements and improvements in image analysis methods by applying artificial intelligence and machine learning tools.

1. S. M. Chavali, J. Roller, M. Dagenais and B. H. Hamadani, Sol. Eng. Mater. Sol. Cells, 236, 111543 (2022).

2. B. H. Hamadani, Appl. Phys. Lett., 117, 043904 (2020)

Photovoltaics; Hyperspectral; Electroluminescence; Photoluminescence; Imaging; Device physics, External radiative efficiency, Solar cells

Citizenship:  Open to U.S. citizens