Subbandgap absorption spectroscopy of thin film photovoltaic materials

0480289 - FZÚ 2018 RIV DE eng A - Abstract
Holovský, Jakub - Stückelberger, M. - Finsterle, T. - Purkrt, Adam - Musálek, L. - Benda, V. - Bertoni, M. - Haug, F.J.
Subbandgap absorption spectroscopy of thin film photovoltaic materials.
Proceedings of the 32nd European Photovoltaic Energy Conference and Exhibition. Munich: WIP, 2016. s. 1-1.
[European Photovoltaic Solar Energy Conference and Exhibition /32./. 20.06.2016-24.06.2016, Munich]
R&D Projects: GA MŠMT(CZ) LD14011
Grant - others:AV ČR(CZ) KONNECT-007
Program: Bilaterální spolupráce
Institutional support: RVO:68378271
Keywords : amorphous silicon * defect density * solar cells * photocurrent spectroscopy
OECD category: Nano-materials (production and properties)

Recent advance in the hydrogenated amorphous silicon technology and the Fourier-transform Photocurrent Spectroscopy are reviewed, including the problem of parasitic absorptance due to the surface states. A new practice of the absolute scaling of the subbandgap photocurrent signal measured on solar cells is proposed, allowing absolute determination of bulk defect density in ppm. This approach is verified by ray tracing optical simulations. In order to give practical interpretation of defect concentration in terms of device performance, a series of hydrogenated amorphous silicon solar cells of different thickness was analyzed at different states of light soaking degradation. A map of maximum attainable voltage for given bandgap and combination of thickness and defect density is presented. An interesting fundamental rule is observed: the slope of the dependence of the voltage on the logarithm of the defect density corresponds to the Urbach energy.

Permanent Link: http://hdl.handle.net/11104/0276127