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Organic tandem solar cells: How impedance analyses can improve the quality of external quantum efficiency measurements
Author(s) -
Bahro Daniel,
Wilck Manfred,
Mertens Adrian,
Ebenhoch Bernd,
Hauff Elizabeth,
Colsmann Alexander
Publication year - 2018
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3015
Subject(s) - tandem , quantum efficiency , optoelectronics , materials science , energy conversion efficiency , voltage , physics , composite material , quantum mechanics
Tandem architectures are one of the most promising concepts towards superior power conversion efficiencies of organic solar cells. An accurate determination of the power conversion efficiency requires correction of the spectral mismatch and thus relies on accurate external quantum efficiency (EQE) spectra. Due to the series connection of 2 subcells in the tandem architecture, the EQE of the tandem solar cell reproduces the EQE of one subcell if an appropriate bias light is chosen to selectively illuminate and hence forward bias the other subcell. The resulting internal voltage drop is then compensated by applying an external voltage to the tandem solar cell. In this work, we use impedance spectroscopy to accurately predict the minimum bias light intensity and the external voltage to enable accurate EQE measurements on both subcells. We exemplify this procedure on organic tandem solar cells comprising spectrally complementary absorbers and suggest an extended protocol for future measurements of the EQE.