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Radiative Recombination in Bulk‐Heterojunction Solar Cells
Author(s) -
Hackl Florian,
Fromherz Thomas,
Scharber Markus C.
Publication year - 2022
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.202100134
Subject(s) - chemistry , heterojunction , photovoltaic system , polymer solar cell , solar cell , band gap , optoelectronics , perovskite (structure) , charge (physics) , open circuit voltage , radiative transfer , charge carrier , recombination , limiting , theory of solar cells , chemical physics , voltage , optics , physics , crystallography , mechanical engineering , ecology , quantum mechanics , biology , engineering , biochemistry , gene
We have studied the time‐dependent charge transfer emission in a photovoltaic device made of a blend of poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclo‐penta[2,1‐b;3,4‐b’]‐dithiophene)‐alt‐4,7‐(2,1,3 benzothiadiazole)] and [6,6]‐phenyl C 61 ‐butyric acid methyl ester, a system showing a low band‐gap suitable as absorber for bulk‐heterojunction solar cells. We find a short‐lived component (∼1 ns) and no evidence of a long‐lived emission (μs) expected if photo‐generated free charge carriers would recombine radiatively via the charge transfer state. Our results explain, why the open circuit voltage loss in the investigated solar cell is much larger compared to GaAs‐based or perovskite solar cells and highlight one of the key processes limiting the performance of bulk‐heterojunction solar cells.