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Influence of Alq 3 and/or Al 2 O 3 layers at the C 60 /aluminum interface on the I – V characteristics of CuPc/C 60 ‐based solar cells
Author(s) -
Morsli M.,
Berredjem Y.,
Drici A.,
Kouskoussa B.,
Boulmokh A.,
Bernède J. C.
Publication year - 2008
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200723680
Subject(s) - copper phthalocyanine , ohmic contact , aluminium , fullerene , exciton , materials science , thin film , copper , space charge , analytical chemistry (journal) , optoelectronics , chemistry , condensed matter physics , nanotechnology , layer (electronics) , composite material , electron , organic chemistry , metallurgy , physics , quantum mechanics
The electrical properties of organic solar cells based on the couple copper phthalocyanine/fullerene (CuPc/C 60 ) have been studied as a function of the interface fullerene/aluminum (C 60 /Al). It is shown that, in the case of direct contact, the cells properties depend on the ageing of the cells. Indeed, when the cell is in contact for 5 min with air before encapsulation, i.e. when a thin natural alumina (Al 2 O 3 ) layer is present between the C 60 and Al there is an increase of the open‐circuit voltage, which is attributed to an increase of the shunt resistance. When a tris(8‐hydroxyquinoline) (Alq 3 ) thin film is introduced between the C 60 and the Al, ageing of the devices, that is to say the contact or not for 5 min with air before encapsulation, does not strongly modify the cells properties. The presence of such exciton blocking film improves the cell performance. It is shown that in the presence of Alq 3 the forward bias adhered qualitatively to expectations for p–n junctions at the CuPc/C 60 interface. Without this blocking exciton film, the analysis of the variation of the current with the forward bias shows that it fails to behave like a p–n junction. In this case it is shown that the current flow can be seen as nearly ohmic at low fields and close to space‐charge limited at higher fields. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)