Hole Transport in Low-Donor-Content Organic Solar Cells

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)

Interna författare/redaktörer

Publikationens författare: Spoltore D, Hofacker A, Benduhn J, Ullbrich S, Nyman M, Zeika O, Schellhammer S, Fan YL, Ramirez I, Barlow S, Rieder M, Marder SR, Ortrnann F, Vandewal K
Publiceringsår: 2018
Tidskrift: Journal of Physical Chemistry Letters
Tidskriftsakronym: J PHYS CHEM LETT
Volym: 9
Artikelns första sida, sidnummer: 5496
Artikelns sista sida, sidnummer: 5501
Antal sidor: 11
ISSN: 1948-7185


Organic solar cells with an electron donor diluted in a fullerene matrix have a reduced density of donor-fullerene contacts, resulting in decreased free-carrier recombination and increased open-circuit voltages. However, the low donor concentration prevents the formation of percolation pathways for holes. Notwithstanding, high (>75%) external quantum efficiencies can be reached, suggesting an effective hole-transport mechanism. Here, we perform a systematic study of the hole mobilities of 18 donors, diluted at similar to 6 mol % in C-60, with varying frontier energy level offsets and relaxation energies. We find that hole transport between isolated donor molecules occurs by long-range tunneling through several fullerene molecules, with the hole mobilities being correlated to the relaxation energy of the donor. The transport mechanism presented in this study is of general relevance to bulk heterojunction organic solar cells where mixed phases of fullerene containing a small fraction of a donor material or vice versa are present as well.

Senast uppdaterad 2020-25-02 vid 03:29