TY  - JOUR
A1  - Köhler, Anna
A1  - Beljonne, David
T1  - The singlet-triplet exchange energy in conjugated polymers
Y1  - 2004
SN  - 1616-3028
SN  - 1616-301X
ER  - 
TY  - JOUR
A1  - Benduhn, Johannes
A1  - Piersimoni, Fortunato
A1  - Londi, Giacomo
A1  - Kirch, Anton
A1  - Widmer, Johannes
A1  - Koerner, Christian
A1  - Beljonne, David
A1  - Neher, Dieter
A1  - Spoltore, Donato
A1  - Vandewal, Koen
T1  - Impact of triplet excited states on the open-circuit voltage of organic solar cells
JF  - dvanced energy materials
N2  - The best organic solar cells (OSCs) achieve comparable peak external quantum efficiencies and fill factors as conventional photovoltaic devices. However, their voltage losses are much higher, in particular those due to nonradiative recombination. To investigate the possible role of triplet states on the donor or acceptor materials in this process, model systems comprising Zn- and Cu-phthalocyanine (Pc), as well as fluorinated versions of these donors, combined with C-60 as acceptor are studied. Fluorination allows tuning the energy level alignment between the lowest energy triplet state (T-1) and the charge-transfer (CT) state, while the replacement of Zn by Cu as the central metal in the Pcs leads to a largely enhanced spin-orbit coupling. Only in the latter case, a substantial influence of the triplet state on the nonradiative voltage losses is observed. In contrast, it is found that for a large series of typical OSC materials, the relative energy level alignment between T-1 and the CT state does not substantially affect nonradiative voltage losses.
KW  - charge-transfer states
KW  - nonradiative voltage losses
KW  - organic solar cells
KW  - triplet excited states
Y1  - 2018
U6  - https://doi.org/10.1002/aenm.201800451
SN  - 1614-6832
SN  - 1614-6840
VL  - 8
IS  - 21
PB  - Wiley-VCH
CY  - Weinheim
ER  -