TY  - INPR
A1  - Stennett, Tom E.
A1  - Bissinger, Philipp
A1  - Griesbeck, Stefanie
A1  - Ullrich, Stefan
A1  - Krummenacher, Ivo
A1  - Auth, Michael
A1  - Sperlich, Andreas
A1  - Stolte, Matthias
A1  - Radacki, Krzysztof
A1  - Yao, Chang-Jiang
A1  - Würthner, Frank
A1  - Steffen, Andreas
A1  - Marder, Todd B.
A1  - Braunschweig, Holger
T1  - Near-Infrared Quadrupolar Chromophores Combining Three-Coordinate Boron-Based Superdonor and Superacceptor Units
T2  - Angewandte Chemie, International Edition
N2  - In this work, two new quadrupolar A-π-D-π-A chromophores have been prepared featuring a strongly electron- donating diborene core and strongly electron-accepting dimesitylboryl F(BMes2) and bis(2,4,6-tris(trifluoromethyl)phenyl)boryl (BMes2) end groups. Analysis of the compounds by NMR spectroscopy, X-ray crystallography, cyclic voltammetry and UV-vis-NIR absorption and emission spectroscopy indicated that the compounds possess extended conjugated π-systems spanning their B4C8 cores. The combination of exceptionally potent π-donor (diborene) and π- acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO-LUMO gaps, resulting in strong absorption in the near-IR region with maxima in THF at 840 and 1092 nm, respectively, and very high extinction coefficients of ca. 120,000 M-1cm-1. Both molecules also display weak near-IR fluorescence with small Stokes shifts.
KW  - boron
KW  - near-IR chromophores
KW  - conjugation
KW  - low-valent compounds
KW  - synthesis
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-180391
N1  - This is the pre-peer reviewed version of the following article: T. E. Stennett, P. Bissinger, S. Griesbeck, S. Ullrich, I. Krummenacher, M. Auth, A. Sperlich, M. Stolte, K. Radacki, C.-J. Yao, F. Wuerthner, A. Steffen, T. B. Marder, H. Braunschweig, Angew. Chem. Int. Ed. 2019, 58, 6449. , which has been published in final form at  https://doi.org/10.1002/anie.201900889. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - JOUR
A1  - Sperlich, Andreas
A1  - Auth, Michael
A1  - Dyakonov, Vladimir
T1  - Charge transfer in ternary solar cells employing two fullerene derivatives: where do electrons go?
BT  - Dedicated to Prof. Sariciftci on the occasion of his 60th birthday
JF  - Israel Journal of Chemistry
N2  - Earlier reports demonstrated that ternary organic solar cells (OSC) made of donor polymers (D) blended with different mixtures of fullerene acceptors (A : A) performed very similarly. This finding is surprising, as the corresponding fullerene LUMO levels are slightly different, which might result in decisive differences in the charge transfer step. We investigate ternary OSC (D : A : A) made of the donor polymer P3HT with stoichiometric mixtures of different fullerene derivatives, PC\(_{60}\)BM : PC\(_{70}\)BM and PC\(_{70}\)BM : IC\(_{60}\)BA, respectively. Using quantitative electron paramagnetic resonance (EPR) we can distinguish between positive and negative polarons, localized on the specific molecules. We found that after the initial charge transfer step, the electrons are re-distributed over two nearby acceptors in agreement with their stoichiometry and their relative LUMO energy difference. Remarkably, the measured ΔLUMO differences in fullerene mixtures are reduced by an order of magnitude compared to that of the pristine materials, i. e., below 1 meV for PC\(_{60}\)BM : PC\(_{70}\)BM and (20±5) meV for PC\(_{70}\)BM : IC\(_{60}\)BA. Furthermore, we found that this reduced ΔLUMO explains the shift in open circuit voltage for D : A : A organic solar cells. We attribute these findings to hybridization, leading to an effective fullerene LUMO. Consequently, multi-acceptor blends are indeed a viable option for photodetectors and solar cells, as they combine the best electron acceptor and light absorbing properties.
KW  - ternary organic solar cells
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257506
VL  - 62
IS  - 7-8
ER  -