@article{He:2020:10.1039/d0tc04110f,
author = {He, Q and Eisner, FD and Pearce, D and Hodsden, T and Rezasoltani, E and Medranda, D and Fei, Z and Nelson, J and Heeney, M},
doi = {10.1039/d0tc04110f},
journal = {Journal of Materials Chemistry C},
pages = {17237--17244},
title = {Ring fusion in tetrathienylethene cored perylene diimide tetramers affords acceptors with strong and broad absorption in the near-UV to visible region},
url = {http://dx.doi.org/10.1039/d0tc04110f},
volume = {8},
year = {2020}
}

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TY  - JOUR
AB  - In this work, we designed and synthesized two novel perylene diimide (PDI) tetramers based on a tetrathienylethene core, named TTE-PDI4 and FTTE-PDI4, and investigated their application as non-fullerene acceptors for organic photovoltaics. The free rotation of PDIs and adjacent thiophene units renders TTE-PDI4 with a highly twisted molecular geometry. The ring fusion of TTE-PDI4 yields FTTE-PDI4, a more rigid molecule with increased intramolecular stacking. Interestingly, TTE-PDI4 and FTTE-PDI4 possess similar energy levels but very different UV-Vis absorptions, with the latter showing strong broad-band absorption with multiple sharp peaks in the 300–600 nm region. Through time-dependent density functional theory (TD-DFT) calculations, we show that this broad absorption spectrum in FTTE-PDI4 arises from the combination of multiple bright transitions in the visible region with a strong vibronic progression, tentatively assigned to the dominant C[double bond, length as m-dash]C stretching mode. TTE-PDI4, despite having a lower energy absorption onset, shows weaker absorption at long wavelengths. Due to its higher absorption as well as its increased rigidity, FTTE-PDI4 shows a higher photocurrent and hence a higher power conversion efficiency (PCE), of 6.6%, when blended with the polymer donor PFBDB-T than TTE-PDI4 based blends (PCE of 3.8%). The greater rigidity of FTTE-PDI4 is likely to contribute to the good fill factor of the blend devices. Potential for further improvement through reducing voltage losses is identified.
AU  - He,Q
AU  - Eisner,FD
AU  - Pearce,D
AU  - Hodsden,T
AU  - Rezasoltani,E
AU  - Medranda,D
AU  - Fei,Z
AU  - Nelson,J
AU  - Heeney,M
DO  - 10.1039/d0tc04110f
EP  - 17244
PY  - 2020///
SN  - 2050-7526
SP  - 17237
TI  - Ring fusion in tetrathienylethene cored perylene diimide tetramers affords acceptors with strong and broad absorption in the near-UV to visible region
T2  - Journal of Materials Chemistry C
UR  - http://dx.doi.org/10.1039/d0tc04110f
UR  - https://pubs.rsc.org/en/content/articlelanding/2020/TC/D0TC04110F#!divAbstract
UR  - http://hdl.handle.net/10044/1/84763
VL  - 8
ER  - 

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