TY  - JOUR
A1  - Odziomek, Mateusz
A1  - Giusto, Paolo
A1  - Kossmann, Janina
A1  - Tarakina, Nadezda
A1  - Heske, Julian
A1  - Rivadeneira, Salvador M.
A1  - Keil, Waldemar
A1  - Schmidt, Claudia
A1  - Mazzanti, Stefano
A1  - Savateev, Oleksandr
A1  - Perdigon-Toro, Lorena
A1  - Neher, Dieter
A1  - Kühne, Thomas D.
A1  - Antonietti, Markus
A1  - Lopez-Salas, Nieves
T1  - "Red Carbon": a rediscovered covalent crystalline semiconductor
JF  - Advanced materials
N2  - Carbon suboxide (C3O2) is a unique molecule able to polymerize spontaneously into highly conjugated light-absorbing structures at temperatures as low as 0 degrees C. Despite obvious advantages, little is known about the nature and the functional properties of this carbonaceous material. In this work, the aim is to bring "red carbon," a forgotten polymeric semiconductor, back to the community's attention. 
A solution polymerization process is adapted to simplify the synthesis and control the structure. 
This allows one to obtain this crystalline covalent material at low temperatures. Both spectroscopic and elemental analyses support the chemical structure represented as conjugated ladder polypyrone ribbons. 
Density functional theory calculations suggest a crystalline structure of AB stacks of polypyrone ribbons and identify the material as a direct bandgap semiconductor with a medium bandgap that is further confirmed by optical analysis. 
The material shows promising photocatalytic performance using blue light. 
Moreover, the simple condensation-aromatization route described here allows the straightforward fabrication of conjugated ladder polymers and can be inspiring for the synthesis of carbonaceous materials at low temperatures in general.
KW  - carbon suboxide
KW  - carbonaceous materials
KW  - conjugated ladder polymers
KW  - covalent materials
KW  - photocatalysts
Y1  - 2022
U6  - https://doi.org/10.1002/adma.202206405
SN  - 0935-9648
SN  - 1521-4095
VL  - 34
IS  - 40
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Neusser, David
A1  - Sun, Bowen
A1  - Tan, Wen Liang
A1  - Thomsen, Lars
A1  - Schultz, Thorsten
A1  - Perdigon-Toro, Lorena
A1  - Koch, Norbert
A1  - Shoaee, Safa
A1  - McNeill, Christopher R.
A1  - Neher, Dieter
A1  - Ludwigs, Sabine
T1  - Spectroelectrochemically determined energy levels of PM6:Y6 blends and their relevance to solar cell performance
JF  - Journal of materials chemistry : C, Materials for optical and electronic devices
N2  - Recent advances in organic solar cell performance have been mainly driven forward by combining high-performance p-type donor-acceptor copolymers (e.g.PM6) and non-fullerene small molecule acceptors (e.g.Y6) as bulk-heterojunction layers. A general observation in such devices is that the device performance, e.g., the open-circuit voltage, is strongly dependent on the processing solvent. While the morphology is a typically named key parameter, the energetics of donor-acceptor blends are equally important, but less straightforward to access in the active multicomponent layer. Here, we propose to use spectral onsets during electrochemical cycling in a systematic spectroelectrochemical study of blend films to access the redox behavior and the frontier orbital energy levels of the individual compounds. Our study reveals that the highest occupied molecular orbital offset (Delta E-HOMO) in PM6:Y6 blends is similar to 0.3 eV, which is comparable to the binding energy of Y6 excitons and therefore implies a nearly zero driving force for the dissociation of Y6 excitons. Switching the PM6 orientation in the blend films from face-on to edge-on in bulk has only a minor influence on the positions of the energy levels, but shows significant differences in the open circuit voltage of the device. We explain this phenomenon by the different interfacial molecular orientations, which are known to affect the non-radiative decay rate of the charge-transfer state. We compare our results to ultraviolet photoelectron spectroscopy data, which shows distinct differences in the HOMO offsets in the PM6:Y6 blend compared to neat films. This highlights the necessity to measure the energy levels of the individual compounds in device-relevant blend films.
Y1  - 2022
U6  - https://doi.org/10.1039/d2tc01918c
SN  - 2050-7526
SN  - 2050-7534
VL  - 10
IS  - 32
SP  - 11565
EP  - 11578
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -