TY  - JOUR
A1  - Nikolis, Vasileios C.
A1  - Mischok, Andreas
A1  - Siegmund, Bernhard
A1  - Kublitski, Jonas
A1  - Jia, Xiangkun
A1  - Benduhn, Johannes
A1  - Hörmann, Ulrich
A1  - Neher, Dieter
A1  - Gather, Malte C.
A1  - Spoltore, Donato
A1  - Vandewal, Koen
T1  - Strong light-matter coupling for reduced photon energy losses in organic photovoltaics
JF  - Nature Communications
N2  - Strong light-matter coupling can re-arrange the exciton energies in organic semiconductors. Here, we exploit strong coupling by embedding a fullerene-free organic solar cell (OSC) photo-active layer into an optical microcavity, leading to the formation of polariton peaks and a red-shift of the optical gap. At the same time, the open-circuit voltage of the device remains unaffected. This leads to reduced photon energy losses for the low-energy polaritons and a steepening of the absorption edge. While strong coupling reduces the optical gap, the energy of the charge-transfer state is not affected for large driving force donor-acceptor systems. Interestingly, this implies that strong coupling can be exploited in OSCs to reduce the driving force for electron transfer, without chemical or microstructural modifications of the photoactive layer. Our work demonstrates that the processes determining voltage losses in OSCs can now be tuned, and reduced to unprecedented values, simply by manipulating the device architecture.
Y1  - 2019
U6  - https://doi.org/10.1038/s41467-019-11717-5
SN  - 2041-1723
VL  - 10
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Ullbrich, Sascha
A1  - Benduhn, Johannes
A1  - Jia, Xiangkun
A1  - Nikolis, Vasileios C.
A1  - Tvingstedt, Kristofer
A1  - Piersimoni, Fortunato
A1  - Roland, Steffen
A1  - Liu, Yuan
A1  - Wu, Jinhan
A1  - Fischer, Axel
A1  - Neher, Dieter
A1  - Reineke, Sebastian
A1  - Spoltore, Donato
A1  - Vandewal, Koen
T1  - Emissive and charge-generating donor-acceptor interfaces for organic optoelectronics with low voltage losses
JF  - Nature materials
N2  - Intermolecular charge-transfer states at the interface between electron donating (D) and accepting (A) materials are crucial for the operation of organic solar cells but can also be exploited for organic light-emitting diodes(1,2). Non-radiative charge-transfer state decay is dominant in state-of-the-art D-A-based organic solar cells and is responsible for large voltage losses and relatively low power-conversion efficiencies as well as electroluminescence external quantum yields in the 0.01-0.0001% range(3,4). In contrast, the electroluminescence external quantum yield reaches up to 16% in D-A-based organic light-emitting diodes(5-7). Here, we show that proper control of charge-transfer state properties allows simultaneous occurrence of a high photovoltaic and emission quantum yield within a single, visible-light-emitting D-A system. This leads to ultralow-emission turn-on voltages as well as significantly reduced voltage losses upon solar illumination. These results unify the description of the electro-optical properties of charge-transfer states in organic optoelectronic devices and foster the use of organic D-A blends in energy conversion applications involving visible and ultraviolet photons(8-11).
KW  - Electronics, photonics and device physics
KW  - Optoelectronic devices and components
KW  - Photonic devices
KW  - Solar energy and photovoltaic technology
Y1  - 2019
U6  - https://doi.org/10.1038/s41563-019-0324-5
SN  - 1476-1122
SN  - 1476-4660
VL  - 18
IS  - 5
SP  - 459
EP  - 464
PB  - Nature Publ. Group
CY  - London
ER  -