Charge photogeneration and Recombination in Ternary Organic Photovoltaic Blend PCDTBT/PC60BM/ICBA Studied by EPR Spectro
- PDF / 1,231,448 Bytes
- 8 Pages / 439.37 x 666.142 pts Page_size
- 21 Downloads / 194 Views
Applied Magnetic Resonance
ORIGINAL PAPER
Charge photogeneration and Recombination in Ternary Organic Photovoltaic Blend PCDTBT/PC60BM/ICBA Studied by EPR Spectroscopy Leonid V. Kulik1,2 · Mikhail N. Uvarov1,2 Received: 2 July 2020 / Revised: 14 August 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Using the stationary and pulsed EPR methods, the ternary composite PCDTBT and two fullerene acceptors PCDTBT/PC60BM/ICBA 1:1:1, as well as the corresponding binary composites PCDTBT/PC60BM 1:2 and PCDTBT/ICBA 1:2, were studied at a temperature of 80 K. Modeling these spectra allows us to estimate the contributions of P C60BM and ICBA to the light-induced EPR signal of the PCDTBT/ PC60BM/ICBA ternary composite as 0.7:0.3. The absence of new lines in the EPR spectrum of the ternary composite, in comparison with the corresponding binary ones, means that the mechanism of the molecular alloy of PC60BM and ICBA, as previously assumed, is not operative in this system, and the most probable scenario is the existence of two parallel heterojunctions PCDTBT/PC60BM and PCDTBT/ ICBA. This conclusion is confirmed by modeling the decay curves of the lightinduced EPR upon turning off the light, as well as the out-of-phase electron spin echo from the charge transfer state (the main intermediate of the photoelectric conversion) in these composites. It is noteworthy that in the ternary composite with the same fullerene acceptors, but with a different polymer donor (P3HT), the molecular alloy mechanism of two acceptors is realized (Angmo et al. in J Mater Chem C 3: 5541–5548, 2015). It is likely that the polymer donor has a decisive influence on the morphology and electron-transport properties of such ternary composites. It should be noted that the methods of light-induced EPR and out-of-phase ESE were used for the first time to study ternary donor–acceptor composites.
* Leonid V. Kulik [email protected] 1
Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Institutskaya Str. 3, 630090 Novosibirsk, Russia
2
Novosibirsk State University, Pirogova Str. 2, 630090 Novosibirsk, Russia
13
Vol.:(0123456789)
L. V. Kulik, M. N. Uvarov
1 Introduction Organic photovoltaics is promising and fast-developing field of solar technology. Even active layer of several hundred nanometers thickness can absorb substantial part of solar light of visible spectrum, giving an opportunity to make flexible and space-saving organic solar cells. Unlike inorganic devices, mostly silicon made, production of organic cells is expected to be cheap and environmentally friendly. Conventional architecture imposes using two-component donor–acceptor composites as active layer of a cell. Nevertheless, it limits a cell’s feasible efficiency mostly due to solar light being consumed in a rather narrow spectral band. One can use more complex architectures, like ternary junction cells, to overcome this limitation. Active medium of ternary cells consists of three different organic compounds. Some of such devices based u
Data Loading...
