Ternary organic solar cells with 16.88% efficiency enabled by a twisted perylene diimide derivative to enhance the open-circuit voltage

In terms of high-efficiency PM6 : Y6 binary systems, there is still room to narrow the lowest unoccupied molecular orbital (LUMO) level offset (0.36 eV) between PM6 and Y6 to further mitigate energy loss through introducing a second acceptor in the construction of ternary organic solar cells (OSCs)....

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2021-03, Vol.9 (11), p.3826-3834
Main Authors: Ni, Ming-Yang, Leng, Shi-Feng, Liu, Heng, Yang, Yan-Kang, Li, Qian-Hui, Sheng, Chun-Qi, Lu, Xinhui, Liu, Feng, Wan, Jun-Hua
Format: Article
Language:English
Subjects:
Absorption
Alignment
Binary systems
Circuits
Construction standards
Diimide
Efficiency
Emission spectra
Energy dissipation
Energy levels
Molecular orbitals
NMR
Nuclear magnetic resonance
Open circuit voltage
Photovoltaic cells
Short circuit currents
Solar cells
Ternary systems
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Summary:In terms of high-efficiency PM6 : Y6 binary systems, there is still room to narrow the lowest unoccupied molecular orbital (LUMO) level offset (0.36 eV) between PM6 and Y6 to further mitigate energy loss through introducing a second acceptor in the construction of ternary organic solar cells (OSCs). In this study, we designed and synthesized a new slightly twisted perylene diimide (PDI)-tetramer with a large, planar coronene unit as the core, Cor-T-PDI , which has four quasi molecular orbitals that have little energy difference between them. Although the pairing of Cor-T-PDI with PM6 gives a fairly low photovoltaic performance, interestingly, when Cor-T-PDI is used as a second acceptor, an obvious increase in open-circuit voltage ( V oc ) was achieved for a PM6 : Y6 base ternary system due to the creation of a cascade energy level alignment by Cor-T-PDI . After tuning the PM6  :  Y6  :  Cor-T-PDI ratio to 1 : 1.0 : 0.1, the V oc value was significantly increased to 0.854 V without sacrificing the short-circuit current density ( J sc ) and fill factor (FF), resulting in a high PCE of 16.88% with a low energy loss (0.47 eV), which are among the best values for single-junction OSCs. This preliminary study shows that for a binary system with a high J sc value but low or moderate V oc values, such as the PM6:Y6 blend, producing a cascade energy level alignment is a more efficient strategy to enhance the PCE by introducing a third component with an appropriate structure. It is believed that lowering the highest unoccupied molecular orbital level of this PDI derivative to fall between that of Y6 and PM6 or tailoring the absorption to achieve a complementary absorption profile with that of the PM6:Y6 blend will further improve the efficiency. A coronene-cored perylene diimide twisted tetramer was developed as an acceptor additive to increase the V oc values of PM6 : Y6 blend-based OSCs.
ISSN:2050-7526
2050-7534
DOI:10.1039/d0tc05691j