
South Denmark University, Denmark
By Dr. Vida Engmann, Assoc. Professor at South Denmark University, Denmark.
Organic solar cells have recently reached power conversion efficiencies of over 18%, highlighting the stability as their last remaining weak point. Their organic nature makes them strongly influenced by stresses such as oxygen, light, heat and humidity, which can be commonly found in their working environment. Incorporation of stabilizing additives (antioxidants, radical scavengers, hydroperoxide decomposers, UV absorbers) [1]-[5] in active layers of organic solar cells is an attractive approach for inhibiting degradation as it is both inexpensive and easily upscalable, and it does not introduce further complexity into the device architecture. Here we present our recent results on long-term stability improvement by biomimetic singlet oxygen quenching compounds, as well as explore the synergistic effects of such compounds on the mechanical properties. [6]-[8] Microscopic and spectroscopic characterization was used to monitor chemical degradation over time, which is discussed in terms of concentrations of radicals and singlet oxygen over the course of degradation. The reported results and methods indicate a desirable route for mitigating degradation in organic solar cells.
References:
[1] Turkovic V, Engmann S, Tsierkezos N, Hoppe H, Ritter U, Gobsch G. Long-Term Stabilization of Organic Solar Cells Using Hindered Phenols as Additives. ACS Appl. Mater. Interfaces 2014; 6, 18525-18537. dx.doi.org/10.1021/am5024989
[2] Turkovic V, Engmann S, Tsierkezos N, Hoppe H, Madsen M, Rubahn H-G, Ritter U, Gobsch G. Long-term stabilization of organic solar cells using UV absorbers. J. Phys. D: Appl. Phys. 2016; 49, 125604. dx.doi.org/10.1088/0022-3727/49/12/125604
[3] Turkovic V, Engmann S, Tsierkezos N, Hoppe H, Madsen M, Rubahn H-G, Ritter U, Gobsch G. Long-term stabilization of organic solar cells using hydroperoxide decomposers as additives. Appl. Phys. A 2016; 122:255. dx.doi.org/10.1007/s00339-016-9758-7
[4] Turkovic V, Madsen M. Inhibiting Photo-oxidative Degradation in Organic Solar Cells using Stabilizing Additives. In World Scientific Reference of Hybrid Materials, Vol. 2 Devices from Hybrid and Organic Materials, p 367-421, 2019, World Scientific Publishing. dx.doi.org/10.1142/9789813270541_0012
[5] Prete M, Aryal UK, Sandby Lissau J, Rubahn H-G, Madsen M, Turkovic V. Additive-Assisted Stabilization Against Photooxidation of Organic and Hybrid Solar Cells. In Emerging Strategies to Reduce Transmission
and Thermalization Losses in Solar Cells – Redefining the Limits of Solar Power Conversion Efficiency, p 169 – 193, 2021 (in press), Springer Nature. dx.doi.org/10.1007/978-3-030-70358-5
[6] Turkovic V, Prete M, Bregnhøj M, Inasaridze L, Volyniuk D, Obrezkov FA, Grazulevicius JV, Engmann S, Rubahn HG, Troshin PA, Ogilby PR, Madsen M. Biomimetic Approach to Inhibition of Photooxidation in Organic Solar Cells Using Beta-Carotene as an Additive. ACS Appl Mater Interfaces. 2019;11(44):41570-41579. dx.doi.org/10.1021/acsami.9b13085
[7] Bregnhøj M, Prete M, Turkovic V, Petersen AU, Nielsen MB, Madsen M, Ogilby PR. Oxygen-dependent photophysics and photochemistry of prototypical compounds for organic photovoltaics: inhibiting degradation initiated by singlet oxygen at a molecular level. Methods Appl Fluoresc. 2019;8(1):014001. dx.doi.org/10.1088/2050-6120/ab4edc
[8] Prete M, Ogliani E, Bregnhøj M, Sandby Lissau S, Dastidar S, Rubahn H-G, Engmann S, Ladegaard Skov A, Brook MA, Ogilby PR, Printz A, Turkovic V, Madsen M. Synergistic effect of carotenoid and silicone-based additives for photooxidatively stable organic solar cells with enhanced elasticity. J Mater. Chem. C 2021; (just accepted) dx.doi.org/10.1039/D1TC01544C
Biography
Vida Engmann obtained her Dr. rer. nat. in 2014 from Ilmenau University of Technology, Germany. In 2014 she joined Mads Clausen Institute at the University of Southern Denmark, where she was in 2020 appointed associate professor. Her research focuses on bioinspired approaches to stabilization of organic semiconductor thin films and energy devices. For her work on additive-assisted stabilization she received the L’Oréal-UNESCO For Women in Science national award in 2019, and International Rising Talent award in 2020. In 2020 she was awarded the Carlsberg Young Researcher Fellowship. She is a member of SDU Committee on diversity and equality and SDU Expert group on climate.