2021 Advanced Materials (IF 30.849): How to Use Cost-Effective Strategy to Improve the Properties of Nonfullerene Organic Solar Cells
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In October 2021, Advanced Materials (IF 30.849) published a study. Because organic solar cells (OSC) have the advantages of color tunability, semitransparency and light weight, they have great potential in wearable/portable electronic products and modern buildings. A high-performance OSC composed of a conjugated polymer donors and nonfullerene small molecule acceptors (NF-SMAs) can quickly improve efficiency. Nevertheless, many polymer donors have the characteristics of high stiffness and with very brittle small molecule receptors, which limits their application in wearable devices. In order to improve the stretchability and reduce the stiffness of the NF-SMA polymer, the authors succeeded in adding a low-cost commercial thermoplastic elastomer “polystyrene-block-poly(ethylene-ran-butene)-block-polystyrene (SEBS)” to maintain high efficiency. Using PM6:N3 as the main system of interest, the mechanical properties, surface morphology, bulk phase structure, molecular order and photovoltaic performance of the blend films with varied SEBS contents were thoroughly characterized.
(a) Molecular structures of the polymer donor and fullerene-free small molecular acceptor materials used in this work.(b) 2D GIWAXS pattern of the neat thermoplastic elastomer film. Inset is the chemical structure of the thermoplastic elastomer SEBS.
Enlitech’s Solar Simulator and QE-R Quantum Efficiency Measurement system were used in this study to assist in the measurement of experimental data. It was found that in the obtained PM6:N3:SEBS blend film, the COS gradually increased with the increase of SEBS weight content. Under the stretch of a certain strain (30%) stretching, its modulus and crack size monotonically decreased. In addition, adding a small weight amount of SEBS can improve the out-of-plane π-π stacking and face-on fraction, and at the same time has little effect on the PM6/N3 phase separation. This mechanical performance improvement strategy has shown excellent applicability in some other OSC blend systems, e.g., PBQx-TF:eC9-2Cl and PBDB-T:ITIC. More importantly, the elastic modulus of such complex ternary blends can be well predicted by the mechanical model. Therefore, adding thermoplastic elastomers is a widely applicable and cost-effective strategy that can improve the mechanical properties of nonfullerene OSCs and beyond. This emerging polymer elastomers with distinct chemical structures are also worthy of further exploration.
The quantum efficiency measurement system is used for EQE (external quantum efficiency) spectral analysis of perovskite solar cells. It also provides a comparison of Jsc (short-circuit current density) for the short-circuit current of solar cells under sunlight to prove the experimental results. At the same time, Enlitech’s solar simulator and KA-6000 software provide a short-term monitoring of time changes to prove the stability of the perovskite solar cell!
(b) elastic modulus of the PM6:N3:SEBS ternary blend films measured by FOE method.
(a) Conventional configuration of the ternary OSCs based on PM6:N3:SEBS blends. (b) Typical current density-voltage characteristics of the ternary OSCs under the optimized conditions based on PM6:N3:SEBS blends.
Keyword: thermoplastic elastomer, organic solar cell, Solar Simulator, Quantum Efficiency, Sun Simulator, Light Simulator
Article link: https://doi.org/10.1002/adma.202106732