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Danish researchers report that treating organic solar cells without fullerene acceptor with vitamin C provides antioxidant activity that alleviates degradative processes arising from exposure to heat, light and oxygen.
A team of researchers from the University of Southern Denmark (SDU) sought to match advances being made in the power conversion efficiencies of organic solar cells (OPVs) made with non-fullerenic acceptor materials. (NFA) with improvements in stability.
The team selected ascorbic acid, commonly known as vitamin C, and used it as a passivation layer between an electron transport layer (ETL) of zinc oxide (ZnO) and the photoactive layer of OPV NFA cells made with a stack of layers of inverted device and a semiconductor polymer (PBDB-T:IT-4F).
The scientists constructed the cell with an indium tin oxide (ITO) layer, the ZnO ETL, the vitamin C layer, the PBDB-T:IT-4F absorber, a molybdenum oxide (MoOx) carrier-selective layer ) and a silver (Ag) metal contact.
The group discovered that ascorbic acid produces a photostabilizing effect, reporting that the antioxidant activity alleviates the degradative processes derived from exposure to oxygen, light and heat. Tests, such as ultraviolet-visible absorption, impedance spectroscopy, and light-dependent voltage and current measurements, also revealed that vitamin C reduces photobleaching of NFA molecules and suppresses charge recombination, the research noted. .
Their analysis showed that, after 96 h of continuous photodegradation under 1 Sun, the encapsulated devices containing the vitamin C intermediate layer retained 62% of their original value, while the reference devices only retained 36%.
The results also demonstrated that the increase in stability did not come at the cost of efficiency. The champion device achieved a power conversion efficiency of 9.97%, an open circuit voltage of 0.69 V, a short circuit current density of 21.57 mA/cm2, and a fill factor of 66%. Reference devices without vitamin C showed an efficiency of 9.85%, an open circuit voltage of 0.68 V, a short circuit current of 21.02 mA/cm2 and a fill factor of 68%.
Vida Engmann, who leads a group at the Center for Advanced Photovoltaics and Thin Film Energy Devices (SDU CAPE), explained to pv magazine : “Our devices in this experiment were 2.8 mm2 and 6.6 mm2, but they can be scaled up. in our roll-to-roll laboratory at SDU CAPE, where we also regularly manufacture OPV modules.”
He stressed that the manufacturing method can be expanded, noting that the interfacial layer is a “cheap compound that is soluble in common solvents, so it can be used in a roll-to-roll coating process like the rest of the layers” in a cell. IPO.
Engmann sees potential for additives beyond OPV in other third-generation cell technologies, such as perovskite solar cells and dye-sensitized solar cells (DSSC). “Other technologies based on organic/hybrid semiconductors, such as DSSCs and perovskite solar cells, have similar stability problems to those of organic solar cells, so it is very likely that they can also contribute to solving the stability problems of these technologies,” he declared.
The cell was presented in the paper “ Vitamin C for Photo-Stable Non-fullerene-acceptor-Based Organic Solar Cells ,” published in ACS Applied Material Interfaces . The first author of the paper is Sambathkumar Balasubramanian of SDU CAPE. The team was made up of researchers from the SDU and the Rey Juan Carlos University.
Looking ahead, the team plans to continue researching stabilization approaches using natural antioxidants. “In the future, we will continue research in this direction,” Engmann said, referring to promising research on a new class of antioxidants. |
