Energy & Green Tech

In the stratosphere, flexible organic solar cells are being used.

Environmental monitoring, disaster relief and mitigation, agricultural and forestry monitoring, resource exploration, and communication are just a few of the many uses for near-space aircraft and fictitious high-altitude satellites in the stratosphere. For near-space vehicles and phony high-altitude satellites, solar energy is the best available source of power.

Unlike solar panels used on Earth, solar panels used in space applications need to be highly reliable in the environment of the stratosphere. This is necessary to reduce the overall weight of the power system, which in turn increases the payload and endurance of the aircraft.

In contrast to more established solar cell technologies, emerging nano-thin film solar cells, such as organic and perovskite solar cells, are very desirable for aerospace applications due to their high power-to-weight ratio and exceptional flexibility, which are a result of their ultrathin layered structure.

Although conceptual proof of the performance at satellite altitudes and in the stratosphere was achieved using high-altitude balloons or rocket flights, respectively, no research on the performance and stability of the large-area flexible organic solar cells (FOSCs) in the stratosphere environment was reported.

The in-situ performance and stability of large-area FOSCs in the 35 km stratosphere environment were investigated by researchers from the Suzhou Institute of Nano-Tech and Nano-Bionics and the Aerospace Information Research Institute, the Chinese Academy of Sciences, and the National Center for Nanoscience and Technology with a high-altitude balloon.

The 0  64 cm2 non-fullerene flexible organic solar cells were made using a solution-processed method with electrodes made of PET or AgNW that were gravure-printed. Testing was done in the lab to assess how well FOSCs performed under simulated conditions, including low-temperature performance, thermal cycling, and UV illumination.

Additionally, in-situ measurement results revealed that the FOSCs provided the highest power density of 15.26 mW/cm2 and efficiency of 11.16 percent at 35 km under the irradiation of AM0, corresponding to a power-per-weight ratio of 3.32 kW/kg. Additionally, the flexible organic solar cells maintained stability during a 3-hour flight at 35 km/h. These findings have significant implications for space solar cells and demonstrate the viability of large-area FOSCs for use in space.

The National Science Review journal publishes the findings.

More information: Zihan Xu et al, In situ performance and stability tests of large-area flexible polymer solar cells in the 35-km stratospheric environment, National Science Review (2022). DOI: 10.1093/nsr/nwac285

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