Solar panels have become more efficient and reliable: what was invented in Finland

Thanks to the new encapsulation technology, solar cells worked stably at temperatures of -17 C and even after being submerged in water.

Scientists from Finland have developed a new method for creating perovskite solar cells, thanks to which the energy conversion efficiency has increased by 8%. This is reported by PV Magazine

A team from Aalto University and the University of Tampere in Finland has demonstrated a one-step encapsulation method for perovskite solar cells that provides protection against degradation caused by oxygen and moisture. The prototype was compared to a control device made using the old technology and found an improvement in efficiency. The new cells also successfully passed several stability tests.

The Finnish team used a one-step method to create polydimethylsiloxane-encapsulated perovskite solar cells that simultaneously provide anti-glare light management and protection against degradation caused by oxygen and moisture. In field tests, the cells did not degrade after being left undisturbed for 24 hours at -17 C and a maximum average wind speed of 7 m/s.

The device's energy conversion efficiency increased from 14.1% to 15.6%, which the team said was a relative improvement of 8% over reference devices. The researchers say their flexible encapsulation technology is suitable for both rigid and flexible solar cells in a wide range of applications.

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“Given that perovskite solar cells often face optical losses and suffer from instability, our research shows that simultaneous encapsulation and patterning on the front surface of solar cells can solve both problems. This form of encapsulation is versatile because it can contain different designs, providing significant flexibility and adaptability,” — said the first author Seyede Maryam Mousavi.

The research team stated that the “ideal” PSC encapsulation should address both optical loss and instability issues. Furthermore, it should be a material that does not require high-temperature processing, ultraviolet (UV) curing, or overly complex methods.

The team conducted stability tests based on the ISOS protocol. Testing the encapsulant's ability to mitigate degradation caused by oxygen and moisture in standard light-dark cycling tests showed that 80% of the initial performance was retained for the encapsulated devices after 360 h. In addition, the encapsulated devices maintained their original performance after testing at 90% relative humidity and immersion in water.

The company chose a material called polydimethylsiloxane (PDMS) to cover the entire surface and sides of the perovskite solar cells. Their frontal surface was processed using the soft lithography technique to reduce reflection and increase haze. Encapsulation was performed by immersing the elements in a PDMS mixture with a volume ratio of monomer to hardener of 5:1. The soft lithography method was based on research on the surface of a replica of a leek leaf, which showed promising optical and self-cleaning properties.

The photoelectric cells were fabricated by spin-coating and based on a tricationic mixed halide perovskite known as FAMAC, respectively to the protocol established in earlier studies. Then they were placed between a special glass on the side of the gold electrode and a negative anti-reflection mold on the opposite side of the substrates, and the edges of the substrate were covered with 0.5 ml of PDMS.