Raising the efficiency of polycrystalline cells with new luminescent EVA film

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from pv magazine global

Researchers at China’s Hebei University of Technology have developed a luminescent ethylene-vinyl acetate (EVA) copolymer film that is said to have the potential to raise the efficiency of conventional polycrystalline solar cells by around 0.50%.

The scientists confirmed that the pure film has a high thermal stability, which was demonstrated under a light-soaking test for 500 hours, with no luminescence degradation observed.

The EVA film is based on Europium3+, which is a monoatomic trication, and elemental europium able to convert UV light into strong visible light, as a down-shift material. Each Europium3+ atom is linked to four ligands, which also carry favorable light-harvesting abilities.

Efficiency increase by 0.51%

The new copolymer film, described by the formula Eu(ND)4CTAC/EVA, was used for the coating of large area polycrystalline silicon solar cells with an active area of 110 cm².

“A series of luminescent films with varying complex concentrations have been compared and studied in photovoltaic characterization,” the research team wrote. “The results show that in the best case, the conversion efficiency of poly-crystalline silicon solar cells increases from 15.06% to 15.57% by using the luminescent film.”

High photostability

The scientists further explained that the new luminescent film also showed excellent photostability during the experiment. According to their findings, the device maintained its luminescence intensity unchanged even under continuous UV radiation at 30°C for 500 hours. “The realization of employing stable Eu(ND)4CTAC/EVA film as a medium to enhance the PCE of Si-based solar cells demonstrated here makes it attractive for [the] photovoltaic industry,” they also affirmed.

The results of the research are presented in the paper Photovoltaic efficiency enhancement of polycrystalline silicon solar cells by a highly stable luminescent film, published in Science China Materials.