Visible to near-infrared down-shifting in Tm3+ doped fluoride glasses for solar cells efficiency enhancement

In this paper, down-conversion of Tm³⁺ doped fluoride ZLAG glasses with composition of 70.2ZrF₄-(23.4-x)LaF₃-0.6AlF₃-5.8GaF₃-xTmF₃ (x = 0.25, 0.5, 0.75, 1, 2, 3 and 5 mol%) were tested as encapsulation materials for solar cells. The current density - voltage (J-V) characterizations were performed under solar simulator irradiation. The influence of Tm³⁺ concentration on the mono crystalline silicon solar cells performances was investigated. A slight increase of the solar cell efficiency was observed in the case of fluoride ZLAG for Tm³⁺ doping concentrations up to 1 mol% Tm³⁺. Further increase of the Tm³⁺ concentration leads to a decrease of solar cell conversion efficiency as a result of concentration quenching.