Researchers use a transparent spectral converter to improve perovskite solar cells

Researchers from China's Shanghai University of Engineering Science have developed a novel solar spectral converter using a GdPO₄ glass-ceramic (GC) material doped with praseodymium (Pr) and europium (Eu) ions. This technology could lead to notable boosts in performance and applicability of solar cells.

The main purpose of GdPO₄-GC:Eu³⁺/Pr³⁺ is to absorb UV photons from solar radiation and re-emit them as visible light. This is possible thanks to the efficient energy transfer that happens between the ions in the material.

When a UV photon hits a Pr³⁺ ion, it generates an excited electronic state. This accumulated energy has a high chance of being transferred to a Gd³⁺ ion, which releases some of it before transferring the rest to an Eu³⁺ ion. As a result, excited electronic states in the Eu³⁺ ion undergo a down transition to lower energy states, emitting visible light.

Several experiments confirmed that the Gd³⁺ ions act as bridges between Pr³⁺ and Eu³⁺ ions in these energy transitions. Thus, a thin transparent GdPO₄-GC:Eu³⁺/Pr³⁺ layer applied onto a solar cell not only shields it from UV photons but also feeds it additional light.

Additionally, this protective effect helps prevent photo-degradation in perovskite solar cells. Meanwhile, in both perovskite and a-SiC:H solar cells, the spectral conversion layer helps the overall system use energy from solar radiation more efficiently by making it "sensitive" to UV photons, which would otherwise be wasted.

Notably, the proposed GdPO₄-GC:Eu³⁺/Pr³⁺ material is straightforward to synthesize via a conventional melting quenching process. Moreover, since the material is also remarkably stable, it appears promising as a protective layer for space-borne PCs, such as those used in space stations.

More studies will be needed to further improve the efficiency of solar cells using doped GC materials as spectral converters. The researchers note that future work could focus on improving cost-effectiveness by adjusting doping concentrations and optimizing the thickness of the protective layer.