Luminescent anti-reflection coatings based on Er3+ doped forsterite for commercial silicon solar cells applications

Efficiency of solar devices is affected by several factors such as, devices surface reflection and the energy emitted in the ultraviolet and infrared regions, which are not harnessed by the cell, are among the main causes. To reduce these losses, we propose the use of rare-earth doped anti-reflection coatings. Erbium doped forsterite (Mg2SiO4:Er3+) thin films were synthesized in order to bind the anti-reflective property of forsterite films with the upconversion property of erbium ion. For the first time in literature, Mg2SiO4:Er3+ optical activity in the visible range with excitation at 1470 nm is presented. Single and double layers anti-reflective coating models, with forsterite as coating material, were simulated. The single layer model was compared to experimental data presenting elevated accordance. The coating application on silicon wafer leaded to a light absorption enhancement over 80% in the visible spectrum. The dopant influence on the films optical behavior was also studied indicating that despite the presence of erbium, the fosterite films preserved their anti-reflectivity. Moreover, the coatings were analyzed through chemical and mechanical resistance tests, indicating elevated scratch resistance (over 500 mN) and chemical stability at high humidity and corrosive environments. Mg2SiO4:Er3+ films revealed to be a promising anti-reflection coating for increasing commercial silicon-based solar cells efficiency.