Low temperature deposited boron nitride thin films for a robust anti-reflection coating of solar cells

Polycrystalline boron nitride thin films deposited at low temperatures (<200 °C) are shown here to be well adapted for anti-reflection coating of solar cells. The analyses of the optical properties reveal a nearly constant index of refraction (∼2.8) and negligible transmission losses over the useful range of the solar spectrum. Boron nitride thin films are found to be well adapted for integration as anti-reflection coating layers in multi-junction terrestrial and space solar cells due to their spectral stability, their robust ceramic nature and a fairly wide bandgap (6.2 eV). Test fabrication of double layer MgF2/BN anti-reflection coating on GaAs and Si demonstrated minimal reflection losses (<5%) over a wide window of the solar irradiance (1.1–3 eV).