Highly emissive and low refractive index layers from doped silica nanospheres for solar cell applications

► Quantum confinement of europium (Eu3+) ions in silica (SiO2) nanospheres using sol-lyophilization process resulted an efficient red-emitting nanophosphor system when excited via charge transfer states (CTS) absorption in UV (393 nm) radiation. This improvement in photoluminescence intensity is significantly high and is explained on the basis of modulation of f-f transition due to quantum confinement of rare-earth ion in a nanosize host. ► It is also evidenced that the short range crystallanity and confinement effects provided by the nanospheres increases the Eu3+ emission intensity by almost ten times at the expense of CTS. This is the first report of this kind and has been reported for the first time by our group by a simple process that suitably modulates the emission from Eu3+ doped SiO2 nanospheres. ► Coating of these modified SiO2 nanospheres resulted in low refractive index layers that are highly desirable as cover glazing for solar collectors and in solar cells for improving the photocurrent thereby increasing the efficiency of photovoltaic cells.