Power generation enhanced dye-sensitized solar cells by sodium adsorption with aluminum silicate coated TiO₂ photoelectrodes

We present power-conversion-efficiency enhanced dye-sensitized solar cells by sodium adsorption with aluminum silicate coated TiO₂ photoelectrodes. Aluminum silicate in TiO₂ nanoparticles acts as an Na trap in the NaCl solution, where the trapped sodium might diffuse into the TiO₂ nanoparticles, enhancing electrical conductivity. Aluminum silicate films were fabricated by room-temperature atomic layer deposition (ALD) with ALD cycles ranging from 1 to 20. One ALD cycle corresponds to a deposition thickness from 0.10 to 0.11 nm. N719 dye and iodine electrolyte are used in the present study. In the power conversion test, the power conversion efficiency (PCE) is recorded to be 7.42% with Na adsorption and the aluminum silicate film under an AM 1.5G simulated light exposure with an intensity of 100 mW/cm². This represents an improvement from the PCE of 5.99% observed at the standard sample without either Na adsorption or the aluminum silicate film. Na adsorption by aluminum silicate enhances both short-circuit-current density and open-circuit voltage. Improvement in power conversion is attributed to enhancing the carrier conduction due to Na atoms diffusing into TiO₂ photoanodes.