Effects of thickness on photoelectric properties and perovskite solar cells application of transparent conductive F and Al co-doped ZnO films

Abstract

ZnO films with excellent photoelectric properties have been realized in this study through low-concentration F-and-Al co-doping, conducted with radio-frequency magnetron sputtering. It has been demonstrated that the valence state of Al gradually changes from the incomplete oxidation state to the oxidation state, though the chemical valence states of F, O, and Zn are stable. The as-prepared films possess good performance with a mobility of ∼41.89 cm2/Vs, resistivity of ∼3.50 × 10−4 Ω cm, and an average transmittance over 90% in the range of 400–1200 nm. Moreover, the crystallinity of the films and effect of Al doping were further improved through post annealing. Consequently, the improved film mobility, carrier concentration, resistivity, and sheet resistance were, respectively, measured as 53.97 cm2/Vs, 5.18 × 1020 cm−3, 2.23 × 10−4 Ω cm, and 2.73 Ω/□. These films are, therefore, superior to the commercial F-doped SnO2 (FTO) and comparable to the Sn-doped In2O3 (ITO) films. High-performance perovskite with a conversion efficiency as high as 16.24% was achieved when the abovementioned optimized film was used as the front electrode. The reference perovskite solar cells that had commercial ITO and FTO as their front electrodes showed lower efficiency of 15.92% and 12.45%, respectively.