Significant roughness enhancement of fluorine-doped tin oxide films with low resistivity and high transparency by using HNO₃ addition

Abstract

Current development of fluorine-doped tin oxide (FTO) films for application in solar cells is limited by tradeoffs among surface roughness related light trapping, optical transparency and electrical conductivity. Proposed methods for improving the surface roughness are usually dependent upon thickness increment or sacrificing the conductivity. In this study, we report a simple method for preparing FTO films with a flower-like grain morphology and thus a higher than ever mean roughness of 51.4-73.3 nm or mean-root-square roughness of 70.5-91 nm, by inclusion of HNO 3 additive into the deposition system. The very rough films are 200-300 nm thick and also have maintained a high transparency of 80-85% in the visible region and a low sheet resistance of 14 U , À1 and resistivity of 4.2 Â 10 À4 U cm, perhaps resulting from the effects of HNO 3 on heterogeneous nucleation and development of the (200) preferred orientation. The high roughness, combined with high transparency and low resistivity, would be beneficial to improving the light trapping of FTO films and thus the efficiency of solar cells.

Translation Effects in Fluorine Doped Tin Oxide Thin Film Properties by Atmospheric Pressure Chemical Vapour Deposition

“…The amount of F- dopant precursor is the same for this set of samples, so changes in p are assumed to be due to the change in translation rate and hence growth rate. The reduced growth rate results in decreased TC along the (200) preferred orientation and an increase in the (110) direction [22,23]. A reduction in (200) orientation has previously been linked by Wang et al [22] to lower conductivities.…”

“…Due to limited supply of polar by-product molecules in S4-S6, fewer molecules are absorbed on the F-(101) planes and result in a moderately stronger (110) peak. In a recent study, Wang and co-workers showed that different preferred orientations of FTO films (deposited by APCVD) could be achieved using different additives and then how their properties are consequently altered [23]. It was clearly demonstrated that the films with a preferred orientation along the (200) axis are highly desired as they yield improved electrical conductivities [24].…”

Spin‐Coated Bismuth Vanadate Thin Film as an Alternative Electron Transport Layer for Light‐Emitting Diode Application

“…The average RMS roughness value of the BVO3 film was lower than the BVO5 film, indicating higher surface roughness in the thin film, which may influence the optical transmittance and electrical transport properties ( Figure ). [ 45 ]…”

Cost-effective Sb-doped SnO2 films as stable and efficient alternative transparent conducting electrodes for dye-sensitized solar cells

“…[68][69][70] A rough surface predominantly enhances the reflection of incident photons back into the electrode, thereby decreasing the loss of photons and aiding the improvement in light gathering ability. 16,71 3.4. Photoluminescence measurements Fig.…”