Optical properties of conductive silver-nanowire films with different nanowire lengths

Transparent electrodes made of silver nanowires (Ag NWs) exhibit a higher flexibility than conventional indium tin oxide electrodes. For this reason, Ag NWs may find applications in future flexible electronic and optoelectronic devices. However, different optoelectronic devices have different specific requirements for Ag NWs. For example, the optical transmittance haze is an important but rarely studied aspect of Ag NW films. In this study, the optical transmittance and optical scattering of long (5-50 μm, L-NWs) and short (1-20 μm, S-NWs) Ag NW films were investigated. The L-NWs exhibited better optical transmission than the S-NWs, whereas the S-NWs exhibited better light-scattering properties than the L-NWs. Our results indicate that the L-NWs are suitable for touch-screen displays, whereas the S-NWs are better suited as transparent conductive films for solar cells. We analyzed the scattering ratio of forward-scattered light to backscattered light for both the L-NWs and S-NWs and discovered that the mesh size affected the scattering ratio. For longer wavelengths, a larger mesh yielded a higher backscattering ratio, whereas a smaller mesh yielded a lower backscattering ratio. We formulated an equation for calculating the reflection haze using the total reflection (Ag NWs/glass), R and the reflection of glass, R₀. The reflection haze of the S-NWs and L-NWs exhibited different trends in the visible-near-infrared region. An omnidirectional scattering model for the Ag NWs was used to evaluate the Ag NW scattering properties. The results of this study have great significance for the evaluation of the performance of Ag NWs in optoelectronic devices.