Morphology control for tunable optical properties of cellulose nanofibrils films

Flexible cellulose nanofibrils film substrates with high smooth surface and high transparency are attractive for next- generation flexible transparent electrical device applications. In recent years, tuning optical properties of the substrates has become more and more important for the fabrication of the transparent electronic devices. In this study, a simple depositing process with micro-scale TEMPO-oxidized wood fibers was utilized to tune top surface morphology of the cellulose nanofibrils films. The influence of the surface morphology on the optical properties was also investigated. As the upper surface roughness increased, the optical haze of the transparent films increased. The obtained films, with total transmittance ranged from 83% to 88%, exhibited relatively low haze of 3.8% to high haze of 62.3%. In addition, the lower surface of cellulose nanofibrils films has a super flat surface, which is required for applications in electronics and optoelectronics.