Effect of Bending on the Spectrum of Backlight Transmitted Through Flexible ITO/PET Substrate

Flexible displays and electronics fascinate the researchers all around the globe due to their less thickness and light weight. ITO coated PET substrate is the most commonly used flexible substrate for fabricating organic and polymeric electronic and photonic devices for future displays and light sources. Due to the presence of residual stress and other defects, the electro-optical characterization of these substrates is essential. In this paper, we report the measurement of spectral properties of light transmitted through ITO/PET substrate. Spectral changes and modulations were observed on bending the PET substrate. Experimental results of spectral changes and modulations using the R, G, B, and W LEDs as well as broad band halogen source are reported. CIE coordinates were also reported for the change in the spectral profile. Spectral changes in presence of flexible substrate are attributed due to residual stress and due to bending the substrate leading to change in refractive index.