Photocurrent diffusion of organic photodetector between pixels for fingerprint sensor by using interdigitated electrodes

Abstract

The organic photodetectors (OPDs) with an interdigitated electrodes (IDEs) structure are analyzed to evaluate the optical crosstalk between neighboring pixels for the organic image sensor used in the fingerprint-on-display (FOD) authentication system. The shorter exciton diffusion length of organic semiconductors in the OPD can promote the high resolution of the organic image sensor for full-display sensing applications. We demonstrated the photocurrent diffusion from the exposed area to the hidden electrodes by changing the distance to predict the minimum pixel pitch for the organic image sensor. Unexpectedly, the photocurrent diffusion was observed, even at 10 µm length, as more significant than the expected exciton diffusion length.