Dye and polymer based light sensor for tag integration

In this work we present a light sensor for tag integration based on the principle of a dye sensitized solar cell, using a flexible substrate and a polymer electrolyte. These features make an integration of the light sensor into current smart label fabrication processes possible. A printable light sensor combined with novel conductive polymers could solve reliability issues resulting from bonding processes. The components of the light sensor were chosen in a way to enable screen print production. The dye Ruthenium 535-bis-TBA has been used as active dye and Iodolyte AN-50 by Solaronix and PEDOT/PSS by H.C. Starck have been used as liquid and polymer electrolyte respectively. In order to prepare the liquid electrolyte for tag integration it has been gelatinized by addition of silica gel. Depending on the amount of silica gel different stiffness levels have been achieved. The functional layers have been deposited first on glass substrate and then on KAPTON foil by Du Pont. The polymer has been used as flexible substrate. Special care has been taken regarding the preparation of the transparent electrode. The transparent conductive oxide (TCO) indium tin oxide (ITO), which has been used as transparent electrode, has to be cured at elevated temperatures on the polymer substrate. A complete process flow for an integrated light sensor is being described in this work.