All-printed full-color pixel organic photodiode array with a single active layer

Abstract

Abstract A new fabrication method to realize fully-printed organic photodiode (OPD) arrays capable of RGB light separation is presented. From the photocurrents generated by each pixel type under the light from RGB LEDs, we demonstrate that this “White”, “Yellow” and “Red” array can successfully detect and reconstruct colors in the RGB system, with an average accuracy of 98.5%. A flexible broadband OPD array is printed on PEN substrate by blade-coating PEDOT:PSS, a polyethylenimine cathode interlayer and the photo-active layer, and screen-printing on top a patterned PEDOT:PSS anode. The OPD array achieves an average EQE of ∼37% at −4 V bias over the whole visible spectrum, 5 orders of magnitude of linear dynamic range (LDR), a 0.5 nA/cm2 dark current, and maintains these performances in ambient conditions for more than 30 h. Pixels detecting “White”, “Yellow” and “Red” are fabricated by spray-coating two color filters. The substrate is used as a separator between the filters and OPD array. This physical separation allows solution processing of the filters regardless of their electrical properties or of the compatibility of their solvents with the OPD, thus broadening the choice of filter materials while offering a simple fabrication process. The combination of broadband OPD and broadband filters used in this configuration can significantly simplify the fabrication of spectrally-selective photosensors and full-color imagers.