An innovative family of hydrogenated amorphous silicon (a-Si: H) multicolor p-i-n photo sensors, sensitive in the VIS and the near UV spectrum, is presented. Typical values of the quantum efficiency at 350 nm and 580 nm are 5.4% and 54.7%, respectively, with -0.4 V and -12 V bias. Electro-optical studies were performed to explore the effect of combining linearly graded a-SiGe:H/mu c-SiGeC:H layers with linearly graded a-SiC:H-layers. The devices presented additionally contain a buried a-Si: H region. Low-reflective aluminum doped zinc oxide (ZnO:Al) back contacts improve the spectral color separation. mu tau-products and absorption coefficients of graded absorbers were determined. Discrete absorbers were substituted by a linear graded a-SiC: H absorption zone in the top structure, an interior a-Si: H region and a graded a-SiGe:H/a-SiC:H alloy combination. In this paper we demonstrate a reduction of interference fringes and operation at low bias voltages, combined with a highly precise adjustment of the spectral sensitivity, even in the near UV-spectrum. The device dynamic range exceeds 50 dB at 1000 lx white-light illumination. As the deposited upper layers adopt the roughness of mu c-SiGeC:H clusters in the rear absorber, we present an in-situ structured front contact without etching ZnO:Al. (C) 2012 Elsevier B.V. All rights reserved.