An image sensor is constructed on a substrate that is a read-out transistor array with a multilayer array of infrared photodetectors formed thereon. The infrared photodetectors include a multiplicity of layers including an infrared transparent electrode distal to the substrate, a counter electrode directly contacting the substrate, and an infrared sensitizing layer that comprises a multiplicity of nanoparticles. The layers can be inorganic or organic materials. In addition to the electrodes and sensitizing layers, the multilayer stack can include a hole-blocking layer, an electron-blocking layer, and an anti-reflective layer. The infrared sensitizing layer can be PbS or PbSe quantum dots.