A monolithic tandem electrochromic device, comprising: a central transparent conductor ion blocking layer that contains a flexible transparent film coated with central transparent conductor layers on both sides; a first electrochromic multilayer stack arranged on a first surface of the central transparent conductor ion blocking layer; and a second electrochromic multilayer stack arranged on a second surface of the central transparent conductor ion blocking layer, wherein the second electrochromic multilayer stack comprises: a second transparent conductor layer ; a fourth electrochromic layer arranged on the surface of the second transparent conductor layer; a second ion conductor layer arranged on the surface of the fourth electrochromic layer; and a third electrochromic layer arranged at the surface of the second ion conducting layer; wherein the third electrochromic layer is adjacent to the second surface of the central transparent conductor ion blocking layer, wherein the second transparent conductor layer has resistance to current flow substantially parallel to a major surface of the second transparent conductor layer that varies as a function of position within the second transparent conductor layer, wherein the flexible transparent film is made from plastic, and wherein the central transparent conductor ion blocking layer comprises ion conductivities between 10 -4 and 10 -20 S/cm, and electrical resistivity less than 100 Ohm-cm. a central transparent conductor ion blocking layer that contains a flexible transparent film coated with central transparent conductor layers on both sides; a first electrochromic multilayer stack arranged on a first surface of the central transparent conductor ion blocking layer; and a second electrochromic multilayer stack arranged on a second surface of the central transparent conductor ion blocking layer, wherein the second electrochromic multilayer stack comprises: a second transparent conductor layer ; a fourth electrochromic layer arranged on the surface of the second transparent conductor layer; a second ion conductor layer arranged on the surface of the fourth electrochromic layer; and a third electrochromic layer arranged at the surface of the second ion conducting layer; wherein the third electrochromic layer is adjacent to the second surface of the central transparent conductor ion blocking layer, wherein the second transparent conductor layer has resistance to current flow substantially parallel to a major surface of the second transparent conductor layer that varies as a function of position within the second transparent conductor layer, wherein the flexible transparent film is made from plastic, and wherein the central transparent conductor ion blocking layer comprises ion conductivities between 10 -4 and 10 -20 S/cm, and electrical resistivity less than 100 Ohm-cm. a second transparent conductor layer ; a fourth electrochromic layer arranged on the surface of the second transparent conductor layer; a second ion conductor layer arranged on the surface of the fourth electrochromic layer; and a third electrochromic layer arranged at the surface of the second ion conducting layer; wherein the third electrochromic layer is adjacent to the second surface of the central transparent conductor ion blocking layer, wherein the second transparent conductor layer has resistance to current flow substantially parallel to a major surface of the second transparent conductor layer that varies as a function of position within the second transparent conductor layer, wherein the flexible transparent film is made from plastic, and wherein the central transparent conductor ion blocking layer comprises ion conductivities between 10 -4 and 10 -20 S/cm, and electrical resistivity less than 100 Ohm-cm. <EOS>