An organic image sensor, comprising: an organic photoelectric conversion layer including a first material and a second material, the first material configured to absorb a first wavelength spectrum of light, the second material configured to absorb a second wavelength spectrum of light, and a common electrode on one side of the organic photoelectric conversion layer and a plurality of pixel electrodes on an opposite side of the organic photoelectric conversion layer, wherein the organic photoelectric conversion layer includes a lower layer and an upper layer stacked upon the lower layer, a material composition of the lower layer being a first mixture of the first and second materials, a material composition of the upper layer being a second mixture of the first and second materials, wherein the plurality of pixel electrodes define separate, first (OPD#1) and second (OPD#N) organic photoelectric conversion devices in the organic image sensor, such that the first organic photoelectric conversion device includes a first pixel electrode of the plurality of pixel electrodes, a first portion of the organic photoelectric conversion layer and a first portion of the common electrode, and the second organic photoelectric conversion device includes a separate, second pixel electrode of the plurality of pixel electrodes, a separate, second portion of the organic photoelectric conversion layer and a separate, second portion of the common electrode, wherein a ratio of the first material to the second material in the first mixture is greater than 1/1, and a ratio of the first material to the second material in the second mixture is less than 1/1, characterized in that the organic image sensor is configured to apply a first voltage in the first organic photoelectric conversion device and configured to concurrently apply a second voltage in the second organic photoelectric conversion device, a magnitude of the second voltage being greater than a magnitude of the first voltage. an organic photoelectric conversion layer including a first material and a second material, the first material configured to absorb a first wavelength spectrum of light, the second material configured to absorb a second wavelength spectrum of light, and a common electrode on one side of the organic photoelectric conversion layer and a plurality of pixel electrodes on an opposite side of the organic photoelectric conversion layer, wherein the organic photoelectric conversion layer includes a lower layer and an upper layer stacked upon the lower layer, a material composition of the lower layer being a first mixture of the first and second materials, a material composition of the upper layer being a second mixture of the first and second materials, wherein the plurality of pixel electrodes define separate, first (OPD#1) and second (OPD#N) organic photoelectric conversion devices in the organic image sensor, such that the first organic photoelectric conversion device includes a first pixel electrode of the plurality of pixel electrodes, a first portion of the organic photoelectric conversion layer and a first portion of the common electrode, and the second organic photoelectric conversion device includes a separate, second pixel electrode of the plurality of pixel electrodes, a separate, second portion of the organic photoelectric conversion layer and a separate, second portion of the common electrode, wherein a ratio of the first material to the second material in the first mixture is greater than 1/1, and a ratio of the first material to the second material in the second mixture is less than 1/1, characterized in that the organic image sensor is configured to apply a first voltage in the first organic photoelectric conversion device and configured to concurrently apply a second voltage in the second organic photoelectric conversion device, a magnitude of the second voltage being greater than a magnitude of the first voltage.