An image sensor device includes a semiconductor substrate, including an array of pixel circuits, which define respective pixels of the device. A photosensitive layer is formed over the semiconductor substrate and configured to transfer charge to the pixel circuits in response to light incident on the photosensitive layer. An upper layer is formed over the photosensitive layer and is at least partially transparent to the light. Opaque partitions extend vertically through the upper layer in a checkerboard pattern aligned with the pixels in the array.