Adv. Mater. http://doi.org/f2xrf2 (2014)

Photodetectors based on organic materials are appealing alternatives to silicon devices because of their low cost, flexibility and sensitivity. In an efficient organic two-dimensional array working as an image detector, each pixel of the array is composed of a light-sensing element, a memory unit that stores the detected information and a selector that minimizes crosstalk — interference from adjacent pixels on the electric signal read from a specific unit. Sebastian Nau and colleagues now show that compact photosensor–storage–selector systems integrated in highly dense flexible arrays are obtained by vertically connecting in series an organic photodiode and an organic resistive switch. When exposed to light, the photodiode decreases its resistivity and the voltage applied to the series circuit drops across the resistive switch changing its status from high- to low-resistance. This status is preserved until a signal is applied to reset the switch. The nonlinear behaviour of the photodiode is used to minimize crosstalk during read-out.