An elastomer-semiconductor-elastomer stack structure can allow an intrinsically brittle n-type organic semiconductor to be stretched by 50% and used to make fully stretchable complementary electronics. Elastic integrated electronics are of potential use in a range of emerging applications, particularly those that require devices that can form an interface with soft biological tissue. The development of such devices has typically focused on the creation of stretchy p-type semiconductors, and the lack of suitable stretchy n-type semiconductors limits the potential of stretchable integrated systems. Here we show that a brittle n-type organic semiconductor can be made mechanically stretchable by integrating into a stack with an elastomer-semiconductor-elastomer architecture. The structure suppresses the formation and propagation of microcracks and can be stretched by up to 50% with negligible loss of performance. It also improves the long-term stability of the semiconductor in an ambient environment. We use the n-type elastomer-semiconductor-elastomer stack, together with other stretchy electronic materials, to build elastic transistors, digital logic gates, complementary electronics, p-n photodetectors and an active matrix multiplexed deformable imager.