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The survivability of living organisms relies critically on their ability to self-heal from damage in unpredictable situations and environmental variability. Such abilities are most important in external facing organs such as the mammalian skin. However, the properties of bulk elemental materials are typically unable to perform self-repair. Consequently, most conventional smart electronic devices today are not designed to repair themselves when damaged. Thus, inspired by the remarkable capability of self-healing in natural systems, smart self-healing materials are being intensively researched to mimic natural systems to have the ability to partially or completely self-repair damages inflicted on them. This exciting area of research could potentially power a sustainable and smart future.

Organic single-crystalline p-n junctions are grown from mixed solutions. First, C60 crystals (n-type) form and, subsequently, C8-BTBT crystals (p-type) nucleate heterogeneously on the C60 crystals. Both crystals continue to grow simultaneously into single-crystalline p-n junctions that exhibit ambipolar charge transport characteristics. This work provides a platform to study organic single-crystalline p-n junctions.

Organic single-crystalline heterojunctions are composed of different single crystals interfaced together. The intrinsic highly ordered heterostructure in these multicomponent solids holds the capacity for multifunctions, as well as superior charge-transporting properties, promising high-performance electronic applications such as ambipolar transistors and solar cells. However, this kind of heterojunction is not easily available and the preparation methods need to be developed. Recent advances in the efficient strategies that have emerged in yielding high-quality single-crystalline heterojunctions are highlighted here. The advantages and limitations of each strategy are also discussed. The obtained single-crystalline heterojunctions have started to exhibit rich physical properties, including metallic conduction, photovoltaic effects, and so on. Further structural optimization of the heterojunctions to accommodate the electronic device configuration is necessary to significantly advance this research direction.

TIPS-pentacene, a standard p-channel material, exhibits electron transport as it crystallizes from non-polar solvents.