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Like molecules of DNA, carbon nanotubes (CNTs) can display a variety of structures, but all conduct electrons and feature unique optical properties. In this perspective article, we highlight several recent works that bridge these two seemingly distant worlds. We illustrate the largely untapped potential of CNTs for biological research by exploring several developing biomedical applications utilizing nanotube semiconductors, including field effect transistor biosensors that couple high sensitivity with selectivity, and fluorophores for deep-tissue imaging whose excitation and emission wavelengths can be tuned throughout the near-IR II window simply by using defect chemistry. 

In this paper we report a unique electrical response of ethanol-adsorbed ZnO films subjected to a constant potential difference. Current measurements were obtained in both dark and illuminated conditions. A significant delay in achieving saturation current was observed indicating a nonlinear and time varying effective resistance; a time-dependent equation describing this behavior was developed, allowing the calculation of a time constant for the transition regime. To determine the role of the surface properties in this behavior, microwave plasma was used to etch the ZnO film by varying degrees, resulting in an enhancement of the resistance switching for extended etching times. 

Dye sensitized solar cells are a type of thin film solar cell used to convert sunlight into electrical energy. These devices use a different mechanism than conventional solar cells and can be made from materials which are biocompatible and biodegradable. The simplicity of design and small environmental impact of these devices make them a likely candidate for replacing conventional PV devices. Since these solar cells are thin film cells, they can be made to be transparent and can be printed on flexible substrate, allowing their incorporation into many household objects such as windows, backpacks, walls, and other objects which would otherwise not be used for energy generation. A wide variety of fabrication techniques and device designs exist for DSSCs, each having its benefits and deficiencies; it is the purpose of this paper to evaluate some of these design variations, including different semiconductor and dye types and scaffolds, as well as semiconductor surface treatment using microwave plasma. 

Abstract For thousands of years, carbon ink has been used as a black color pigment for writing and painting purposes. However, recent discoveries of nanocarbon materials, including fullerenes, carbon nanotubes, graphene, and their various derivative forms, together with the advances in large‐scale synthesis, are enabling a whole new generation of carbon inks that can serve as an intrinsically programmable materials platform for developing advanced functionalities far beyond color. The marriage between these multifunctional nanocarbon inks with modern printing technologies is facilitating and even transforming many applications, including flexible electronics, wearable and implantable sensors, actuators, and autonomous robotics. This review examines recent progress in the reborn field of carbon inks, highlighting their programmability and multifunctionality for applications in flexible electronics and stimuli‐responsive devices. Current challenges and opportunities will also be discussed from a materials science perspective towards the advancement of carbon ink for new applications beyond color. 

Abstract Single‐walled carbon nanotubes (SWCNTs) are a class of 1D nanomaterials that exhibit extraordinary electrical and optical properties. However, many of their fundamental studies and practical applications are stymied by sample polydispersity. SWCNTs are synthesized in bulk with broad structural (chirality) and geometrical (length and diameter) distributions; problematically, all known post‐synthetic sorting methods rely on ultrasonication, which cuts SWCNTs into short segments (typically <1 µm). It is demonstrated that ultralong (>10 µm) SWCNTs can be efficiently separated from shorter ones through a solution‐phase “self‐sorting”. It is shown that thin‐film transistors fabricated from long semiconducting SWCNTs exhibit a carrier mobility as high as ≈90 cm²V⁻¹s⁻¹, which is ≈10 times higher than those which use shorter counterparts and well exceeds other known materials such as organic semiconducting polymers (<1 cm²V⁻¹s⁻¹), amorphous silicon (≈1 cm²V⁻¹s⁻¹), and nanocrystalline silicon (≈50 cm²V⁻¹s⁻¹). Mechanistic studies suggest that this self‐sorting is driven by the length‐dependent solution phase behavior of rigid rods. This length sorting technique shows a path to attain long‐sought ultralong, electronically pure carbon nanotube materials through scalable solution processing.