Mapping Structure-Property Relationships of Organic Color Centers

Organic color centers are an emergent class of quantum emitters that hold vast potential for applications in bioimaging, chemical sensing, and quantum information processing. Here, we show that these synthetic color centers follow interesting structure-property relationships through comparative spectral studies of 14 purified single-walled carbon nanotube chiralities and 30 different functional groups that vary in electron-withdrawing capability and bonding configurations. The defect emission is tunable by as much as 400 meV in the near-infrared as a function of host structure and the chemical nature of the color centers. However, the emission energy is nearly free from chiral angle and family patterns of the nanotube host (although this strongly depends on the nanotube diameter), suggesting that a trapped exciton at the organic color centers to some degree electronically decouples from the one-dimensional semiconductor host. Our findings provide important insights for designing and controlling this new family of synthetic color centers. Color centers, such as nitrogen vacancies in diamond, possess intriguing optical properties that have been intensively studied for imaging, sensing, lasing, and quantum information. However, most color centers occur as native defects, making tailored synthesis difficult. By covalently bonding functional groups to carbon nanotube semiconductors, we can synthetically create a whole new class of color centers that are organic and can be chemically tailored in highly predictable manners. These synthetic quantum emitters allow systematic tuning of the emission color in the near-infrared, a spectral regime that is important to biochemical imaging and quantum communications but had been largely unexplored. Unlike nitrogen vacancy centers in diamond, which is an electrical insulator, organic color centers are synthetically created in a semiconductor and electronically coupled to the host, opening the possibility for electrical addressing and chemical tailoring with molecular precision. Organic color centers are an emergent class of quantum emitters that hold vast potential for photonic, sensing, and optoelectronic applications. Covalently bonding functional groups to semiconducting single-walled carbon nanotubes creates molecularly tunable color centers where mobile excitons can be trapped and fluoresce brightly. Comparative studies of a series of 14 high-purity nanotube hosts and 30 organic color centers reveal new insights on the structure-property relationships that may be used to guide the synthesis of these centers featuring tailored light-emitting properties.