SBIR Phase I: Innovations in Nanowire Manufacturing: Large Scale Synthesis of Inorganic Semiconducting Nanowires and Application to Printed Electronics

This Small Business Innovation Research Phase I project aims to develop large-scale manufacturing methods for inorganic semiconductor nanowires, specifically CdSe nanowires. An automated pilot reactor will be designed and built that will allow a reduction in materials cost and an improvement in the robustness of the synthesis, thus allowing a scale-up of nanowire production to multi-gram scale. The resulting nanowires will be incorporated into functional inks for printed/flexible electronics. A prototype printed photosensor will be produced as a demonstration. The demonstration device will validate that inorganic semiconducting nanowires can be incorporated into flexible/printed electronics using standard plastic substrates and commercial printing methods. The production of robust nanoinks will allow for easy incorporation into current commercial printed electronics manufacturing streams. While characterization of the materials and devices will involve a variety of techniques (including electron microscopy), the project will also focus on the validation of materials via simple optical metrology techniques (such as ultraviolet-visible spectroscopy) that could be incorporated in-line for large-scale manufacturing of nanomaterials, nanoinks, and printed substrates. The broader impact/commercial potential of this project will be to provide additional technologies for printed and flexible electronics. Flexible electronics technology is expected to be increasingly applied in a variety of applications including energy (photovoltaics, batteries, and lighting), consumer devices (displays, sensors, actuators), healthcare (sensors), communication (RFID), and defense (sensors, photovoltaics, displays). The area of flexible electronics is a rapidly growing market, with experts predicting a size of $250 billion by 2025. Appropriate technologies must be developed to replicate current solid state devices; these include printable semiconductors, insulators, conductors, and metals. Inorganic semiconducting nanowires are extremely appealing for printing; their morphology suggests that devices made with these materials would be flexible and transparent. CdSe nanowires have strong anisotropic absorption of light, suggesting their utility for thin-form photo- and polarization sensors. Such sensors are expected to be deployed in "smart" building sensor nets. The technology developed in this project will enable the creation of a variety of additional devices on a variety of substrates, including flexible films, such as plastics and metal foils, in addition to conventional rigid substrates such as glass or semiconductor wafers.