Abstract
Printable electronics offer outstanding potential for novel electronic devices that can be lightweight, flexible, transparent, large area and low cost. These next generation electronics will aid the realization of concepts such as smart cities, structural health monitoring of advanced structures, body area networks, remote medical healthcare and the internet of things. Solution processed nanomaterials hold most of the promise as viable building blocks for these future applications. A robust and reproducible approach has been developed, for high definition one-step patterning of conductive electrodes, using inkjet printing (part A, chapter 4). Controlled electrode spacing and single droplet deposition was achieved by utilising the droplet kinematic stages and overcoming the built in limitations of our experimental setup. Single and multiple silicon nanowire (NW) field effect transistors were realised in a variety of electrode configurations, demonstrating the capabilities of our technique. The controlled realisation of single NW devices enabled the characterisation of semiconducting nanostructures by correlating their electrical response with defects introduced during growth. In chapter 7 (part B) a low-cost, scalable printing process to fabricate high-quality organic semicon-ducting single crystals (OSSCs) on virtually any substrate using various types of conjugated molecules is demonstrated. By combining the advantages of antisolvent crystallization and solution shearing with spray-printing, one-step single crystal growth of various small semiconducting molecules was realised. In addition, crystal size, shape, and orientation were controlled by the sheer force generated by the im-pact of the droplets from the spray onto the antisolvent’s surface, eliminating the need for pre-deposition patterning. For enabling large scale manufacturing of printable single crystal electronics, advances towards non-destructive characterisation techniques are required. In chapter 5 (part A), the capabilities of advanced scanning probe microscopy techniques as a non-destructive alternative for evaluating the growth and device integration defects in NW based devices, was explored. Conductive Atomic Force Microscopy (c-AFM) was used for imaging critical electrical characteristics with high spatial resolution. In chapter 8 (part B), the potentials of polarised Raman spectroscopy (p-Raman) as a non-destructive approach, for characterising the anisotropy in our OSSCs were explored. By using the aforementioned crystals as reference samples, the potential of the technique is demonstrated.