The past decade has witnessed significant developments in stretchable electronics. Developing effective, low fabrication threshold and simple solution processing approaches will advance the development of stretchable electronics. Current solution processing approaches in the fabrication of stretchable electronics are mainly focused on spin coating and spray coating methods, which are simple but require complicated preliminary mask preparation. On the other hand, one modified three-dimensional (3D) printing-based solution processing method is a suitable candidate to fabricate stretchable electronics in a simple, flexible, and cost-effective way. Bar coating method is also a promising replacement for spin or spray coating to improve the alignment of nanostructures and modify charge carrier transport in naphthalene diimide (NDI)-based semiconducting polymer. However, research toward this modified 3D printing technique in stretchable electronics and bar coating-based solution processing approach of NDI-based semiconducting polymers is rare and limited. Therefore, we propose that 3D printing-based solution processing approach could serve as a novel and effective way to reduce the fabrication threshold of stretchable electronics and bar coating method has the potential to improve nanostructure alignment and is promising in modifying charge carrier transport of NDI-based semiconducting polymer films. This thesis focuses on investigations of fundamentally new, low fabrication threshold and effective solution processing approaches to fabricate stretchable electronics and improve transistor performance.