Conjugated polymers and organic materials are highly interesting for future optoelectronic applications including organic solar cells, organic/inorganic hybrid solar cells, organic transistors, organic photodiodes, organic thermoelectrics, organic light-emitting diodes, and quantum dot light-emitting diodes. We design and synthesize new polymer/organic semiconducting materials to obtain desirable optical and electronic properties. More specifically, molecular energy level, bandgap, carrier mobility, crystallinity, and film morphology are controlled by developing a new conjugated molecular backbone and introducing functional groups. Furthermore, device engineering is being conducted to improve electrical performance and stability.