Conjugated polymers and organic materials are highly interesting for future optoelectronic applications including organic solar cells, organic transistors, organic thermoelectrics, organic photodiodes, quantum dot light emitting diodes, organic light emitting diodes, and molecular electronics. 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 new conjugated molecular backbone and introducing functional groups. Additionally, device engineering is being conducted to improve electrical performance.