As the practical demand for flexible/or stretchable power-conversion devices 
increases, the development of high-performance alternatives to brittle inorganic 
thermoelectric (TE) materials is essential. Organic polymers, nano-carbons, and their 
hybrid materials have been investigated as possible alternatives for flexible/or 
stretchable TE materials due to their well-known advantages including flexibility, light￾weight, low cost, easy processability, and scalability. Among them, nano-carbon 
materials and their composites have great potential for use in flexible/or stretchable TE 
materials because of their high electrical conductivities and controllable Seebeck 
coefficients (or thermopower). Here, we show the rationally designed flexible/or 
stretchable TE inks based on nano-carbons with excellent TE performance which is due 
to controlled carrier mobility. We believe that the strategy proposed here to improve the 
performance of flexible/or stretchable thermoelectric materials by controlling the carrier 
mobility and free volume shows a great potential for the preparation of flexible/or 
stretchable power conversion devices.