Solution-processed flexible n-type S-doped Ag2Se thermoelectric generators for near-ambient-temperature energy harvest†

Among the different technologies to harvest renewable energy, thermoelectric (TE) generators (TEGs) represent a highly promising route capable of converting heat to electricity based on the Seebeck effect. Here, a new room temperature (RT) one-pot solution synthesis approach was proposed, together with a sulfur-doping strategy, to optimize the flexibility and the power factor of n-type S-doped Ag2Se TE thin films deposited by solution-processes, requiring only mild post-deposition annealing at 150 °C. Optimized S-doped flexible Ag2Se thin films exhibited a maximum power factor of ∼2058 μW/m/K2 at RT, allowing for the fabrication of flexible TEGs with a maximum power output (Pmax) of 3.98 μW under a near-RT ΔT of 31 K, equivalent to a power density of 11.06 W/m2. Multidomain applications were further demonstrated by these heavy-metal–free, flexible TEGs to harvest near-RT waste heat from laptop computers, non-concentrated sun light, and human body together with the realization of a self-powered motion detector. The current findings open promising paths for innovations on low-cost wearable smart electronics and energy harvesting.