A thermally activated and highly miscible dopant for n-type organic thermoelectrics

Abstract

N-doping plays an irreplaceable role in controlling the electron concentration of organic semiconductors thus to improve performance of organic semiconductor devices. However, compared with many mature p-doping methods, n-doping of organic semiconductor is still of challenges. In particular, dopant stability/processability, counterion-semiconductor immiscibility and doping induced microstructure non-uniformity have restricted the application of n-doping in high-performance devices. Here, we report a computer-assisted screening approach to rationally design of a triaminomethane-type dopant, which exhibit extremely high stability and strong hydride donating property due to its thermally activated doping mechanism. This triaminomethane derivative shows excellent counterion-semiconductor miscibility (counter cations stay with the polymer side chains), high doping efficiency and uniformity. By using triaminomethane, we realize a record n-type conductivity of up to 21 S cm⁻¹ and power factors as high as 51 μW m⁻¹ K⁻² even in films with thicknesses over 10 μm, and we demonstrate the first reported all-polymer thermoelectric generator.

Realizing efficient n-doping in organic thermoelectrics remains a challenge due to dopant-semiconductor immiscibility, poor dopant stability and low doping efficiency. Here, the authors use computer-assisted screening to develop n-dopants for thermoelectric polymers that show record power factors.