A Bis(arenesulfonyl) Peroxide, an Ambient-Stable Oxidant, Is a Strong p‑Dopant for Organic Semiconductors

Strong p-dopants are required to dope high-ionization energy organic semiconductors for a variety of potential applications, but strong, simple one-electron oxidants are typically sensitive to reduction by atmospheric moisture and thus challenging to store or handle. Here we show that bis-(3,5-bis-(trifluoromethyl)-benzenesulfonyl) peroxidea dimer formed by two highly oxidizing radicalscan function as a water-stable yet powerful oxidant, cleanly reacting with some organic semiconductors to form two radical cations and two 3,5-bis-(trifluoromethyl)-benzenesulfonate anions, although in other cases sulfonylation reactions can also occur. Notably, this peroxide is capable of p-doping the high-ionization energy polymer poly-[(9,9-dioctylfluorene-2,7-diyl)-alt-(benzo-[2,1,3]-thiadiazol-4,7-diyl)] (F8BT) to afford electrical conductivities of up to 0.03 S cm^-1, while its use with electron-rich poly-(3,4-dialkoxythiophene-2,5-diyl) derivatives can afford values up to 100 S cm^-1. Quantum-chemical calculations reveal the peroxide oxidant behaves in a fashion mirroring that of relatively oxygen-stable, but highly reducing, n-dopants that have been developed based on dimers of organic radicals or organometallic sandwich compounds.